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2023-02-08perf lock contention: Add -o/--lock-owner optionNamhyung Kim
When there're many lock contentions in the system, people sometimes want to know who caused the contention, IOW who's the owner of the locks. The -o/--lock-owner option tries to follow the lock owners for the contended mutexes and rwsems from BPF, and then attributes the contention time to the owner instead of the waiter. It's a best effort approach to get the owner info at the time of the contention and doesn't guarantee to have the precise tracking of owners if it's changing over time. Currently it only handles mutex and rwsem that have owner field in their struct and it basically points to a task_struct that owns the lock at the moment. Technically its type is atomic_long_t and it comes with some LSB bits used for other meanings. So it needs to clear them when casting it to a pointer to task_struct. Also the atomic_long_t is a typedef of the atomic 32 or 64 bit types depending on arch which is a wrapper struct for the counter value. I'm not aware of proper ways to access those kernel atomic types from BPF so I just read the internal counter value directly. Please let me know if there's a better way. When -o/--lock-owner option is used, it goes to the task aggregation mode like -t/--threads option does. However it cannot get the owner for other lock types like spinlock and sometimes even for mutex. $ sudo ./perf lock con -abo -- ./perf bench sched pipe # Running 'sched/pipe' benchmark: # Executed 1000000 pipe operations between two processes Total time: 4.766 [sec] 4.766540 usecs/op 209795 ops/sec contended total wait max wait avg wait pid owner 403 565.32 us 26.81 us 1.40 us -1 Unknown 4 27.99 us 8.57 us 7.00 us 1583145 sched-pipe 1 8.25 us 8.25 us 8.25 us 1583144 sched-pipe 1 2.03 us 2.03 us 2.03 us 5068 chrome As you can see, the owner is unknown for the most cases. But if we filter only for the mutex locks, it'd more likely get the onwers. $ sudo ./perf lock con -abo -Y mutex -- ./perf bench sched pipe # Running 'sched/pipe' benchmark: # Executed 1000000 pipe operations between two processes Total time: 4.910 [sec] 4.910435 usecs/op 203647 ops/sec contended total wait max wait avg wait pid owner 2 15.50 us 8.29 us 7.75 us 1582852 sched-pipe 7 7.20 us 2.47 us 1.03 us -1 Unknown 1 6.74 us 6.74 us 6.74 us 1582851 sched-pipe Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Hao Luo <haoluo@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230207002403.63590-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-02-08perf lock contention: Fix to save callstack for the default modifiedNamhyung Kim
The previous change missed to set the con->save_callstack for the LOCK_AGGR_CALLER mode resulting in no caller information. Fixes: ebab291641bed48f ("perf lock contention: Support filters for different aggregation") Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Hao Luo <haoluo@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230207002403.63590-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-02-03perf lock contention: Support filters for different aggregationNamhyung Kim
It'd be useful to filter other than the current aggregation mode. For example, users may want to see callstacks for specific locks only. Or they may want tasks from a certain callstack. The tracepoints already collected the information but it needs to check the condition again when processing the event. And it needs to change BPF to allow the key combinations. The lock contentions on 'rcu_state' spinlock can be monitored: $ sudo perf lock con -abv -L rcu_state sleep 1 ... contended total wait max wait avg wait type caller 4 151.39 us 62.57 us 37.85 us spinlock rcu_core+0xcb 0xffffffff81fd1666 _raw_spin_lock_irqsave+0x46 0xffffffff8172d76b rcu_core+0xcb 0xffffffff822000eb __softirqentry_text_start+0xeb 0xffffffff816a0ba9 __irq_exit_rcu+0xc9 0xffffffff81fc0112 sysvec_apic_timer_interrupt+0xa2 0xffffffff82000e46 asm_sysvec_apic_timer_interrupt+0x16 0xffffffff81d49f78 cpuidle_enter_state+0xd8 0xffffffff81d4a259 cpuidle_enter+0x29 1 30.21 us 30.21 us 30.21 us spinlock rcu_core+0xcb 0xffffffff81fd1666 _raw_spin_lock_irqsave+0x46 0xffffffff8172d76b rcu_core+0xcb 0xffffffff822000eb __softirqentry_text_start+0xeb 0xffffffff816a0ba9 __irq_exit_rcu+0xc9 0xffffffff81fc00c4 sysvec_apic_timer_interrupt+0x54 0xffffffff82000e46 asm_sysvec_apic_timer_interrupt+0x16 1 28.84 us 28.84 us 28.84 us spinlock rcu_accelerate_cbs_unlocked+0x40 0xffffffff81fd1c60 _raw_spin_lock+0x30 0xffffffff81728cf0 rcu_accelerate_cbs_unlocked+0x40 0xffffffff8172da82 rcu_core+0x3e2 0xffffffff822000eb __softirqentry_text_start+0xeb 0xffffffff816a0ba9 __irq_exit_rcu+0xc9 0xffffffff81fc0112 sysvec_apic_timer_interrupt+0xa2 0xffffffff82000e46 asm_sysvec_apic_timer_interrupt+0x16 0xffffffff81d49f78 cpuidle_enter_state+0xd8 ... To see tasks calling 'rcu_core' function: $ sudo perf lock con -abt -S rcu_core sleep 1 contended total wait max wait avg wait pid comm 19 23.46 us 2.21 us 1.23 us 0 swapper 2 18.37 us 17.01 us 9.19 us 2061859 ThreadPoolForeg 3 5.76 us 1.97 us 1.92 us 3909 pipewire-pulse 1 2.26 us 2.26 us 2.26 us 1809271 MediaSu~isor #2 1 1.97 us 1.97 us 1.97 us 1514882 Chrome_ChildIOT 1 987 ns 987 ns 987 ns 3740 pipewire-pulse Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Hao Luo <haoluo@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230203021324.143540-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-02-03perf lock contention: Use lock_stat_find{,new}Namhyung Kim
