From: Wu Fengguang <fengguang.wu@intel.com>
To: Peter Staubach <staubach@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Theodore Tso <tytso@mit.edu>,
Christoph Hellwig <hch@infradead.org>,
Dave Chinner <david@fromorbit.com>,
Chris Mason <chris.mason@oracle.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
"Li, Shaohua" <shaohua.li@intel.com>,
Myklebust Trond <Trond.Myklebust@netapp.com>,
"jens.axboe@oracle.com" <jens.axboe@oracle.com>,
Jan Kara <jack@suse.cz>, Nick Piggin <npiggin@suse.de>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 00/45] some writeback experiments
Date: Thu, 8 Oct 2009 13:33:35 +0800 [thread overview]
Message-ID: <20091008053335.GA19458@localhost> (raw)
In-Reply-To: <20091007151822.GA9574@localhost>
On Wed, Oct 07, 2009 at 11:18:22PM +0800, Wu Fengguang wrote:
> On Wed, Oct 07, 2009 at 09:47:14PM +0800, Peter Staubach wrote:
> >
> > > # vmmon -d 1 nr_writeback nr_dirty nr_unstable # (per 1-second samples)
> > > nr_writeback nr_dirty nr_unstable
> > > 11227 41463 38044
> > > 11227 41463 38044
> > > 11227 41463 38044
> > > 11227 41463 38044
>
> I guess in the above 4 seconds, either client or (more likely) server
> is blocked. A blocked server cannot send ACKs to knock down both
Yeah the server side is blocked. The nfsd are mostly blocked in
generic_file_aio_write(), in particular, the i_mutex lock! I'm copying
one or two big files over NFS, so the i_mutex lock is heavily contented.
I'm using the default wsize=4096 for NFS-root..
wfg ~% ps -o pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:24,comm ax|g nfs
329 329 TS - -5 24 1 0.0 S< worker_thread nfsiod
4690 4690 TS - -5 24 0 0.1 D< generic_file_aio_write nfsd
4691 4691 TS - -5 24 0 0.0 D< generic_file_aio_write nfsd
4692 4692 TS - -5 24 0 0.0 D< generic_file_aio_write nfsd
4693 4693 TS - -5 24 0 0.0 D< generic_file_aio_write nfsd
4694 4694 TS - -5 24 0 0.1 D< generic_file_aio_write nfsd
4695 4695 TS - -5 24 1 0.1 D< generic_file_aio_write nfsd
4696 4696 TS - -5 24 1 0.0 D< log_wait_commit nfsd
4697 4697 TS - -5 24 0 0.0 D< generic_file_aio_write nfsd
wfg ~% ps -o pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:24,comm ax|g nfs
329 329 TS - -5 24 1 0.0 S< worker_thread nfsiod
4690 4690 TS - -5 24 0 0.1 D< generic_file_aio_write nfsd
4691 4691 TS - -5 24 0 0.0 D< generic_file_aio_write nfsd
4692 4692 TS - -5 24 0 0.0 D< generic_file_aio_write nfsd
4693 4693 TS - -5 24 0 0.0 D< sync_buffer nfsd
4694 4694 TS - -5 24 0 0.1 D< generic_file_aio_write nfsd
4695 4695 TS - -5 24 1 0.1 D< generic_file_aio_write nfsd
4696 4696 TS - -5 24 1 0.0 D< generic_file_aio_write nfsd
4697 4697 TS - -5 24 0 0.0 D< generic_file_aio_write nfsd
wfg ~% ps -o pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:24,comm ax|g nfs
329 329 TS - -5 24 1 0.0 S< worker_thread nfsiod
4690 4690 TS - -5 24 0 0.1 D< generic_file_aio_write nfsd
4691 4691 TS - -5 24 0 0.1 D< get_request_wait nfsd
4692 4692 TS - -5 24 0 0.1 D< generic_file_aio_write nfsd
4693 4693 TS - -5 24 0 0.1 S< svc_recv nfsd
4694 4694 TS - -5 24 0 0.1 D< generic_file_aio_write nfsd
4695 4695 TS - -5 24 0 0.1 D< generic_file_aio_write nfsd
