From: Wu Fengguang <fengguang.wu@intel.com>
To: linux-mm <linux-mm@kvack.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Wu Fengguang <fengguang.wu@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Theodore Ts'o <tytso@mit.edu>, Dave Chinner <david@fromorbit.com>,
Jan Kara <jack@suse.cz>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
Mel Gorman <mel@csn.ul.ie>, Rik van Riel <riel@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Chris Mason <chris.mason@oracle.com>,
Christoph Hellwig <hch@lst.de>, Li Shaohua <shaohua.li@intel.com>
Subject: [PATCH 07/17] writeback: add trace event for balance_dirty_pages()
Date: Sun, 12 Sep 2010 23:49:52 +0800 [thread overview]
Message-ID: <20100912155203.668993282@intel.com> (raw)
In-Reply-To: 20100912154945.758129106@intel.com
[-- Attachment #1: writeback-trace-balance_dirty_pages.patch --]
[-- Type: text/plain, Size: 5741 bytes --]
Here is an interesting test to verify the theory with balance_dirty_pages()
tracing. On a partition that can do ~60MB/s, a sparse file is created and
4 rsync tasks with different write bandwidth started:
dd if=/dev/zero of=/mnt/1T bs=1M count=1 seek=1024000
echo 1 > /debug/tracing/events/writeback/balance_dirty_pages/enable
rsync localhost:/mnt/1T /mnt/a --bwlimit 10000&
rsync localhost:/mnt/1T /mnt/A --bwlimit 10000&
rsync localhost:/mnt/1T /mnt/b --bwlimit 20000&
rsync localhost:/mnt/1T /mnt/c --bwlimit 30000&
(btw, is there a dd that can do --bwlimit?
it's a bit twisted to use rsync, or lftp net:limit-rate)
Trace outputs within 0.1 second, grouped by tasks:
rsync-3824 [004] 15002.076447: balance_dirty_pages: bdi=btrfs-2 weight=15% thresh=130876 gap=5340 dirtied=192 pause=20 bw=34855512
rsync-3822 [003] 15002.091701: balance_dirty_pages: bdi=btrfs-2 weight=15% thresh=130777 gap=5113 dirtied=192 pause=20 bw=33419085
rsync-3821 [006] 15002.004667: balance_dirty_pages: bdi=btrfs-2 weight=30% thresh=129570 gap=3714 dirtied=64 pause=8 bw=24541625
rsync-3821 [006] 15002.012654: balance_dirty_pages: bdi=btrfs-2 weight=30% thresh=129589 gap=3733 dirtied=64 pause=8 bw=24651878
rsync-3821 [006] 15002.021838: balance_dirty_pages: bdi=btrfs-2 weight=30% thresh=129604 gap=3748 dirtied=64 pause=8 bw=24768628
rsync-3821 [004] 15002.091193: balance_dirty_pages: bdi=btrfs-2 weight=29% thresh=129583 gap=3983 dirtied=64 pause=8 bw=26274370
rsync-3821 [004] 15002.102729: balance_dirty_pages: bdi=btrfs-2 weight=29% thresh=129594 gap=3802 dirtied=64 pause=8 bw=25015422
rsync-3821 [000] 15002.109252: balance_dirty_pages: bdi=btrfs-2 weight=29% thresh=129619 gap=3827 dirtied=64 pause=8 bw=25179342
rsync-3823 [002] 15002.009029: balance_dirty_pages: bdi=btrfs-2 weight=39% thresh=128762 gap=2842 dirtied=64 pause=12 bw=18885024
rsync-3823 [002] 15002.021598: balance_dirty_pages: bdi=btrfs-2 weight=39% thresh=128813 gap=3021 dirtied=64 pause=12 bw=20088241
rsync-3823 [003] 15002.032973: balance_dirty_pages: bdi=btrfs-2 weight=39% thresh=128805 gap=2885 dirtied=64 pause=12 bw=19146453
rsync-3823 [003] 15002.048800: balance_dirty_pages: bdi=btrfs-2 weight=39% thresh=128823 gap=2967 dirtied=64 pause=12 bw=19673334
rsync-3823 [003] 15002.060728: balance_dirty_pages: bdi=btrfs-2 weight=39% thresh=128821 gap=3221 dirtied=64 pause=12 bw=21362280
rsync-3823 [000] 15002.073152: balance_dirty_pages: bdi=btrfs-2 weight=39% thresh=128825 gap=3225 dirtied=64 pause=12 bw=21385010
rsync-3823 [005] 15002.090111: balance_dirty_pages: bdi=btrfs-2 weight=39% thresh=128782 gap=3214 dirtied=64 pause=12 bw=21333266
rsync-3823 [004] 15002.102520: balance_dirty_pages: bdi=btrfs-2 weight=39% thresh=128764 gap=3036 dirtied=64 pause=12 bw=20104559
The data vividly show that
- the heaviest writer is throttled a bit (weight=39%)
- the lighter writers run at full speed (weight=15%,15%,30%)
rsync is smart enough to compensate for the in-kernel pause time
Don't be confused by the 'bw=' field. It does not take user space
think time into account.