This is a preparation work to support complex keys of BPF maps. Now it has single value key according to the aggregation mode like stack_id or pid. But we want to use a combination of those keys. Then lock_contention_read() should still aggregate the result based on the key that was requested by user. The other key info will be used for filtering. So instead of creating a lock_stat entry always, Check if it's already there using lock_stat_find() first. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Hao Luo <haoluo@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230203021324.143540-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-02-02perf lock contention: Add -S/--callstack-filter optionNamhyung Kim
The -S/--callstack-filter is to limit display entries having the given string in the callstack (not only in the caller in the output). The following example shows lock contention results if the callstack has 'net' substring somewhere. Note that the caller '__dev_queue_xmit' does not match to it, but it has 'inet6_csk_xmit' in the callstack. This applies even if you don't use -v option to show the full callstack. $ sudo ./perf lock con -abv -S net sleep 1 ... contended total wait max wait avg wait type caller 5 70.20 us 16.13 us 14.04 us spinlock __dev_queue_xmit+0xb6d 0xffffffffa5dd1c60 _raw_spin_lock+0x30 0xffffffffa5b8f6ed __dev_queue_xmit+0xb6d 0xffffffffa5cd8267 ip6_finish_output2+0x2c7 0xffffffffa5cdac14 ip6_finish_output+0x1d4 0xffffffffa5cdb477 ip6_xmit+0x457 0xffffffffa5d1fd17 inet6_csk_xmit+0xd7 0xffffffffa5c5f4aa __tcp_transmit_skb+0x54a 0xffffffffa5c6467d tcp_keepalive_timer+0x2fd Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230126000936.3017683-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-01-03perf lock contention: Fix core dump related to not finding the ↵Thomas Richter
"__sched_text_end" symbol on s/390 The test case perf lock contention dumps core on s390. Run the following commands: # ./perf lock record -- ./perf bench sched messaging # Running 'sched/messaging' benchmark: # 20 sender and receiver processes per group # 10 groups == 400 processes run Total time: 2.799 [sec] [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.073 MB perf.data (100 samples) ] # # ./perf lock contention Segmentation fault (core dumped) # The function call stack is lengthy, here are the top 5 functions: # gdb ./perf core.24048 GNU gdb (GDB) Fedora Linux 12.1-6.fc37 Core was generated by `./perf lock contention'. Program terminated with signal SIGSEGV, Segmentation fault. #0 0x00000000011dd25c in machine__is_lock_function (machine=0x3029e28, addr=1789230) at util/machine.c:3356 3356 machine->sched.text_end = kmap->unmap_ip(kmap, sym->start); (gdb) where #0 0x00000000011dd25c in machine__is_lock_function (machine=0x3029e28, addr=1789230) at util/machine.c:3356 #1 0x000000000109f244 in callchain_id (evsel=0x30313e0, sample=0x3ffea4f77d0) at builtin-lock.c:957 #2 0x000000000109e094 in get_key_by_aggr_mode (key=0x3ffea4f7290, addr=27758136, evsel=0x30313e0, sample=0x3ffea4f77d0) at builtin-lock.c:586 #3 0x000000000109f4d0 in report_lock_contention_begin_event (evsel=0x30313e0, sample=0x3ffea4f77d0) at builtin-lock.c:1004 #4 0x00000000010a00ae in evsel__process_contention_begin (evsel=0x30313e0, sample=0x3ffea4f77d0) at builtin-lock.c:1254 #5 0x00000000010a0e14 in process_sample_event (tool=0x3ffea4f8480, event=0x3ff85601ef8, sample=0x3ffea4f77d0, evsel=0x30313e0, machine=0x3029e28) at builtin-lock.c:1464 ..... The issue is in function machine__is_lock_function() in file ./util/machine.c lines 3355: /* should not fail from here */ sym = machine__find_kernel_symbol_by_name(machine, "__sched_text_end", &kmap); machine->sched.text_end = kmap->unmap_ip(kmap, sym->start) On s390 the symbol __sched_text_end is *NOT* in the symbol list and the resulting pointer sym is set to NULL. The sym->start is then a NULL pointer access and generates the core dump. The reason why __sched_text_end is not in the symbol list on s390 is simple: When the symbol list is created at perf start up with function calls dso__load +--> dso__load_vmlinux_path +--> dso__load_vmlinux +--> dso__load_sym +--> dso__load_sym_internal (reads kernel symbols) +--> symbols__fixup_end +--> symbols__fixup_duplicate The issue is in function symbols__fixup_duplicate(). It deletes all symbols with have the same address. On s390: # nm -g ~/linux/vmlinux| fgrep c68390 0000000000c68390 T __cpuidle_text_start 0000000000c68390 T __sched_text_end # two symbols have identical addresses and __sched_text_end is considered duplicate (in ascending sort order) and removed from the symbol list. Therefore it is missing and an invalid pointer reference occurs. The code checks for symbol __sched_text_start and when it exists assumes symbol __sched_text_end is also in the symbol table. However this is not the case on s390. Same situation exists for symbol __lock_text_start: 0000000000c68770 T __cpuidle_text_end 0000000000c68770 T __lock_text_start This symbol is also removed from the symbol table but used in function machine__is_lock_function(). To fix this and keep duplicate symbols in the symbol table, set symbol_conf.allow_aliases to true. This prevents the removal of duplicate symbols in function symbols__fixup_duplicate(). Output After: # ./perf lock contention contended total wait max wait avg wait type caller 48 124.39 ms 123.99 ms 2.59 ms rwsem:W unlink_anon_vmas+0x24a 47 83.68 ms 83.26 ms 1.78 ms rwsem:W free_pgtables+0x132 5 41.22 us 10.55 us 8.24 us rwsem:W free_pgtables+0x140 4 40.12 us 20.55 us 10.03 us rwsem:W copy_process+0x1ac8 # Fixes: 0d2997f750d1de39 ("perf lock: Look up callchain for the contended locks") Signed-off-by: Thomas Richter <tmricht@linux.ibm.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Sumanth Korikkar <sumanthk@linux.ibm.com> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Link: https://lore.kernel.org/r/20221230102627.2410847-1-tmricht@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-21perf lock contention: Add -L/--lock-filter optionNamhyung Kim