4696 4696 TS - -5 24 0 0.1 S< svc_recv nfsd
4697 4697 TS - -5 24 1 0.1 D< generic_file_aio_write nfsd
wfg ~% ps -o pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:24,comm ax|g nfs
329 329 TS - -5 24 1 0.0 S< worker_thread nfsiod
4690 4690 TS - -5 24 1 0.1 D< get_write_access nfsd
4691 4691 TS - -5 24 0 0.1 D< generic_file_aio_write nfsd
4692 4692 TS - -5 24 0 0.1 D< generic_file_aio_write nfsd
4693 4693 TS - -5 24 1 0.1 D< generic_file_aio_write nfsd
4694 4694 TS - -5 24 1 0.1 D< get_write_access nfsd
4695 4695 TS - -5 24 0 0.1 D< generic_file_aio_write nfsd
4696 4696 TS - -5 24 0 0.1 D< generic_file_aio_write nfsd
4697 4697 TS - -5 24 0 0.1 D< generic_file_aio_write nfsd
Thanks,
Fengguang
> nr_writeback/nr_unstable. And the stuck nr_writeback will freeze
> nr_dirty as well, because the dirtying process is throttled until
> it receives enough "PG_writeback cleared" event, however the bdi-flush
> thread is also blocked when trying to clear more PG_writeback, because
> the client side nr_writeback limit has been reached. In summary,
>
> server blocked => nr_writeback stuck => nr_writeback limit reached
> => bdi-flush blocked => no end_page_writeback() => dirtier blocked
> => nr_dirty stuck
>
> Thanks,
> Fengguang
>
> > > 11045 53987 6490
> > > 11033 53120 8145
> > > 11195 52143 10886
> > > 11211 52144 10913
> > > 11211 52144 10913
> > > 11211 52144 10913
> > >
> > > btrfs seems to maintain a private pool of writeback pages, which can go out of
> > > control:
> > >
> > > nr_writeback nr_dirty
> > > 261075 132
> > > 252891 195
> > > 244795 187
> > > 236851 187
> > > 228830 187
> > > 221040 218
> > > 212674 237
> > > 204981 237
> > >
> > > XFS has very interesting "bumpy writeback" behavior: it tends to wait
> > > collect enough pages and then write the whole world.
> > >
> > > nr_writeback nr_dirty
> > > 80781 0
> > > 37117 37703
> > > 37117 43933
> > > 81044 6
> > > 81050 0
> > > 43943 10199
> > > 43930 36355
> > > 43930 36355
> > > 80293 0
> > > 80285 0
> > > 80285 0
> > >
> > > Thanks,
> > > Fengguang
> > >
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > > the body of a message to majordomo@vger.kernel.org
> > > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > > Please read the FAQ at http://www.tux.org/lkml/
next prev parent reply other threads:[~2009-10-08 5:33 UTC|newest]
Thread overview: 116+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-07 7:38 [PATCH 00/45] some writeback experiments Wu Fengguang
2009-10-07 7:38 ` [PATCH 01/45] writeback: reduce calls to global_page_state in balance_dirty_pages() Wu Fengguang
2009-10-09 15:12 ` Jan Kara
2009-10-09 15:18 ` Peter Zijlstra
2009-10-09 15:47 ` Jan Kara
2009-10-11 2:28 ` Wu Fengguang
2009-10-11 7:44 ` Peter Zijlstra
2009-10-11 10:50 ` Wu Fengguang
2009-10-11 10:58 ` Peter Zijlstra
2009-10-11 11:25 ` Peter Zijlstra
2009-10-12 1:26 ` Wu Fengguang
2009-10-12 9:07 ` Peter Zijlstra
2009-10-12 9:24 ` Wu Fengguang
2009-10-10 21:33 ` Wu Fengguang
2009-10-12 21:18 ` Jan Kara
2009-10-13 3:24 ` Wu Fengguang
2009-10-13 8:41 ` Peter Zijlstra
2009-10-13 18:12 ` Jan Kara
