From: Christoph Hellwig <hch@lst.de>
To: Avi Kivity <avi@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, Chris Webb <chris@arachsys.com>,
balbir@linux.vnet.ibm.com,
KVM development list <kvm@vger.kernel.org>,
Rik van Riel <riel@surriel.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Kevin Wolf <kwolf@redhat.com>
Subject: Re: [PATCH][RF C/T/D] Unmapped page cache control - via boot parameter
Date: Wed, 17 Mar 2010 09:49:11 +0100 [thread overview]
Message-ID: <20100317084911.GA9098@lst.de> (raw)
In-Reply-To: <4B9F66AC.5080400@redhat.com>
On Tue, Mar 16, 2010 at 01:08:28PM +0200, Avi Kivity wrote:
> If the batch size is larger than the virtio queue size, or if there are
> no flushes at all, then yes the huge write cache gives more opportunity
> for reordering. But we're already talking hundreds of requests here.
Yes. And rememember those don't have to come from the same host. Also
remember that we rather limit execssive reodering of O_DIRECT requests
in the I/O scheduler because they are "synchronous" type I/O while
we don't do that for pagecache writeback.
And we don't have unlimited virtio queue size, in fact it's quite
limited.
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next prev parent reply other threads:[~2010-03-17 8:49 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-15 7:22 [PATCH][RF C/T/D] Unmapped page cache control - via boot parameter Balbir Singh
2010-03-15 7:48 ` Avi Kivity
2010-03-15 8:07 ` Balbir Singh
2010-03-15 8:27 ` Avi Kivity
2010-03-15 9:17 ` Balbir Singh
2010-03-15 9:27 ` Avi Kivity
2010-03-15 10:45 ` Balbir Singh
2010-03-15 18:48 ` Anthony Liguori
2010-03-16 9:05 ` Avi Kivity
2010-03-19 7:23 ` Dave Hansen
2010-03-15 20:23 ` Chris Webb
2010-03-15 23:43 ` Anthony Liguori
2010-03-16 0:43 ` Christoph Hellwig
2010-03-16 1:27 ` Anthony Liguori
2010-03-16 8:19 ` Christoph Hellwig
2010-03-17 15:14 ` Chris Webb
2010-03-17 15:55 ` Anthony Liguori
2010-03-17 16:27 ` Chris Webb
2010-03-22 21:04 ` Chris Webb
2010-03-22 21:07 ` Avi Kivity
2010-03-22 21:10 ` Chris Webb
2010-03-17 16:27 ` Balbir Singh
2010-03-17 17:05 ` Vivek Goyal
2010-03-17 19:11 ` Chris Webb
2010-03-16 3:16 ` Balbir Singh
2010-03-16 9:17 ` Avi Kivity
2010-03-16 9:54 ` Kevin Wolf
2010-03-16 10:16 ` Avi Kivity
2010-03-16 10:26 ` Christoph Hellwig
2010-03-16 10:36 ` Avi Kivity
2010-03-16 10:44 ` Christoph Hellwig
2010-03-16 11:08 ` Avi Kivity
2010-03-16 14:27 ` Balbir Singh
2010-03-16 15:59 ` Avi Kivity
2010-03-17 8:49 ` Christoph Hellwig [this message]
2010-03-17 9:10 ` Avi Kivity
2010-03-17 15:24 ` Chris Webb
2010-03-17 16:22 ` Avi Kivity
2010-03-17 16:40 ` Avi Kivity
2010-03-17 16:47 ` Chris Webb
2010-03-17 16:53 ` Avi Kivity
2010-03-17 16:58 ` Christoph Hellwig
2010-03-17 17:03 ` Avi Kivity
2010-03-17 16:57 ` Christoph Hellwig
2010-03-17 17:06 ` Avi Kivity
2010-03-17 16:52 ` Christoph Hellwig
2010-03-17 17:02 ` Avi Kivity
2010-03-15 15:46 ` Randy Dunlap
2010-03-16 3:21 ` Balbir Singh
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