The -L/--lock-filter option is to filter only given locks. The locks can be specified by address or name (if exists). $ sudo ./perf lock record -a sleep 1 $ sudo ./perf lock con -l contended total wait max wait avg wait address symbol 57 1.11 ms 42.83 us 19.54 us ffff9f4140059000 15 280.88 us 23.51 us 18.73 us ffffffff9d007a40 jiffies_lock 1 20.49 us 20.49 us 20.49 us ffffffff9d0d50c0 rcu_state 1 9.02 us 9.02 us 9.02 us ffff9f41759e9ba0 $ sudo ./perf lock con -L jiffies_lock,rcu_state contended total wait max wait avg wait type caller 15 280.88 us 23.51 us 18.73 us spinlock tick_sched_do_timer+0x93 1 20.49 us 20.49 us 20.49 us spinlock __softirqentry_text_start+0xeb $ sudo ./perf lock con -L ffff9f4140059000 contended total wait max wait avg wait type caller 38 779.40 us 42.83 us 20.51 us spinlock worker_thread+0x50 11 216.30 us 39.87 us 19.66 us spinlock queue_work_on+0x39 8 118.13 us 20.51 us 14.77 us spinlock kthread+0xe5 Committer testing: # uname -a Linux quaco 6.0.12-200.fc36.x86_64 #1 SMP PREEMPT_DYNAMIC Thu Dec 8 17:15:53 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux # perf lock record ^C[ perf record: Woken up 1 times to write data ] # perf lock con -L jiffies_lock,rcu_state contended total wait max wait avg wait type caller # perf lock con contended total wait max wait avg wait type caller 1 9.06 us 9.06 us 9.06 us spinlock call_timer_fn+0x24 # perf lock con -L call ignore unknown symbol: call contended total wait max wait avg wait type caller 1 9.06 us 9.06 us 9.06 us spinlock call_timer_fn+0x24 # Signed-off-by: Namhyung Kim <namhyung@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Blake Jones <blakejones@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20221219201732.460111-5-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-21perf lock contention: Support lock type filtering for BPFNamhyung Kim
Likewise, add type_filter BPF hash map and check it when user gave a lock type filter. $ sudo ./perf lock con -ab -Y rwlock -- ./perf bench sched messaging # Running 'sched/messaging' benchmark: # 20 sender and receiver processes per group # 10 groups == 400 processes run Total time: 0.203 [sec] contended total wait max wait avg wait type caller 15 156.19 us 19.45 us 10.41 us rwlock:W do_exit+0x36d 1 11.12 us 11.12 us 11.12 us rwlock:R do_wait+0x8b 1 5.09 us 5.09 us 5.09 us rwlock:W release_task+0x6e Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Blake Jones <blakejones@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20221219201732.460111-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-21perf lock contention: Add -Y/--type-filter optionNamhyung Kim
The -Y/--type-filter option is to filter the result for specific lock types only. It can accept comma-separated values. Note that it would accept type names like one in the output. spinlock, mutex, rwsem:R and so on. For RW-variant lock types, it converts the name to the both variants. In other words, "rwsem" is same as "rwsem:R,rwsem:W". Also note that "mutex" has two different encoding - one for sleeping wait, another for optimistic spinning. Add "mutex-spin" entry for the lock_type_table so that we can add it for "mutex" under the table. $ sudo ./perf lock record -a -- ./perf bench sched messaging $ sudo ./perf lock con -E 5 -Y spinlock contended total wait max wait avg wait type caller 802 1.26 ms 11.73 us 1.58 us spinlock __wake_up_common_lock+0x62 13 787.16 us 105.44 us 60.55 us spinlock remove_wait_queue+0x14 12 612.96 us 78.70 us 51.08 us spinlock prepare_to_wait+0x27 114 340.68 us 12.61 us 2.99 us spinlock try_to_wake_up+0x1f5 83 226.38 us 9.15 us 2.73 us spinlock folio_lruvec_lock_irqsave+0x5e Committer notes: Make get_type_flag() return UINT_MAX for error instad of -1UL, as that function returns 'unsigned int' and we store the value on a 'unsigned int' 'flags' variable which makes clang unhappy: 35 98.23 fedora:37 : FAIL clang version 15.0.6 (Fedora 15.0.6-1.fc37) builtin-lock.c:2012:14: error: result of comparison of constant 18446744073709551615 with expression of type 'unsigned int' is always true [-Werror,-Wtautological-constant-out-of-range-compare] if (flags != -1UL) { ~~~~~ ^ ~~~~ builtin-lock.c:2021:14: error: result of comparison of constant 18446744073709551615 with expression of type 'unsigned int' is always true [-Werror,-Wtautological-constant-out-of-range-compare] if (flags != -1UL) { ~~~~~ ^ ~~~~ builtin-lock.c:2037:14: error: result of comparison of constant 18446744073709551615 with expression of type 'unsigned int' is always true [-Werror,-Wtautological-constant-out-of-range-compare] if (flags != -1UL) { ~~~~~ ^ ~~~~ 3 errors generated. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Blake Jones <blakejones@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20221219201732.460111-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-20perf lock contention: Factor out lock_type_tableNamhyung Kim
Move it out of get_type_str() so that we can reuse the table for others later. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Blake Jones <blakejones@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20221219201732.460111-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-20perf tools: Fix usage of the verbose variableYang Jihong
