The patch titled
writeback-bdi-write-bandwidth-estimation-fix
has been added to the -mm tree. Its filename is
writeback-bdi-write-bandwidth-estimation-fix.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-bdi-write-bandwidth-estimation-fix
From: Wu Fengguang <fengguang.wu@xxxxxxxxx>
As suggested by Andrew and Peter:
I do recall hearing of people who set HZ very low, perhaps because their
huge machines were seeing performance prolems when the timer tick went
off. Probably there's no need to do that any more.
But still, we shouldn't hard-wire the (HZ >= 100) assumption if we don't
absolutely need to, and I don't think it is absolutely needed here.
People who do cpu bring-up on very slow FPGAs also lower HZ as far as
possible.
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Cc: Chris Mason <chris.mason@xxxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Li Shaohua <shaohua.li@xxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Cc: Richard Kennedy <richard@xxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Michael Rubin <mrubin@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page-writeback.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff -puN mm/page-writeback.c~writeback-bdi-write-bandwidth-estimation-fix mm/page-writeback.c
--- a/mm/page-writeback.c~writeback-bdi-write-bandwidth-estimation-fix
+++ a/mm/page-writeback.c
@@ -483,6 +483,7 @@ void bdi_update_write_bandwidth(struct b
unsigned long *bw_time,
s64 *bw_written)
{
+ const unsigned long unit_time = max(HZ/100, 1);
unsigned long written;
unsigned long elapsed;
unsigned long bw;
@@ -492,7 +493,7 @@ void bdi_update_write_bandwidth(struct b
goto snapshot;
elapsed = jiffies - *bw_time;
- if (elapsed < HZ/100)
+ if (elapsed < unit_time)
return;
/*
@@ -506,7 +507,7 @@ void bdi_update_write_bandwidth(struct b
written = percpu_counter_read(&bdi->bdi_stat[BDI_WRITTEN]) - *bw_written;
bw = (HZ * PAGE_CACHE_SIZE * written + elapsed/2) / elapsed;
- w = min(elapsed / (HZ/100), 128UL);
+ w = min(elapsed / unit_time, 128UL);
bdi->write_bandwidth = (bdi->write_bandwidth * (1024-w) + bw * w) >> 10;
bdi->write_bandwidth_update_time = jiffies;
snapshot:
_
Patches currently in -mm which might be from fengguang.wu@xxxxxxxxx are
linux-next.patch
mm-remove-call-to-find_vma-in-pagewalk-for-non-hugetlbfs.patch
writeback-integrated-background-writeback-work.patch
writeback-trace-wakeup-event-for-background-writeback.patch
writeback-stop-background-kupdate-works-from-livelocking-other-works.patch
writeback-stop-background-kupdate-works-from-livelocking-other-works-update.patch
writeback-avoid-livelocking-wb_sync_all-writeback.patch
writeback-avoid-livelocking-wb_sync_all-writeback-update.patch
writeback-check-skipped-pages-on-wb_sync_all.patch
writeback-check-skipped-pages-on-wb_sync_all-update.patch
writeback-check-skipped-pages-on-wb_sync_all-update-fix.patch
writeback-io-less-balance_dirty_pages.patch
writeback-consolidate-variable-names-in-balance_dirty_pages.patch
writeback-per-task-rate-limit-on-balance_dirty_pages.patch
writeback-per-task-rate-limit-on-balance_dirty_pages-fix.patch
writeback-prevent-duplicate-balance_dirty_pages_ratelimited-calls.patch
writeback-account-per-bdi-accumulated-written-pages.patch
writeback-bdi-write-bandwidth-estimation.patch
writeback-bdi-write-bandwidth-estimation-fix.patch
writeback-show-bdi-write-bandwidth-in-debugfs.patch
writeback-quit-throttling-when-bdi-dirty-pages-dropped-low.patch
writeback-reduce-per-bdi-dirty-threshold-ramp-up-time.patch
writeback-make-reasonable-gap-between-the-dirty-background-thresholds.patch
writeback-scale-down-max-throttle-bandwidth-on-concurrent-dirtiers.patch
writeback-add-trace-event-for-balance_dirty_pages.patch
writeback-make-nr_to_write-a-per-file-limit.patch
writeback-make-nr_to_write-a-per-file-limit-fix.patch
mm-page-writebackc-fix-__set_page_dirty_no_writeback-return-value.patch
mm-find_get_pages_contig-fixlet.patch
mm-smaps-export-mlock-information.patch
memcg-add-page_cgroup-flags-for-dirty-page-tracking.patch
memcg-document-cgroup-dirty-memory-interfaces.patch
memcg-document-cgroup-dirty-memory-interfaces-fix.patch
memcg-create-extensible-page-stat-update-routines.patch
memcg-add-lock-to-synchronize-page-accounting-and-migration.patch
memcg-use-zalloc-rather-than-mallocmemset.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