2009-10-13 18:28 ` Peter Zijlstra
2009-10-14 1:38 ` Wu Fengguang
2009-10-14 11:22 ` Peter Zijlstra
2009-10-17 5:30 ` Wu Fengguang
2009-10-07 7:38 ` [PATCH 02/45] writeback: reduce calculation of bdi dirty thresholds Wu Fengguang
2009-10-07 7:38 ` [PATCH 03/45] ext4: remove unused parameter wbc from __ext4_journalled_writepage() Wu Fengguang
2009-10-07 7:38 ` [PATCH 04/45] writeback: remove unused nonblocking and congestion checks Wu Fengguang
2009-10-09 15:26 ` Jan Kara
2009-10-10 13:47 ` Wu Fengguang
2009-10-07 7:38 ` [PATCH 05/45] writeback: remove the always false bdi_cap_writeback_dirty() test Wu Fengguang
2009-10-07 7:38 ` [PATCH 06/45] writeback: use larger ratelimit when dirty_exceeded Wu Fengguang
2009-10-07 8:53 ` Peter Zijlstra
2009-10-07 9:17 ` Wu Fengguang
2009-10-07 7:38 ` [PATCH 07/45] writeback: dont redirty tail an inode with dirty pages Wu Fengguang
2009-10-09 15:45 ` Jan Kara
2009-10-07 7:38 ` [PATCH 08/45] writeback: quit on wrap for .range_cyclic (write_cache_pages) Wu Fengguang
2009-10-07 7:38 ` [PATCH 09/45] writeback: quit on wrap for .range_cyclic (pohmelfs) Wu Fengguang
2009-10-07 12:32 ` Evgeniy Polyakov
2009-10-07 14:23 ` Wu Fengguang
2009-10-07 7:38 ` [PATCH 10/45] writeback: quit on wrap for .range_cyclic (btrfs) Wu Fengguang
2009-10-07 7:38 ` [PATCH 11/45] writeback: quit on wrap for .range_cyclic (cifs) Wu Fengguang
2009-10-07 7:38 ` [PATCH 12/45] writeback: quit on wrap for .range_cyclic (ext4) Wu Fengguang
2009-10-07 7:38 ` [PATCH 13/45] writeback: quit on wrap for .range_cyclic (gfs2) Wu Fengguang
2009-10-07 7:38 ` [PATCH 14/45] writeback: quit on wrap for .range_cyclic (afs) Wu Fengguang
2009-10-07 7:38 ` [PATCH 15/45] writeback: fix queue_io() ordering Wu Fengguang
2009-10-07 7:38 ` [PATCH 16/45] writeback: merge for_kupdate and !for_kupdate cases Wu Fengguang
2009-10-07 7:38 ` [PATCH 17/45] writeback: only allow two background writeback works Wu Fengguang
2009-10-07 7:38 ` [PATCH 18/45] writeback: introduce wait queue for balance_dirty_pages() Wu Fengguang
2009-10-08 1:01 ` KAMEZAWA Hiroyuki
2009-10-08 1:58 ` Wu Fengguang
2009-10-08 2:40 ` KAMEZAWA Hiroyuki
2009-10-08 4:01 ` Wu Fengguang
2009-10-08 5:59 ` KAMEZAWA Hiroyuki
2009-10-08 6:07 ` Wu Fengguang
2009-10-08 6:28 ` Wu Fengguang
2009-10-08 6:39 ` KAMEZAWA Hiroyuki
2009-10-08 8:08 ` Peter Zijlstra
2009-10-08 8:11 ` KAMEZAWA Hiroyuki
2009-10-08 8:36 ` Jens Axboe
2009-10-09 2:52 ` [PATCH] writeback: account IO throttling wait as iowait Wu Fengguang
2009-10-09 10:41 ` Jens Axboe
2009-10-09 10:58 ` Wu Fengguang
2009-10-09 11:01 ` Jens Axboe
2009-10-08 8:05 ` [PATCH 18/45] writeback: introduce wait queue for balance_dirty_pages() Peter Zijlstra
2009-10-07 7:38 ` [PATCH 19/45] writeback: remove the loop in balance_dirty_pages() Wu Fengguang
2009-10-07 7:38 ` [PATCH 20/45] NFS: introduce writeback wait queue Wu Fengguang
2009-10-07 8:53 ` Peter Zijlstra
2009-10-07 9:07 ` Wu Fengguang
2009-10-07 9:15 ` Peter Zijlstra
2009-10-07 9:19 ` Wu Fengguang
2009-10-07 9:17 ` Nick Piggin
2009-10-07 9:52 ` Wu Fengguang
2009-10-07 7:38 ` [PATCH 21/45] writeback: estimate bdi write bandwidth Wu Fengguang