The data type of the verbose variable is integer and can be negative, replace improperly used cases in a unified manner: 1. if (verbose) => if (verbose > 0) 2. if (!verbose) => if (verbose <= 0) 3. if (XX && verbose) => if (XX && verbose > 0) 4. if (XX && !verbose) => if (XX && verbose <= 0) Reviewed-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Yang Jihong <yangjihong1@huawei.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Carsten Haitzler <carsten.haitzler@arm.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Leo Yan <leo.yan@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Martin KaFai Lau <martin.lau@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Bangoria <ravi.bangoria@amd.com> Link: https://lore.kernel.org/r/20221220035702.188413-3-yangjihong1@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-14perf lock contention: Add -l/--lock-addr optionNamhyung Kim
The -l/--lock-addr option is to implement per-lock-instance contention stat using LOCK_AGGR_ADDR. It displays lock address and optionally symbol name if exists. $ sudo ./perf lock con -abl sleep 1 contended total wait max wait avg wait address symbol 1 36.28 us 36.28 us 36.28 us ffff92615d6448b8 9 10.91 us 1.84 us 1.21 us ffffffffbaed50c0 rcu_state 1 10.49 us 10.49 us 10.49 us ffff9262ac4f0c80 8 4.68 us 1.67 us 585 ns ffffffffbae07a40 jiffies_lock 3 3.03 us 1.45 us 1.01 us ffff9262277861e0 1 924 ns 924 ns 924 ns ffff926095ba9d20 1 436 ns 436 ns 436 ns ffff9260bfda4f60 Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Blake Jones <blakejones@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20221209190727.759804-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-14perf lock contention: Implement -t/--threads option for BPFNamhyung Kim
The BPF didn't show the per-thread stat properly. Use task's thread id (PID) as a key instead of stack_id and add a task_data map to save task comm names. $ sudo ./perf lock con -abt -E 5 sleep 1 contended total wait max wait avg wait pid comm 1 740.66 ms 740.66 ms 740.66 ms 1950 nv_queue 3 305.50 ms 298.19 ms 101.83 ms 1884 nvidia-modeset/ 1 25.14 us 25.14 us 25.14 us 2725038 EventManager_De 12 23.09 us 9.30 us 1.92 us 0 swapper 1 20.18 us 20.18 us 20.18 us 2725033 EventManager_De Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Blake Jones <blakejones@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <song@kernel.org> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20221209190727.759804-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-12-14machine: Adopt is_lock_function() from builtin-lock.cArnaldo Carvalho de Melo
It is used in bpf_lock_contention.c and builtin-lock.c will be made CONFIG_LIBTRACEEVENT=y conditional, so move it to machine.c, that is always available. This makes those 4 global variables for sched and lock text start and end to move to 'struct machine' too, as conceivably we can have that info for several machine instances, say some 'perf diff' like tool. Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: bpf@vger.kernel.org Link: http://lore.kernel.org/lkml/ Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-11-10perf lock: Allow concurrent record and reportNamhyung Kim
To support live monitoring of kernel lock contention without BPF, it should support something like below: # perf lock record -a -o- sleep 1 | perf lock contention -i- contended total wait max wait avg wait type caller 2 10.27 us 6.17 us 5.13 us spinlock load_balance+0xc03 1 5.29 us 5.29 us 5.29 us rwlock:W ep_scan_ready_list+0x54 1 4.12 us 4.12 us 4.12 us spinlock smpboot_thread_fn+0x116 1 3.28 us 3.28 us 3.28 us mutex pipe_read+0x50 To do that, it needs to handle HEAD_ATTR, HEADER_EVENT_UPDATE and HEADER_TRACING_DATA which are generated only for the pipe mode. And setting event handler also should be delayed until it gets the event information. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20221104051440.220989-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-31perf lock contention: Check --max-stack optionNamhyung Kim
The --max-stack option is used to allocate the BPF stack map and stack trace array in the userspace. Check the value properly before using. Practically it cannot be greater than the sysctl_perf_event_max_stack. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20221028180128.3311491-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-27perf tools: Make quiet mode consistent between toolsJames Clark
Use the global quiet variable everywhere so that all tools hide warnings in quiet mode and update the documentation to reflect this. 'perf probe' claimed that errors are not printed in quiet mode but I don't see this so remove it from the docs. Signed-off-by: James Clark <james.clark@arm.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20221018094137.783081-3-james.clark@arm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-04perf lock: Add -q/--quiet option to suppress header and debug messagesNamhyung Kim
Like in 'perf report', this option is to suppress header and debug messages. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20220924004221.841024-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-04perf lock: Add -E/--entries optionNamhyung Kim
Like in 'perf top', the -E option can limit number of entries to print. It can be useful when users want to see top N contended locks only. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Ian Rogers <irogers@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20220924004221.841024-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-04perf lock contention: Allow to change stack depth and skipNamhyung Kim