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
include/trace/events/writeback.h | 47 +++++++++++++++++++++++++++--
mm/page-writeback.c | 5 +++
2 files changed, 49 insertions(+), 3 deletions(-)
--- linux-next.orig/include/trace/events/writeback.h 2010-09-07 23:16:28.000000000 +0800
+++ linux-next/include/trace/events/writeback.h 2010-09-07 23:20:17.000000000 +0800
@@ -148,11 +148,52 @@ DEFINE_EVENT(wbc_class, name, \
DEFINE_WBC_EVENT(wbc_writeback_start);
DEFINE_WBC_EVENT(wbc_writeback_written);
DEFINE_WBC_EVENT(wbc_writeback_wait);
-DEFINE_WBC_EVENT(wbc_balance_dirty_start);
-DEFINE_WBC_EVENT(wbc_balance_dirty_written);
-DEFINE_WBC_EVENT(wbc_balance_dirty_wait);
DEFINE_WBC_EVENT(wbc_writepage);
+TRACE_EVENT(balance_dirty_pages,
+
+ TP_PROTO(struct backing_dev_info *bdi,
+ unsigned long task_weight,
+ unsigned long bdi_thresh,
+ unsigned long gap,
+ unsigned long bw,
+ unsigned long pages_dirtied,
+ unsigned long pause),
+
+ TP_ARGS(bdi, task_weight, bdi_thresh, gap, bw, pages_dirtied, pause),
+
+ TP_STRUCT__entry(
+ __array(char, bdi, 32)
+ __field(unsigned long, task_weight)
+ __field(unsigned long, bdi_thresh)
+ __field(unsigned long, gap)
+ __field(unsigned long, bw)
+ __field(unsigned long, pages_dirtied)
+ __field(unsigned long, pause)
+ ),
+
+ TP_fast_assign(
+ strlcpy(__entry->bdi, dev_name(bdi->dev), 32);
+ __entry->task_weight = task_weight;
+ __entry->bdi_thresh = bdi_thresh;
+ __entry->gap = gap;
+ __entry->bw = bw;
+ __entry->pages_dirtied = pages_dirtied;
+ __entry->pause = pause * 1000 / HZ;
+ ),
+
+ TP_printk("bdi=%s weight=%lu%% "
+ "thresh=%lu gap=%lu dirtied=%lu pause=%lu bw=%lu",
+ __entry->bdi,
+ __entry->task_weight,
+ __entry->bdi_thresh,
+ __entry->gap,
+ __entry->pages_dirtied,
+ __entry->pause,
+ __entry->bw
+ )
+);
+
#endif /* _TRACE_WRITEBACK_H */
/* This part must be outside protection */
--- linux-next.orig/mm/page-writeback.c 2010-09-07 23:20:02.000000000 +0800
+++ linux-next/mm/page-writeback.c 2010-09-07 23:21:58.000000000 +0800
@@ -536,6 +536,11 @@ static void balance_dirty_pages(struct a
} else if (pause < HZ/100)
current->nr_dirtied_pause++;
+ trace_balance_dirty_pages(bdi,
+ 100 * numerator / denominator,
+ bdi_thresh, gap, bw,
+ pages_dirtied, pause);
+
__set_current_state(TASK_INTERRUPTIBLE);
io_schedule_timeout(pause);
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2010-09-12 15:55 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-12 15:49 [PATCH 00/17] [RFC] soft and dynamic dirty throttling limits Wu Fengguang
2010-09-12 15:49 ` [PATCH 01/17] writeback: remove the internal 5% low bound on dirty_ratio Wu Fengguang
2010-09-13 9:23 ` Johannes Weiner
2010-09-13 9:51 ` Mel Gorman
2010-09-13 9:57 ` Wu Fengguang
2010-09-13 10:10 ` Mel Gorman
2010-09-12 15:49 ` [PATCH 02/17] writeback: IO-less balance_dirty_pages() Wu Fengguang
