From: "Jon Smirl" <jonsmirl@gmail.com>
To: "Wu Fengguang" <wfg@mail.ustc.edu.cn>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 00/23] Adaptive read-ahead V11
Date: Sat, 18 Mar 2006 23:10:33 -0500 [thread overview]
Message-ID: <9e4733910603182010p394c3233p81825b093fb693c@mail.gmail.com> (raw)
In-Reply-To: <20060319034750.GA8732@mail.ustc.edu.cn>
On 3/18/06, Wu Fengguang <wfg@mail.ustc.edu.cn> wrote:
> On Sat, Mar 18, 2006 at 10:10:43PM -0500, Jon Smirl wrote:
> > This is probably a readahead problem. The lighttpd people that are
> > encountering this problem are not regular lkml readers.
> >
> > http://bugzilla.kernel.org/show_bug.cgi?id=5949
>
> [QUOTE]
> My general conclusion is that since they were able to write a user
> space implementation that avoids the problem something must be broken
> in the kernel readahead logic for sendfile().
>
> Maybe the user space solution does the trick by using a larger window size?
>
> IMHO, the stock read-ahead is not designed with extremely high concurrency in
> mind. However, 100 streams should not be a problem at all.
Has anyone checked to see if the readahead logic is working as
expected from sendfile? IO from sendfile is a different type of
context than IO from user space, there could be sendfile specific
problems. If window size is the trick, shouldn't sendfile
automatically adapt it's window size? I don't think you can control
the sendfile window size from user space.
The goal of sendfile is to be the most optimal way to send a file over
the network. This is a case where user space code is easily beating
it.
--
Jon Smirl
jonsmirl@gmail.com
next prev parent reply other threads:[~2006-03-19 4:10 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-19 2:34 Wu Fengguang
2006-03-19 2:34 ` [PATCH 01/23] readahead: kconfig options Wu Fengguang
2006-03-19 2:34 ` [PATCH 02/23] radixtree: look-aside cache Wu Fengguang
2006-03-20 16:01 ` Christoph Lameter
2006-03-21 2:19 ` Wu Fengguang
2006-03-19 2:34 ` [PATCH 03/23] radixtree: hole scanning functions Wu Fengguang
2006-03-19 2:34 ` [PATCH 04/23] readahead: page flag PG_readahead Wu Fengguang
2006-03-19 2:34 ` [PATCH 05/23] readahead: refactor do_generic_mapping_read() Wu Fengguang
2006-03-19 2:34 ` [PATCH 06/23] readahead: refactor __do_page_cache_readahead() Wu Fengguang
2006-03-19 2:34 ` [PATCH 07/23] readahead: insert cond_resched() calls Wu Fengguang
2006-03-19 3:50 ` Lee Revell
2006-03-19 5:32 ` Wu Fengguang
2006-03-20 13:31 ` Wu Fengguang
2006-03-19 2:34 ` [PATCH 08/23] readahead: common macros Wu Fengguang
2006-03-19 2:34 ` [PATCH 09/23] readahead: events accounting Wu Fengguang
2006-03-19 2:34 ` [PATCH 10/23] readahead: support functions Wu Fengguang
2006-03-19 2:34 ` [PATCH 11/23] readahead: sysctl parameters Wu Fengguang
2006-03-19 2:34 ` [PATCH 12/23] readahead: min/max sizes Wu Fengguang
2006-03-19 2:34 ` [PATCH 13/23] readahead: page cache aging accounting Wu Fengguang
2006-03-19 2:34 ` [PATCH 14/23] readahead: state based method Wu Fengguang
2006-03-19 2:34 ` [PATCH 15/23] readahead: context " Wu Fengguang
2006-03-19 2:34 ` [PATCH 16/23] readahead: other methods Wu Fengguang
2006-03-19 2:34 ` [PATCH 17/23] readahead: call scheme Wu Fengguang
2006-03-19 2:34 ` [PATCH 18/23] readahead: laptop mode Wu Fengguang
2006-03-19 2:34 ` [PATCH 19/23] readahead: loop case Wu Fengguang
2006-03-19 2:34 ` [PATCH 20/23] readahead: nfsd case Wu Fengguang
2006-03-19 2:34 ` [PATCH 21/23] readahead: debug radix tree new functions Wu Fengguang
2006-03-19 2:34 ` [PATCH 22/23] readahead: debug traces showing accessed file names Wu Fengguang
2006-03-19 2:34 ` [PATCH 23/23] readahead: debug traces showing read patterns Wu Fengguang
2006-03-19 3:10 ` [PATCH 00/23] Adaptive read-ahead V11 Jon Smirl
2006-03-19 3:47 ` Wu Fengguang
2006-03-19 4:10 ` Jon Smirl [this message]
2006-03-19 5:09 ` Wu Fengguang
2006-03-19 15:53 ` Jon Smirl
2006-03-20 13:54 ` Wu Fengguang
2006-03-27 21:38 ` Matt Heler
2006-03-28 3:44 ` Wu Fengguang
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