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| author | Mel Gorman <mel@csn.ul.ie> | 2010-10-26 23:21:41 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-10-27 01:52:07 +0200 |
| commit | 52bb9198668968506f9d12bf35d7f5d3f094921e (patch) | |
| tree | 6e1f79c46de902c4462054803eb13115673f8c8c | |
| parent | tracing, vmscan: add trace events for LRU list shrinking (diff) | |
| download | linux-52bb9198668968506f9d12bf35d7f5d3f094921e.tar.xz linux-52bb9198668968506f9d12bf35d7f5d3f094921e.zip | |
writeback: account for time spent congestion_waited
There is strong evidence to indicate a lot of time is being spent in
congestion_wait(), some of it unnecessarily. This patch adds a tracepoint
for congestion_wait to record when congestion_wait() was called, how long
the timeout was for and how long it actually slept.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/trace/events/writeback.h | 28 | ||||
| -rw-r--r-- | mm/backing-dev.c | 5 |
2 files changed, 33 insertions, 0 deletions
diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index 0bb01ab2e984..d2b2654606ec 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -151,6 +151,34 @@ DEFINE_WBC_EVENT(wbc_balance_dirty_written); DEFINE_WBC_EVENT(wbc_balance_dirty_wait); DEFINE_WBC_EVENT(wbc_writepage); +DECLARE_EVENT_CLASS(writeback_congest_waited_template, + + TP_PROTO(unsigned int usec_timeout, unsigned int usec_delayed), + + TP_ARGS(usec_timeout, usec_delayed), + + TP_STRUCT__entry( + __field( unsigned int, usec_timeout ) + __field( unsigned int, usec_delayed ) + ), + + TP_fast_assign( + __entry->usec_timeout = usec_timeout; + __entry->usec_delayed = usec_delayed; + ), + + TP_printk("usec_timeout=%u usec_delayed=%u", + __entry->usec_timeout, + __entry->usec_delayed) +); + +DEFINE_EVENT(writeback_congest_waited_template, writeback_congestion_wait, + + TP_PROTO(unsigned int usec_timeout, unsigned int usec_delayed), + + TP_ARGS(usec_timeout, usec_delayed) +); + #endif /* _TRACE_WRITEBACK_H */ /* This part must be outside protection */ diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 65d420499a61..55627306abe0 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -764,12 +764,17 @@ EXPORT_SYMBOL(set_bdi_congested); long congestion_wait(int sync, long timeout) { long ret; + unsigned long start = jiffies; DEFINE_WAIT(wait); wait_queue_head_t *wqh = &congestion_wqh[sync]; prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); ret = io_schedule_timeout(timeout); finish_wait(wqh, &wait); + + trace_writeback_congestion_wait(jiffies_to_usecs(timeout), + jiffies_to_usecs(jiffies - start)); + return ret; } EXPORT_SYMBOL(congestion_wait); |