2010-09-13 8:45 ` Dave Chinner
2010-09-13 11:38 ` Wu Fengguang
2010-09-12 15:49 ` [PATCH 03/17] writeback: per-task rate limit to balance_dirty_pages() Wu Fengguang
2010-09-12 15:49 ` [PATCH 04/17] writeback: quit throttling when bdi dirty/writeback pages go down Wu Fengguang
2010-09-12 15:49 ` [PATCH 05/17] writeback: quit throttling when signal pending Wu Fengguang
2010-09-12 20:46 ` Neil Brown
2010-09-13 1:55 ` Wu Fengguang
2010-09-13 3:21 ` Neil Brown
2010-09-13 3:48 ` Wu Fengguang
2010-09-14 8:23 ` KOSAKI Motohiro
2010-09-14 8:33 ` Wu Fengguang
2010-09-14 8:44 ` KOSAKI Motohiro
2010-09-14 9:17 ` Wu Fengguang
2010-09-14 9:25 ` KOSAKI Motohiro
2010-09-12 15:49 ` [PATCH 06/17] writeback: move task dirty fraction to balance_dirty_pages() Wu Fengguang
2010-09-12 15:49 ` Wu Fengguang [this message]
2010-09-12 15:49 ` [PATCH 08/17] writeback: account per-bdi accumulated written pages Wu Fengguang
2010-09-12 15:59 ` Wu Fengguang
2010-09-14 8:32 ` KOSAKI Motohiro
2010-09-12 15:49 ` [PATCH 09/17] writeback: bdi write bandwidth estimation Wu Fengguang
2010-09-12 15:49 ` [PATCH 10/17] writeback: show bdi write bandwidth in debugfs Wu Fengguang
2010-09-12 15:49 ` [PATCH 11/17] writeback: make nr_to_write a per-file limit Wu Fengguang
2010-09-12 15:49 ` [PATCH 12/17] writeback: scale IO chunk size up to device bandwidth Wu Fengguang
2010-09-12 15:49 ` [PATCH 13/17] writeback: reduce per-bdi dirty threshold ramp up time Wu Fengguang
2010-09-12 16:15 ` Wu Fengguang
2010-09-12 15:49 ` [PATCH 14/17] vmscan: add scan_control.priority Wu Fengguang
2010-09-12 15:50 ` [PATCH 15/17] mm: lower soft dirty limits on memory pressure Wu Fengguang
2010-09-13 9:40 ` Wu Fengguang
2010-09-12 15:50 ` [PATCH 16/17] mm: create /vm/dirty_pressure in debugfs Wu Fengguang
2010-09-12 15:50 ` [PATCH 17/17] writeback: consolidate balance_dirty_pages() variable names Wu Fengguang
2010-10-12 14:17 ` [PATCH 00/17] [RFC] soft and dynamic dirty throttling limits Christoph Hellwig
2010-10-13 3:07 ` Dave Chinner
2010-10-13 3:23 ` Wu Fengguang
2010-10-13 8:26 ` Wu Fengguang
2010-10-13 9:26 ` Dave Chinner
2010-11-01 6:24 ` Dave Chinner
2010-11-04 3:41 ` Wu Fengguang
2010-11-04 12:48 ` Dave Chinner
2010-11-04 13:12 ` Christoph Hellwig
2010-11-05 14:56 ` Wu Fengguang
2010-11-06 10:42 ` Dave Chinner
2010-10-14 13:12 ` Wu Fengguang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20100912155203.668993282@intel.com \
--to=fengguang.wu@intel.com \
--cc=a.p.zijlstra@chello.nl \
--cc=akpm@linux-foundation.org \
--cc=chris.mason@oracle.com \
--cc=david@fromorbit.com \
--cc=hch@lst.de \
--cc=jack@suse.cz \
--cc=kosaki.motohiro@jp.fujitsu.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mel@csn.ul.ie \
--cc=riel@redhat.com \
--cc=shaohua.li@intel.com \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).