perf intel-pt: Do not default to recording all switch events

On systems with many CPUs, recording extra context switch events can be
excessive and unnecessary. Add perf config intel-pt.all-switch-events=false
to control the behaviour.

Example:

 # perf config intel-pt.all-switch-events=false
 # perf record -eintel_pt//u uname
 Linux
 [ perf record: Woken up 1 times to write data ]
 [ perf record: Captured and wrote 0.082 MB perf.data ]
 # perf script -D | grep PERF_RECORD_SWITCH | awk '{print $5}' | uniq -c
       5 PERF_RECORD_SWITCH
 # perf config intel-pt.all-switch-events=true
 # perf record -eintel_pt//u uname
 Linux
 [ perf record: Woken up 1 times to write data ]
 [ perf record: Captured and wrote 0.102 MB perf.data ]
 # perf script -D | grep PERF_RECORD_SWITCH | awk '{print $5}' | uniq -c
     180 PERF_RECORD_SWITCH_CPU_WIDE

Committer testing:

While doing a make -j28 allmodconfig:

  root@five:~# grep "model name" -m1 /proc/cpuinfo
  model name	: Intel(R) Core(TM) i7-14700K
  root@five:~#
  root@five:~# perf config intel-pt.all-switch-events=false
  root@five:~# perf record -e intel_pt//u uname
  Linux
  [ perf record: Woken up 2 times to write data ]
  [ perf record: Captured and wrote 0.019 MB perf.data ]
  root@five:~# perf report --stats | grep SWITCH_CPU_WIDE
  root@five:~#
  root@five:~# perf config intel-pt.all-switch-events=true
  root@five:~# perf record -e intel_pt//u uname
  Linux
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.047 MB perf.data ]
  root@five:~# perf report --stats | grep SWITCH_CPU_WIDE
       SWITCH_CPU_WIDE events:        542  (96.4%)
  root@five:~#

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20250512093932.79854-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

0 files changed, 0 insertions, 0 deletions