From: Andi Kleen <andi@firstfloor.org>
To: Quentin Barnes <qbarnes+nfs@yahoo-inc.com>
Cc: linux-kernel@vger.kernel.org, fengguang.wu@intel.com
Subject: Re: [RFC][PATCH] Disabling read-ahead makes I/O of large reads small
Date: Tue, 29 Dec 2009 19:04:43 +0100 [thread overview]
Message-ID: <87aax18xms.fsf@basil.nowhere.org> (raw)
In-Reply-To: <20091225000717.GA26949@yahoo-inc.com> (Quentin Barnes's message of "Thu, 24 Dec 2009 18:07:17 -0600")
Quentin Barnes <qbarnes+nfs@yahoo-inc.com> writes:
cc fengguang who is Mr.Readahead. The full description+patch
is in the archives.
> In porting some application code to Linux, its performance over
> NFSv3 on Linux is terrible. I'm posting this note to LKML since
> the problem was actually tracked back to the VFS layer.
[...]
> I have no idea if my patch is the appropriate fix. I'm well out of
> my area in this part of the kernel. It solves this one problem, but
> I have no idea how many boundary cases it doesn't cover or even if
> it is the right way to go about addressing this issue.
>
> Is this behavior of shorting I/O of read(2) considered a bug? And
> is this approach for a fix approriate?
It sounds like a (performance) bug to me.
>From a quick look your fix looks reasonable to me.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2009-12-29 18:04 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-25 0:07 [RFC][PATCH] Disabling read-ahead makes I/O of large reads small Quentin Barnes
2009-12-29 18:04 ` Andi Kleen [this message]
2009-12-30 5:15 ` Wu Fengguang
2009-12-30 5:17 ` [RFC][PATCH 1/2] readahead: replace ra->mmap_miss with ra->flags Wu Fengguang
2009-12-30 5:24 ` [RFC][PATCH 2/2] readahead: avoid page-by-page reads on POSIX_FADV_RANDOM Wu Fengguang
2009-12-30 18:02 ` Andi Kleen
2009-12-31 1:39 ` Wu Fengguang
2009-12-31 2:53 ` Wu Fengguang
2009-12-31 3:03 ` Wu Fengguang
2009-12-31 4:31 ` [RFC][PATCH v2] readahead: introduce O_RANDOM_READ for POSIX_FADV_RANDOM Wu Fengguang
2010-01-08 13:08 ` Christoph Hellwig
2010-01-09 13:59 ` Wu Fengguang
2010-01-09 14:01 ` Wu Fengguang
2010-01-04 4:50 ` [RFC][PATCH v3] readahead: introduce O_RANDOM " Wu Fengguang
2010-01-04 5:17 ` Stephen Rothwell
2010-01-04 7:33 ` Christoph Hellwig
2010-01-04 12:56 ` [RFC][PATCH v4] " Wu Fengguang
2010-01-05 2:03 ` Stephen Rothwell
2010-01-05 2:26 ` Wu Fengguang
2010-01-05 2:28 ` Stephen Rothwell
2010-01-05 2:45 ` Wu Fengguang
2010-01-05 5:21 ` Eric Paris
2010-01-05 3:18 ` [RFC][PATCH v5] " Wu Fengguang
2010-01-05 3:27 ` Wu Fengguang
2010-01-04 16:50 ` [RFC][PATCH v3] " Quentin Barnes
2010-01-04 18:57 ` Andreas Dilger
2010-01-04 5:20 ` Minchan Kim
2010-01-04 12:16 ` Wu Fengguang
2010-01-05 1:46 ` Minchan Kim
2010-01-05 2:16 ` Wu Fengguang
2010-01-05 3:40 ` Minchan Kim
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