It needs stack traces to find callers of locks. To minimize the performance overhead it only collects up to 8 entries for each stack trace. And it skips first 3 entries as they came from BPF, tracepoint and lock functions which are not interested for most users. But it turned out that those numbers are different in some configuration. Using fixed number can result in non meaningful caller names. Let's make them adjustable with --stack-depth and --skip-stack options. On my setup, the default output is like below: # /perf lock con -ab -F contended,wait_total sleep 3 contended total wait type caller 28 4.55 ms rwlock:W __bpf_trace_contention_begin+0xb 33 1.67 ms rwlock:W __bpf_trace_contention_begin+0xb 12 580.28 us spinlock __bpf_trace_contention_begin+0xb 60 240.54 us rwsem:R __bpf_trace_contention_begin+0xb 27 64.45 us spinlock __bpf_trace_contention_begin+0xb If I change the stack skip to 5, the result will be like: # perf lock con -ab -F contended,wait_total --stack-skip 5 sleep 3 contended total wait type caller 32 715.45 us spinlock folio_lruvec_lock_irqsave+0x61 26 550.22 us spinlock folio_lruvec_lock_irqsave+0x61 15 486.93 us rwsem:R mmap_read_lock+0x13 12 139.66 us rwsem:W vm_mmap_pgoff+0x93 1 7.04 us spinlock tick_do_update_jiffies64+0x25 Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <songliubraving@fb.com> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20220912055314.744552-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-04perf lock contention: Show full callstack with -v optionNamhyung Kim
Currently it shows a caller function for each entry, but users need to see the full call stacks sometimes. Use -v/--verbose option to do that. # perf lock con -a -b -v sleep 3 Looking at the vmlinux_path (8 entries long) symsrc__init: cannot get elf header. Using /proc/kcore for kernel data Using /proc/kallsyms for symbols contended total wait max wait avg wait type caller 1 10.74 us 10.74 us 10.74 us spinlock __bpf_trace_contention_begin+0xb 0xffffffffc03b5c47 bpf_prog_bf07ae9e2cbd02c5_contention_begin+0x117 0xffffffffc03b5c47 bpf_prog_bf07ae9e2cbd02c5_contention_begin+0x117 0xffffffffbb8b8e75 bpf_trace_run2+0x35 0xffffffffbb7eab9b __bpf_trace_contention_begin+0xb 0xffffffffbb7ebe75 queued_spin_lock_slowpath+0x1f5 0xffffffffbc1c26ff _raw_spin_lock+0x1f 0xffffffffbb841015 tick_do_update_jiffies64+0x25 0xffffffffbb8409ee tick_irq_enter+0x9e 1 7.70 us 7.70 us 7.70 us spinlock __bpf_trace_contention_begin+0xb 0xffffffffc03b5c47 bpf_prog_bf07ae9e2cbd02c5_contention_begin+0x117 0xffffffffc03b5c47 bpf_prog_bf07ae9e2cbd02c5_contention_begin+0x117 0xffffffffbb8b8e75 bpf_trace_run2+0x35 0xffffffffbb7eab9b __bpf_trace_contention_begin+0xb 0xffffffffbb7ebe75 queued_spin_lock_slowpath+0x1f5 0xffffffffbc1c26ff _raw_spin_lock+0x1f 0xffffffffbb7bc27e raw_spin_rq_lock_nested+0xe 0xffffffffbb7cef9c load_balance+0x66c Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <songliubraving@fb.com> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20220912055314.744552-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-04perf lock contention: Factor out get_symbol_name_offset()Namhyung Kim
It's to convert addr to symbol+offset. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <songliubraving@fb.com> Cc: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20220912055314.744552-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-04perf lock: Add get_key_by_aggr_mode helperShang XiaoJing
Wrap repeated code in helper functions get_key_by_aggr_mode and get_key_by_aggr_mode_simple, which assign the value to key based on aggregation mode. Note that for the conditions not support LOCK_AGGR_CALLER, should call get_key_by_aggr_mode_simple directly. Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20220908021141.27134-3-shangxiaojing@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-10-04perf lock: Remove unused pthread.h includeIan Rogers
No pthread usage in builtin-lock.c. Signed-off-by: Ian Rogers <irogers@google.com> Reviewed-by: Adrian Hunter <adrian.hunter@intel.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Alexandre Truong <alexandre.truong@arm.com> Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Andres Freund <andres@anarazel.de> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: André Almeida <andrealmeid@igalia.com> Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com> Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Cc: Colin Ian King <colin.king@intel.com> Cc: Dario Petrillo <dario.pk1@gmail.com> Cc: Darren Hart <dvhart@infradead.org> Cc: Dave Marchevsky <davemarchevsky@fb.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Fangrui Song <maskray@google.com> Cc: Hewenliang <hewenliang4@huawei.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Clark <james.clark@arm.com> Cc: Jason Wang <wangborong@cdjrlc.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Kajol Jain <kjain@linux.ibm.com> Cc: Kim Phillips <kim.phillips@amd.com> Cc: Leo Yan <leo.yan@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Martin Liška <mliska@suse.cz> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Pavithra Gurushankar <gpavithrasha@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Quentin Monnet <quentin@isovalent.com> Cc: Ravi Bangoria <ravi.bangoria@amd.com> Cc: Remi Bernon <rbernon@codeweavers.com> Cc: Riccardo Mancini <rickyman7@gmail.com> Cc: Song Liu <songliubraving@fb.com> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Thomas Richter <tmricht@linux.ibm.com> Cc: Tom Rix <trix@redhat.com> Cc: Weiguo Li <liwg06@foxmail.com> Cc: Wenyu Liu <liuwenyu7@huawei.com> Cc: William Cohen <wcohen@redhat.com> Cc: Zechuan Chen <chenzechuan1@huawei.com> Cc: bpf@vger.kernel.org Cc: llvm@lists.linux.dev Cc: yaowenbin <yaowenbin1@huawei.com> Link: https://lore.kernel.org/r/20220826164242.43412-7-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-09-08perf lock: Remove redundant word 'contention' in help messageYang Jihong
