From: Kent Overstreet <kmo@daterainc.com>
To: Stefan Priebe - Profihost AG <s.priebe@profihost.ag>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org
Subject: Re: bcache: Fix a writeback performance regression
Date: Wed, 21 Aug 2013 16:47:15 -0700 [thread overview]
Message-ID: <20130821234715.GA4630@moria.home.lan> (raw)
In-Reply-To: <521323D1.1070503@profihost.ag>
On Tue, Aug 20, 2013 at 10:07:45AM +0200, Stefan Priebe - Profihost AG wrote:
> Am 20.08.2013 10:01, schrieb Stefan Priebe - Profihost AG:
> > Am 20.08.2013 00:27, schrieb Kent Overstreet:
> >> On Mon, Aug 19, 2013 at 12:09:24AM +0200, Stefan Priebe wrote:
> >>>
> >>> Vanilla 3.10.7 + bcache: Fix a writeback performance regression
> >>>
> >>> http://pastebin.com/raw.php?i=LXZk4cMH
> >>
> >> Whoops, at first I thought this was the same bug as one I'd already been
> >> chasing down that had been a harmless bug - turns out I didn't look
> >> closely enough at the backtrace.
> >>
> >> What happened is background writeback is deadlocking, because for some
> >> reason the workqueue it's running out of is a singlethreaded workqueue,
> >> so as soon as it decides to queue enough writeback bios that it has to
> >> sleep on that semaphore (which often won't happen due to the PD
> >> controller based ratelimiting) - boom, deadlock.
> >>
> >> Here's the fixup patch I just tested and am applying:
>
> Oh i'm now seeing very high CPU spikes of kworker... i don't see if i
> remove bcache: Fix a writeback performance regression.
Are you able to reproduce it? I'm not having any luck reproducing it...
next prev parent reply other threads:[~2013-08-21 23:47 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-14 22:59 [GIT PULL] bcache fixes for 3.11 Kent Overstreet
2013-08-15 6:43 ` Stefan Priebe - Profihost AG
2013-08-15 7:07 ` Kent Overstreet
2013-08-16 10:11 ` Stefan Priebe - Profihost AG
2013-08-18 22:09 ` bcache: Fix a writeback performance regression Stefan Priebe
2013-08-19 22:27 ` Kent Overstreet
2013-08-20 8:01 ` Stefan Priebe - Profihost AG
2013-08-20 8:07 ` Stefan Priebe - Profihost AG
2013-08-21 21:10 ` Kent Overstreet
2013-08-21 23:47 ` Kent Overstreet [this message]
2013-08-22 5:25 ` Stefan Priebe
2013-08-22 5:27 ` Stefan Priebe
2013-08-22 5:43 ` Kent Overstreet
2013-08-22 5:59 ` Stefan Priebe
2013-08-22 6:02 ` Kent Overstreet
2013-08-22 7:32 ` Stefan Priebe - Profihost AG
2013-08-22 7:42 ` Kent Overstreet
2013-08-26 19:21 ` Stefan Priebe
2013-08-28 3:37 ` kernel neophyte
2013-08-28 6:05 ` Kent Overstreet
2013-08-28 18:12 ` kernel neophyte
2013-08-28 18:38 ` Stefan Priebe - Profihost AG
2013-08-28 18:47 ` kernel neophyte
2013-08-28 19:20 ` Stefan Priebe
2013-08-28 20:12 ` kernel neophyte
2013-08-28 20:15 ` Stefan Priebe
2013-08-28 22:45 ` kernel neophyte
2013-08-29 18:52 ` Stefan Priebe
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