On Thu, 2 Oct 2008 21:23:55 -0700 Arjan van de Ven <arjan@infradead.org> wrote:
quoted text > On Thu, 2 Oct 2008 21:01:17 -0700
> Arjan van de Ven <arjan@infradead.org> wrote:
>
> > > _
> > >
> > > perhaps for varying values of "1".
> >
>
> caught a few, a few were over 3 1/2 seconds in stall time
> (specifically I know this for the last one)
>
> (I've stripped out the ? entries to keep them reasonable)
>
> [ 410.168277] WARNING: at kernel/sched.c:5652 io_schedule+0x77/0xb0()
> [ 410.168347] Pid: 699, comm: kjournald Not tainted 2.6.27-rc8-tip #50
> [ 410.168366] [<c042ee64>] warn_on_slowpath+0x41/0x65
> [ 410.168414] [<c070ec83>] io_schedule+0x77/0xb0
> [ 410.168421] [<c04abc72>] sync_buffer+0x33/0x37
> [ 410.168429] [<c070f123>] __wait_on_bit+0x36/0x5d
> [ 410.168445] [<c070f1f5>] out_of_line_wait_on_bit+0xab/0xb3
> [ 410.168471] [<c04abbd1>] __wait_on_buffer+0x19/0x1c
> [ 410.168478] [<c04de796>] journal_commit_transaction+0x484/0xcb2
> [ 410.168519] [<c04e14ae>] kjournald+0xc7/0x1ea
> [ 410.168544] [<c043fb87>] kthread+0x3b/0x61
> [ 410.168559] [<c040499f>] kernel_thread_helper+0x7/0x10
> [ 410.168567] =======================
> [ 410.168572] ---[ end trace de523043f88bd9a7 ]---
> [ 451.605034] ------------[ cut here ]------------
> [ 451.605041] WARNING: at kernel/sched.c:5652 io_schedule+0x77/0xb0()
> [ 451.605114] Pid: 699, comm: kjournald Tainted: G W 2.6.27-rc8-tip #50
>
> ...
>
hm, they're all kjournald getting stuck on lock_buffer(). That _may_
be related to the one we care about, but it doesn't seem likely.
quoted text > [ 517.067556] Pid: 4320, comm: claws-mail Tainted: G W 2.6.27-rc8-tip #50
> [ 517.067572] [<c042ee64>] warn_on_slowpath+0x41/0x65
> [ 517.067652] [<c070ec83>] io_schedule+0x77/0xb0
> [ 517.067659] [<c04abc72>] sync_buffer+0x33/0x37
> [ 517.067666] [<c070f010>] __wait_on_bit_lock+0x34/0x5e
> [ 517.067682] [<c070f0e5>] out_of_line_wait_on_bit_lock+0xab/0xb3
> [ 517.067707] [<c04abfa1>] __lock_buffer+0x24/0x2a
> [ 517.067715] [<c04dd7fc>] do_get_write_access+0x64/0x3b1
> [ 517.067743] [<c04ddb64>] journal_get_write_access+0x1b/0x2a
> [ 517.067752] [<c04da374>] __ext3_journal_get_write_access+0x19/0x3c
> [ 517.067761] [<c04cf672>] ext3_reserve_inode_write+0x34/0x68
> [ 517.067769] [<c04cf6d5>] ext3_mark_inode_dirty+0x2f/0x46
> [ 517.067777] [<c04cf7f7>] ext3_dirty_inode+0x53/0x67
> [ 517.067784] [<c04a7bed>] __mark_inode_dirty+0x29/0x144
> [ 517.067794] [<c049e60f>] file_update_time+0x80/0xa9
> [ 517.067803] [<c046b66c>] __generic_file_aio_write_nolock+0x2f0/0x41b
> [ 517.067842] [<c046bf0d>] generic_file_aio_write+0x5a/0xb7
> [ 517.067850] [<c04cdc65>] ext3_file_write+0x1a/0x89
> [ 517.067858] [<c048da41>] do_sync_write+0xab/0xe9
> [ 517.067896] [<c048e302>] vfs_write+0x8a/0x12e
> [ 517.067903] [<c048e43f>] sys_write+0x3b/0x60
> [ 517.067910] [<c0403b0b>] sysenter_do_call+0x12/0x2f
> [ 517.067919] =======================
> [ 517.067923] ---[ end trace de523043f88bd9a7 ]---
That's the one - the lock_buffer() in do_get_write_access(). It's a
major contention site and it'd be a major win if we could fix it. Even
if we resorted to some nasty thing like taking a temp copy of the
buffer's contents.
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Re: [PATCH] Give kjournald a IOPRIO_CLASS_RT io priority , Andrew Morton , (Thu Oct 2, 9:40 pm)