Before: # perf lock -h Usage: perf lock [<options>] {record|report|script|info|contention|contention} -D, --dump-raw-trace dump raw trace in ASCII -f, --force don't complain, do it -i, --input <file> input file name -v, --verbose be more verbose (show symbol address, etc) --kallsyms <file> kallsyms pathname --vmlinux <file> vmlinux pathname After: # perf lock -h Usage: perf lock [<options>] {record|report|script|info|contention} -D, --dump-raw-trace dump raw trace in ASCII -f, --force don't complain, do it -i, --input <file> input file name -v, --verbose be more verbose (show symbol address, etc) --kallsyms <file> kallsyms pathname --vmlinux <file> vmlinux pathname Fixes: 528b9cab3b813a3b ("perf lock: Add 'contention' subcommand") Signed-off-by: Yang Jihong <yangjihong1@huawei.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20220908014854.151203-1-yangjihong1@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-08-02perf lock: Print the number of lost entries for BPFNamhyung Kim
Like the normal 'perf lock contention' output, it'd print the number of lost entries for BPF if exists or -v option is passed. Currently it uses BROKEN_CONTENDED stat for the lost count (due to full stack maps). $ sudo perf lock con -a -b --map-nr-entries 128 sleep 5 ... === output for debug=== bad: 43, total: 14903 bad rate: 0.29 % histogram of events caused bad sequence acquire: 0 acquired: 0 contended: 43 release: 0 Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Blake Jones <blakejones@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <songliubraving@fb.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220802191004.347740-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-08-02perf lock: Add --map-nr-entries optionNamhyung Kim
The --map-nr-entries option is to control number of max entries in the perf lock contention BPF maps. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Blake Jones <blakejones@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <songliubraving@fb.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220802191004.347740-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-08-02perf lock: Introduce struct lock_contentionNamhyung Kim
The lock_contention struct is to carry related fields together and to minimize the change when we add new config options. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Blake Jones <blakejones@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Song Liu <songliubraving@fb.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220802191004.347740-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-08-02perf parse-events: Break out tracepoint and printingIan Rogers
Move print_*_events functions out of parse-events.c into a new print-events.c. Move tracepoint code into tracepoint.c or trace-event-info.c (sole user). This reduces the dependencies of parse-events.c and makes it more amenable to being a library in the future. Remove some unnecessary definitions from parse-events.h. Fix a checkpatch.pl warning on using unsigned rather than unsigned int. Fix some line length warnings too. Signed-off-by: Ian Rogers <irogers@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: https://lore.kernel.org/r/20220729204217.250166-3-irogers@google.com [ Add include linux/stddef.h before perf_events.h for systems where __always_inline isn't pulled in before used, such as older Alpine Linux ] Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-08-01perf lock: Implement cpu and task filters for BPFNamhyung Kim
Add -a/--all-cpus and -C/--cpu options for cpu filtering. Also -p/--pid and --tid options are added for task filtering. The short -t option is taken for --threads already. Tracking the command line workload is possible as well. $ sudo perf lock contention -a -b sleep 1 Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Blake Jones <blakejones@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220729200756.666106-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-08-01perf lock: Use BPF for lock contention analysisNamhyung Kim
Add -b/--use-bpf option to use BPF to collect lock contention stats. For simplicity it now runs system-wide and requires C-c to stop. Upcoming changes will add the usual filtering. $ sudo perf lock con -b ^C contended total wait max wait avg wait type caller 42 192.67 us 13.64 us 4.59 us spinlock queue_work_on+0x20 23 85.54 us 10.28 us 3.72 us spinlock worker_thread+0x14a 6 13.92 us 6.51 us 2.32 us mutex kernfs_iop_permission+0x30 3 11.59 us 10.04 us 3.86 us mutex kernfs_dop_revalidate+0x3c 1 7.52 us 7.52 us 7.52 us spinlock kthread+0x115 1 7.24 us 7.24 us 7.24 us rwlock:W sys_epoll_wait+0x148 2 7.08 us 3.99 us 3.54 us spinlock delayed_work_timer_fn+0x1b 1 6.41 us 6.41 us 6.41 us spinlock idle_balance+0xa06 2 2.50 us 1.83 us 1.25 us mutex kernfs_iop_lookup+0x2f 1 1.71 us 1.71 us 1.71 us mutex kernfs_iop_getattr+0x2c Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Blake Jones <blakejones@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220729200756.666106-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-08-01perf lock: Pass machine pointer to is_lock_function()Namhyung Kim
This is a preparation for later change to expose the function externally so that it can be used without the implicit session data. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Blake Jones <blakejones@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220729200756.666106-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-07-25perf lock: Support -t option for 'contention' subcommandNamhyung Kim
Like perf lock report, it can report lock contention stat of each task. $ perf lock contention -t contended total wait max wait avg wait pid comm 5 945.20 us 902.08 us 189.04 us 316167 EventManager_De 33 98.17 us 6.78 us 2.97 us 766063 kworker/0:1-get 7 92.47 us 61.26 us 13.21 us 316170 EventManager_De 14 76.31 us 12.87 us 5.45 us 12949 timedcall 24 76.15 us 12.27 us 3.17 us 767992 sched-pipe 15 75.62 us 11.93 us 5.04 us 15127 switchto-defaul 24 71.84 us 5.59 us 2.99 us 629168 kworker/u513:2- 17 67.41 us 7.94 us 3.96 us 13504 coroner- 1 59.56 us 59.56 us 59.56 us 316165 EventManager_De 14 56.21 us 6.89 us 4.01 us 0 swapper Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220725183124.368304-6-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-07-25perf lock: Add -k and -F options to 'contention' subcommandNamhyung Kim
