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authorWu Fengguang <fengguang.wu@intel.com>2011-06-11 19:25:42 -0600
committerWu Fengguang <fengguang.wu@intel.com>2011-12-18 14:20:27 +0800
commit83712358ba0a1497ce59a4f84ce4dd0f803fe6fc (patch)
treed17ab27a7bff50616e3b63ad137c004d9ccfbcb0 /include/trace
parent32c7f202a4801252a0f3578807b75a961f792870 (diff)
downloadlinux-linaro-stable-83712358ba0a1497ce59a4f84ce4dd0f803fe6fc.tar.gz
writeback: dirty ratelimit - think time compensation
Compensate the task's think time when computing the final pause time, so that ->dirty_ratelimit can be executed accurately. think time := time spend outside of balance_dirty_pages() In the rare case that the task slept longer than the 200ms period time (result in negative pause time), the sleep time will be compensated in the following periods, too, if it's less than 1 second. Accumulated errors are carefully avoided as long as the max pause area is not hitted. Pseudo code: period = pages_dirtied / task_ratelimit; think = jiffies - dirty_paused_when; pause = period - think; 1) normal case: period > think pause = period - think dirty_paused_when = jiffies + pause nr_dirtied = 0 period time |===============================>| think time pause time |===============>|==============>| ------|----------------|---------------|------------------------ dirty_paused_when jiffies 2) no pause case: period <= think don't pause; reduce future pause time by: dirty_paused_when += period nr_dirtied = 0 period time |===============================>| think time |===================================================>| ------|--------------------------------+-------------------|---- dirty_paused_when jiffies Acked-by: Jan Kara <jack@suse.cz> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Diffstat (limited to 'include/trace')
-rw-r--r--include/trace/events/writeback.h14
1 files changed, 11 insertions, 3 deletions
diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index 99d1d0decf88..8588a8918023 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -300,12 +300,13 @@ TRACE_EVENT(balance_dirty_pages,
unsigned long dirty_ratelimit,
unsigned long task_ratelimit,
unsigned long dirtied,
+ unsigned long period,
long pause,
unsigned long start_time),
TP_ARGS(bdi, thresh, bg_thresh, dirty, bdi_thresh, bdi_dirty,
dirty_ratelimit, task_ratelimit,
- dirtied, pause, start_time),
+ dirtied, period, pause, start_time),
TP_STRUCT__entry(
__array( char, bdi, 32)
@@ -320,6 +321,8 @@ TRACE_EVENT(balance_dirty_pages,
__field(unsigned int, dirtied_pause)
__field(unsigned long, paused)
__field( long, pause)
+ __field(unsigned long, period)
+ __field( long, think)
),
TP_fast_assign(
@@ -336,6 +339,9 @@ TRACE_EVENT(balance_dirty_pages,
__entry->task_ratelimit = KBps(task_ratelimit);
__entry->dirtied = dirtied;
__entry->dirtied_pause = current->nr_dirtied_pause;
+ __entry->think = current->dirty_paused_when == 0 ? 0 :
+ (long)(jiffies - current->dirty_paused_when) * 1000/HZ;
+ __entry->period = period * 1000 / HZ;
__entry->pause = pause * 1000 / HZ;
__entry->paused = (jiffies - start_time) * 1000 / HZ;
),
@@ -346,7 +352,7 @@ TRACE_EVENT(balance_dirty_pages,
"bdi_setpoint=%lu bdi_dirty=%lu "
"dirty_ratelimit=%lu task_ratelimit=%lu "
"dirtied=%u dirtied_pause=%u "
- "paused=%lu pause=%ld",
+ "paused=%lu pause=%ld period=%lu think=%ld",
__entry->bdi,
__entry->limit,
__entry->setpoint,
@@ -358,7 +364,9 @@ TRACE_EVENT(balance_dirty_pages,
__entry->dirtied,
__entry->dirtied_pause,
__entry->paused, /* ms */
- __entry->pause /* ms */
+ __entry->pause, /* ms */
+ __entry->period, /* ms */
+ __entry->think /* ms */
)
);