diff options
| author | Tang Yizhou <yizhou.tang@shopee.com> | 2025-03-04 19:03:18 +0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-03-17 00:05:37 -0700 |
| commit | 6cc4c3aa714bc58ec5d20f3054ca5f23534984d1 (patch) | |
| tree | 74a7bfe20c7876fe132d5d1317c631b2be2f6ea5 | |
| parent | 28c24ef9e04f95672b72b1297eff7dae91cceea8 (diff) | |
writeback: fix calculations in trace_balance_dirty_pages() for cgwb
In the commit dcc25ae76eb7 ("writeback: move global_dirty_limit into
wb_domain") of the cgroup writeback backpressure propagation patchset,
Tejun made some adaptations to trace_balance_dirty_pages() for cgroup
writeback. However, this adaptation was incomplete and Tejun missed
further adaptation in the subsequent patches.
In the cgroup writeback scenario, if sdtc in balance_dirty_pages() is
assigned to mdtc, then upon entering trace_balance_dirty_pages(),
__entry->limit should be assigned based on the dirty_limit of the
corresponding memcg's wb_domain, rather than global_wb_domain.
To address this issue and simplify the implementation, introduce a 'limit'
field in struct dirty_throttle_control to store the hard_limit value
computed in wb_position_ratio() by calling hard_dirty_limit(). This field
will then be used in trace_balance_dirty_pages() to assign the value to
__entry->limit.
Link: https://lkml.kernel.org/r/20250304110318.159567-4-yizhou.tang@shopee.com
Fixes: dcc25ae76eb7 ("writeback: move global_dirty_limit into wb_domain")
Signed-off-by: Tang Yizhou <yizhou.tang@shopee.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | include/linux/writeback.h | 1 | ||||
| -rw-r--r-- | include/trace/events/writeback.h | 5 | ||||
| -rw-r--r-- | mm/page-writeback.c | 2 |
3 files changed, 4 insertions, 4 deletions
diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 32095928365c..58bda3347914 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -326,6 +326,7 @@ struct dirty_throttle_control { unsigned long dirty; /* file_dirty + write + nfs */ unsigned long thresh; /* dirty threshold */ unsigned long bg_thresh; /* dirty background threshold */ + unsigned long limit; /* hard dirty limit */ unsigned long wb_dirty; /* per-wb counterparts */ unsigned long wb_thresh; diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index 3046ca6b08ea..0ff388131fc9 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -663,9 +663,8 @@ TRACE_EVENT(balance_dirty_pages, unsigned long freerun = (dtc->thresh + dtc->bg_thresh) / 2; strscpy_pad(__entry->bdi, bdi_dev_name(wb->bdi), 32); - __entry->limit = global_wb_domain.dirty_limit; - __entry->setpoint = (global_wb_domain.dirty_limit + - freerun) / 2; + __entry->limit = dtc->limit; + __entry->setpoint = (dtc->limit + freerun) / 2; __entry->dirty = dtc->dirty; __entry->wb_setpoint = __entry->setpoint * dtc->wb_thresh / (dtc->thresh + 1); diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 149f8b815904..18456ddd463b 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1072,7 +1072,7 @@ static void wb_position_ratio(struct dirty_throttle_control *dtc) struct bdi_writeback *wb = dtc->wb; unsigned long write_bw = READ_ONCE(wb->avg_write_bandwidth); unsigned long freerun = dirty_freerun_ceiling(dtc->thresh, dtc->bg_thresh); - unsigned long limit = hard_dirty_limit(dtc_dom(dtc), dtc->thresh); + unsigned long limit = dtc->limit = hard_dirty_limit(dtc_dom(dtc), dtc->thresh); unsigned long wb_thresh = dtc->wb_thresh; unsigned long x_intercept; unsigned long setpoint; /* dirty pages' target balance point */ |