Like perf lock report, add -k/--key and -F/--field options to control output formatting and sorting. Note that it has slightly different default options as some fields are not available and to optimize the screen space. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220725183124.368304-5-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-07-25perf lock: Add 'contention' subcommandNamhyung Kim
The 'perf lock contention' processes the lock contention events and displays the result like perf lock report. Right now, there's not much difference between the two but the lock contention specific features will come soon. $ perf lock contention contended total wait max wait avg wait type caller 238 1.41 ms 29.20 us 5.94 us spinlock update_blocked_averages+0x4c 1 902.08 us 902.08 us 902.08 us rwsem:R do_user_addr_fault+0x1dd 81 330.30 us 17.24 us 4.08 us spinlock _nohz_idle_balance+0x172 2 89.54 us 61.26 us 44.77 us spinlock do_anonymous_page+0x16d 24 78.36 us 12.27 us 3.27 us mutex pipe_read+0x56 2 71.58 us 59.56 us 35.79 us spinlock __handle_mm_fault+0x6aa 6 25.68 us 6.89 us 4.28 us spinlock do_idle+0x28d 1 18.46 us 18.46 us 18.46 us rtmutex exec_fw_cmd+0x21b 3 15.25 us 6.26 us 5.08 us spinlock tick_do_update_jiffies64+0x2c Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220725183124.368304-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-07-25perf lock: Add lock aggregation enumNamhyung Kim
Introduce the aggr_mode variable to prepare a later code change. The default is LOCK_AGGR_ADDR which aggregates the result for the lock instances. When -t/--threads option is given, it'd be set to LOCK_AGGR_TASK. The LOCK_AGGR_CALLER is for the contention analysis and it'd aggregate the stat by comparing the callstacks. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220725183124.368304-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-07-25perf lock: Add flags field in the lock_statNamhyung Kim
For lock contention tracepoint analysis, it needs to keep the flags. As nr_readlock and nr_trylock fields are not used for it, let's make it a union. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220725183124.368304-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-07-21perf lock: Fix a copy-n-paste bugNamhyung Kim
It should be lock_text_end instead of _start. Fixes: 0d2997f750d1de39 ("perf lock: Look up callchain for the contended locks") Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220721043644.153718-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-07-12perf lock: Look up callchain for the contended locksNamhyung Kim
The lock contention tracepoints don't provide lock names. All we can do is to get stack traces and show the caller instead. To minimize the overhead it's limited to up to 8 stack traces and display the first non-lock function symbol name as a caller. $ perf lock report -F acquired,contended,avg_wait,wait_total Name acquired contended avg wait total wait update_blocked_a... 40 40 3.61 us 144.45 us kernfs_fop_open+... 5 5 3.64 us 18.18 us _nohz_idle_balance 3 3 2.65 us 7.95 us tick_do_update_j... 1 1 6.04 us 6.04 us ep_scan_ready_list 1 1 3.93 us 3.93 us ... Signed-off-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Ian Rogers <irogers@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220615163222.1275500-8-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-07-12perf lock: Handle lock contention tracepointsNamhyung Kim
When the lock contention events are used, there's no tracking of acquire and release. So the state machine is simplified to use UNINITIALIZED -> CONTENDED -> ACQUIRED only. Note that CONTENDED state is re-entrant since mutex locks can hit two or more consecutive contention_begin events for optimistic spinning and sleep. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Ian Rogers <irogers@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220615163222.1275500-6-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-07-12perf lock: Add lock contention tracepoints record supportNamhyung Kim
When LOCKDEP and LOCK_STAT events are not available, it falls back to record the new lock contention tracepoints. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220615163222.1275500-5-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-07-12perf lock: Skip print_bad_events() if nothing badNamhyung Kim
The debug output is meaningful when there are bad lock sequences. Skip it unless there's one or -v option is given. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220615163222.1275500-4-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-07-12perf lock: Allow to use different kernel symbolsNamhyung Kim
Add --vmlinux and --kallsyms options to support data file from different kernels. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220615163222.1275500-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-07-12perf lock: Print wait times with unitNamhyung Kim
Currently it only prints the time in nsec but it's a bit hard to read and takes longer in the screen. We can change it to use different units and keep the number small to save the space. Before: $ perf lock report Name acquired contended avg wait (ns) total wait (ns) max wait (ns) min wait (ns) jiffies_lock 433 32 2778 88908 13570 692 &lruvec->lru_lock 747 5 11254 56272 18317 1412 slock-AF_INET6 7 1 23543 23543 23543 23543 &newf->file_lock 706 15 1025 15388 2279 618 slock-AF_INET6 8 1 10379 10379 10379 10379 &rq->__lock 2143 5 2037 10185 3462 939 After: Name acquired contended avg wait total wait max wait min wait jiffies_lock 433 32 2.78 us 88.91 us 13.57 us 692 ns &lruvec->lru_lock 747 5 11.25 us 56.27 us 18.32 us 1.41 us slock-AF_INET6 7 1 23.54 us 23.54 us 23.54 us 23.54 us &newf->file_lock 706 15 1.02 us 15.39 us 2.28 us 618 ns slock-AF_INET6 8 1 10.38 us 10.38 us 10.38 us 10.38 us &rq->__lock 2143 5 2.04 us 10.19 us 3.46 us 939 ns Signed-off-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Ian Rogers <irogers@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20220615163222.1275500-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-06-03perf lock: Change to synthesize task eventsNamhyung Kim
