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Message-Id: <20090623191803.2230.A69D9226@jp.fujitsu.com>
Date: Tue, 23 Jun 2009 19:28:13 +0900 (JST)
From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To: Jens Axboe <jens.axboe@...cle.com>
Cc: kosaki.motohiro@...fujitsu.com,
Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Linux Kernel <linux-kernel@...r.kernel.org>, hch@...radead.org
Subject: Re: merging the per-bdi writeback patchset
Hi
> On Tue, Jun 23 2009, Andrew Morton wrote:
> > On Tue, 23 Jun 2009 10:11:56 +0200 Jens Axboe <jens.axboe@...cle.com> wrote:
> >
> > > Things are looking good for this patchset and it's been in -next for
> > > almost a week without any reports of problems. So I'd like to merge it
> > > for 2.6.31 if at all possible. Any objections?
> >
> > erk. I was rather expecting I'd have time to have a look at it all.
>
> OK, we can wait if we have to, just trying to avoid having to keep this
> fresh for one full cycle. I have posted this patchset 11 times though
> over months, so it's not like it's a new piece of work :-)
>
> > It's unclear to me actually _why_ the performance changes which were
> > observed have actually occurred. In fact it's a bit unclear (to me)
> > why the patchset was written and what it sets out to achieve :(
>
> It started out trying to get rid of the pdflush uneven writeout. If you
> look at various pdflush intensive workloads, even on a single disk you
> often have 5 or more pdflush threads working the same device. It's just
> not optimal. Another issue was starvation with request allocation. Given
> that pdflush does non-blocking writes (it has to, by design), pdflush
> can potentially be starved if someone else is working the device.
Can you please make reproduce program and post mesurement result?
I hope to mesure the same program on my box.
Plus, Can you please write more vervose patch description? your patch is a
bit harder review.
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