2009-10-07 8:53 ` Peter Zijlstra
2009-10-07 9:39 ` Wu Fengguang
2009-10-07 7:38 ` [PATCH 22/45] writeback: show bdi write bandwidth in debugfs Wu Fengguang
2009-10-07 7:38 ` [PATCH 23/45] writeback: kill space in debugfs item name Wu Fengguang
2009-10-07 7:38 ` [PATCH 24/45] writeback: remove global nr_to_write and use timeout instead Wu Fengguang
2009-10-07 7:38 ` [PATCH 25/45] writeback: convert wbc.nr_to_write to per-file parameter Wu Fengguang
2009-10-07 7:38 ` [PATCH 26/45] block: pass the non-rotational queue flag to backing_dev_info Wu Fengguang
2009-10-07 7:38 ` [PATCH 27/45] writeback: introduce wbc.for_background Wu Fengguang
2009-10-07 7:38 ` [PATCH 28/45] writeback: introduce wbc.nr_segments Wu Fengguang
2009-10-07 7:38 ` [PATCH 29/45] writeback: fix the shmem AOP_WRITEPAGE_ACTIVATE case Wu Fengguang
2009-10-07 11:57 ` Hugh Dickins
2009-10-07 14:00 ` Wu Fengguang
2009-10-07 7:38 ` [PATCH 30/45] vmscan: lumpy pageout Wu Fengguang
2009-10-07 7:38 ` [PATCH 31/45] writeback: sync old inodes first in background writeback Wu Fengguang
2010-07-12 3:01 ` Christoph Hellwig
2010-07-12 15:24 ` Wu Fengguang
2009-10-07 7:38 ` [PATCH 32/45] writeback: update kupdate expire timestamp on each scan of b_io Wu Fengguang
2009-10-07 7:38 ` [PATCH 34/45] writeback: sync livelock - kick background writeback Wu Fengguang
2009-10-07 7:38 ` [PATCH 35/45] writeback: sync livelock - use single timestamp for whole sync work Wu Fengguang
2009-10-07 7:38 ` [PATCH 36/45] writeback: sync livelock - curb dirty speed for inodes to be synced Wu Fengguang
2009-10-07 7:38 ` [PATCH 37/45] writeback: use timestamp to indicate dirty exceeded Wu Fengguang
2009-10-07 7:38 ` [PATCH 38/45] writeback: introduce queue b_more_io_wait Wu Fengguang
2009-10-07 7:38 ` [PATCH 39/45] writeback: remove wbc.more_io Wu Fengguang
2009-10-07 7:38 ` [PATCH 40/45] writeback: requeue_io_wait() on I_SYNC locked inode Wu Fengguang
2009-10-07 7:38 ` [PATCH 41/45] writeback: requeue_io_wait() on pages_skipped inode Wu Fengguang
2009-10-07 7:39 ` [PATCH 42/45] writeback: requeue_io_wait() on blocked inode Wu Fengguang
2009-10-07 7:39 ` [PATCH 43/45] writeback: requeue_io_wait() on fs redirtied inode Wu Fengguang
2009-10-07 7:39 ` [PATCH 44/45] NFS: remove NFS_INO_FLUSHING lock Wu Fengguang
2009-10-07 13:11 ` Peter Staubach
2009-10-07 13:32 ` Wu Fengguang
2009-10-07 13:59 ` Peter Staubach
2009-10-08 1:44 ` Wu Fengguang
2009-10-07 7:39 ` [PATCH 45/45] btrfs: fix race on syncing the btree inode Wu Fengguang
2009-10-07 8:53 ` [PATCH 00/45] some writeback experiments Peter Zijlstra
2009-10-07 10:17 ` [PATCH 14/45] writeback: quit on wrap for .range_cyclic (afs) David Howells
2009-10-07 10:21 ` Nick Piggin
2009-10-07 10:47 ` Wu Fengguang
2009-10-07 11:23 ` Nick Piggin
2009-10-07 12:21 ` Wu Fengguang
2009-10-07 13:47 ` [PATCH 00/45] some writeback experiments Peter Staubach
2009-10-07 15:18 ` Wu Fengguang
2009-10-08 5:33 ` Wu Fengguang [this message]
2009-10-08 5:44 ` Wu Fengguang
2009-10-07 14:26 ` Theodore Tso
2009-10-07 14:45 ` Wu Fengguang
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