With -t/--threads option, it needs to display task names so synthesize task related events at the beginning. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Acked-by: Ian Rogers <irogers@google.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Fixes: 7c3bcbdf449f ("perf lock: Add -t/--thread option for report") Link: http://lore.kernel.org/lkml/20220601065846.456965-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-05-23perf lock: Add -t/--thread option for reportNamhyung Kim
The -t option is to show per-thread lock stat like below: $ perf lock report -t -F acquired,contended,avg_wait Name acquired contended avg wait (ns) perf 240569 9 5784 swapper 106610 19 543 :15789 17370 2 14538 ContainerMgr 8981 6 874 sleep 5275 1 11281 ContainerThread 4416 4 944 RootPressureThr 3215 5 1215 rcu_preempt 2954 0 0 ContainerMgr 2560 0 0 unnamed 1873 0 0 EventManager_De 1845 1 636 futex-default-S 1609 0 0 ... Committer notes: Add that option to the 'perf lock report' man page. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20220521010811.932703-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-05-23perf lock: Do not discard broken lock statsNamhyung Kim
Currently it discards a lock_stat for a lock instance when there's a broken lock_seq_stat in a single task for the lock. But it also means that the existing (and later) valid lock stat info for that lock will be discarded as well. This is not ideal since we can lose many valuable info because of a single failure. Actually those failures are indepent to the existing stat. So we can only discard the broken lock_seq_stat but keep the valid lock_stat. The discarded lock_seq_stat will be reallocated in a subsequent event with SEQ_STATE_UNINITIALIZED which will be ignored until it see the start of the next sequence. So it should be ok just free it. Before: $ perf lock report -F acquired,contended,avg_wait Warning: Processed 1401603 events and lost 18 chunks! Check IO/CPU overload! Name acquired contended avg wait (ns) rcu_read_lock 251225 0 0 &(ei->i_block_re... 8731 0 0 &sb->s_type->i_l... 8731 0 0 hrtimer_bases.lock 5261 0 0 hrtimer_bases.lock 2626 0 0 hrtimer_bases.lock 1953 0 0 hrtimer_bases.lock 1382 0 0 cpu_hotplug_lock 1350 0 0 hrtimer_bases.lock 1273 0 0 hrtimer_bases.lock 1269 0 0 hrtimer_bases.lock 1198 0 0 ... New: Name acquired contended avg wait (ns) rcu_read_lock 251225 0 0 tk_core.seq.seqc... 54074 0 0 &xa->xa_lock 17470 0 0 &ei->i_es_lock 17464 0 0 &ei->i_raw_lock 9391 0 0 &mapping->privat... 8734 0 0 &ei->i_data_sem 8731 0 0 &(ei->i_block_re... 8731 0 0 &sb->s_type->i_l... 8731 0 0 jiffies_seq.seqc... 6953 0 0 &mm->mmap_lock 6889 0 0 balancing 5768 0 0 hrtimer_bases.lock 5261 0 0 ... Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20220521010811.932703-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-03-26perf tools: Enhance the matching of sub-commands abbreviationsWei Li
We support short command 'rec*' for 'record' and 'rep*' for 'report' in lots of sub-commands, but the matching is not quite strict currnetly. It may be puzzling sometime, like we mis-type a 'recport' to report but it will perform 'record' in fact without any message. To fix this, add a check to ensure that the short cmd is valid prefix of the real command. Committer testing: [root@quaco ~]# perf c2c re sleep 1 Usage: perf c2c {record|report} -v, --verbose be more verbose (show counter open errors, etc) # perf c2c rec sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.038 MB perf.data (16 samples) ] # perf c2c recport sleep 1 Usage: perf c2c {record|report} -v, --verbose be more verbose (show counter open errors, etc) # perf c2c record sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.038 MB perf.data (15 samples) ] # perf c2c records sleep 1 Usage: perf c2c {record|report} -v, --verbose be more verbose (show counter open errors, etc) # Signed-off-by: Wei Li <liwei391@huawei.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Hanjun Guo <guohanjun@huawei.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Rui Xiang <rui.xiang@huawei.com> Link: http://lore.kernel.org/lkml/20220325092032.2956161-1-liwei391@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-03-25perf lock: Add -F/--field option to control outputNamhyung Kim
The -F/--field option is to customize the list of fields to output: $ perf lock report -F contended,wait_max -k avg_wait Name contended max wait (ns) avg wait (ns) slock-AF_INET6 1 23543 23543 &lruvec->lru_lock 5 18317 11254 slock-AF_INET6 1 10379 10379 rcu_node_1 1 2104 2104 &dentry->d_lockr... 1 1844 1844 &dentry->d_lockr... 1 1672 1672 &newf->file_lock 15 2279 1025 &dentry->d_lockr... 1 792 792 Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20220323230259.288494-3-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-03-25perf lock: Extend struct lock_key to have print functionNamhyung Kim
And use it to print output for each key field. No functional change intended and the output should be identical. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20220323230259.288494-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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