Message-ID: <4CF12BAB.3000704@kernel.org>
Date: Sat, 27 Nov 2010 17:02:51 +0100
From: Tejun Heo <tj@kernel.org>
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To: Jens Axboe <jaxboe@fusionio.com>
CC: Christoph Hellwig <hch@lst.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCHSET] backing-dev: replace private thread pool with  workqueue
References: <1283777182-11426-1-git-send-email-tj@kernel.org> <20100907121608.GA26597@lst.de> <4C862DDC.6010702@kernel.org> <4C86303A.90601@fusionio.com> <4C8631BE.9030709@kernel.org>
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On 09/07/2010 02:36 PM, Tejun Heo wrote:
> Hello,
> 
> On 09/07/2010 02:29 PM, Jens Axboe wrote:
>> I agree (with both of you). It's definitely too early to convert it
>> over, but if we can in the longer run, it never hurts to get rid of
>> code. The writeback threads aren't a typical threadpool, in that the
>> threads stick around and only go away when idle for too long. If they
>> stick around, you get the same process hammering IO at your device. So
>> converting that over to the generic cwq may or may not be at a
>> performance cost, it'll definitely have to be tested.
> 
> One thing to try is removing WQ_UNBOUND and see how it affects the
> performance.  I put WQ_UNBOUND there mainly to keep the behavior about
> the same as the current code but given what it does I think it would
> probably fare better with workers bound to CPUs.

cmwq now seems pretty solid.  There hasn't been any noticeable failure
yet.  I think we can move on with this conversion now.  Shall I
refresh the patchset against the current block tree?

Thanks.

-- 
tejun
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