The patch titled
writeback: account for time spent congestion_waited
has been added to the -mm tree. Its filename is
writeback-account-for-time-spent-congestion_waited.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: writeback: account for time spent congestion_waited
From: Mel Gorman <mel@xxxxxxxxx>
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@xxxxxxxxx>
Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx>
Reviewed-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/trace/events/writeback.h | 28 ++++++++++++++++++++++++++++
mm/backing-dev.c | 5 +++++
2 files changed, 33 insertions(+)
diff -puN include/trace/events/writeback.h~writeback-account-for-time-spent-congestion_waited include/trace/events/writeback.h
--- a/include/trace/events/writeback.h~writeback-account-for-time-spent-congestion_waited
+++ a/include/trace/events/writeback.h
@@ -151,6 +151,34 @@ DEFINE_WBC_EVENT(wbc_balance_dirty_writt
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 -puN mm/backing-dev.c~writeback-account-for-time-spent-congestion_waited mm/backing-dev.c
--- a/mm/backing-dev.c~writeback-account-for-time-spent-congestion_waited
+++ a/mm/backing-dev.c
@@ -762,12 +762,17 @@ 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);
_
Patches currently in -mm which might be from mel@xxxxxxxxx are
include-linux-pageblock-flagsh-fix-set_pageblock_flags-macro-definiton.patch
mm-compaction-fix-compactpagefailed-counting.patch
memory-hotplug-fix-notifiers-return-value-check.patch
memory-hotplug-unify-is_removable-and-offline-detection-code.patch
mm-fix-typo-in-mmh-when-node_not_in_page_flags.patch
tracing-vmscan-add-trace-events-for-lru-list-shrinking.patch
writeback-account-for-time-spent-congestion_waited.patch
vmscan-synchronous-lumpy-reclaim-should-not-call-congestion_wait.patch
vmscan-narrow-the-scenarios-lumpy-reclaim-uses-synchrounous-reclaim.patch
vmscan-remove-dead-code-in-shrink_inactive_list.patch
vmscan-isolated_lru_pages-stop-neighbour-search-if-neighbour-cannot-be-isolated.patch
writeback-do-not-sleep-on-the-congestion-queue-if-there-are-no-congested-bdis.patch
writeback-do-not-sleep-on-the-congestion-queue-if-there-are-no-congested-bdis-or-if-significant-congestion-is-not-being-encountered-in-the-current-zone.patch
delay-accounting-re-implement-c-for-getdelaysc-to-report-information-on-a-target-command.patch
delay-accounting-re-implement-c-for-getdelaysc-to-report-information-on-a-target-command-checkpatch-fixes.patch
add-debugging-aid-for-memory-initialisation-problems.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
