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From: Arnaldo Carvalho de Melo <acme@redhat.com>
To: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Cc: Chris Snook <csnook@redhat.com>,
	David Miller <davem@davemloft.net>,
	rick.jones2@hp.com, netdev@vger.kernel.org
Subject: Re: RFC: Nagle latency tuning
Date: Tue, 9 Sep 2008 10:00:29 -0300	[thread overview]
Message-ID: <20080909130029.GA12726@ghostprotocols.net> (raw)
In-Reply-To: <20080909062208.GB30385@2ka.mipt.ru>

Em Tue, Sep 09, 2008 at 10:22:08AM +0400, Evgeniy Polyakov escreveu:
> Hi.
> 
> On Tue, Sep 09, 2008 at 01:56:12AM -0400, Chris Snook (csnook@redhat.com) wrote:
> > The easiest way to see the problem is to open a TCP socket to an echo 
> > daemon on loopback, make a bunch of small writes totaling less than your 
> > loopback MTU (accounting for overhead), and see how long it takes to get 
> > your echoes.  You can probably do this with netcat, though I haven't 
> > tried.  People don't expect loopback to have 40 ms latency when the box 
> > is lightly loaded, so they'd really like to tweak that down when it's 
> > hurting them.
> 
> Isn't Nagle without corking a very bad idea? Or you can not change the
> application?

In one such case, finantial app building logical packets via several
small buffer send calls I got it working with a "autocorking" LD_PRELOAD
library, libautocork:

http://git.kernel.org/?p=linux/kernel/git/acme/libautocork.git

git://git.kernel.org/pub/scm/linux/kernel/git/acme/libautocork.git

Details/test cases:

http://git.kernel.org/?p=linux/kernel/git/acme/libautocork.git;a=blob_plain;f=tcp_nodelay.txt

How to use it, what you get from using it:

http://git.kernel.org/?p=linux/kernel/git/acme/libautocork.git;a=blob_plain;f=libautocork.txt

- Arnaldo

  parent reply	other threads:[~2008-09-09 13:10 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-09-08 21:56 RFC: Nagle latency tuning Christopher Snook
2008-09-08 22:39 ` Rick Jones
2008-09-09  5:10   ` Chris Snook
2008-09-09  5:17     ` David Miller
2008-09-09  5:56       ` Chris Snook
2008-09-09  6:02         ` David Miller
2008-09-09 10:31           ` Mark Brown
2008-09-09 12:05             ` David Miller
2008-09-09 12:09               ` Mark Brown
2008-09-09 12:19                 ` David Miller
2008-09-09  6:22         ` Evgeniy Polyakov
2008-09-09  6:28           ` Chris Snook
2008-09-09 13:00           ` Arnaldo Carvalho de Melo [this message]
2008-09-09 14:36     ` Andi Kleen
2008-09-09 18:40       ` Chris Snook
2008-09-09 19:07         ` Andi Kleen
2008-09-09 19:21           ` Arnaldo Carvalho de Melo
2008-09-11  4:08           ` Chris Snook
2008-09-09 19:59         ` David Miller
2008-09-09 20:25           ` Chris Snook
2008-09-22 10:49           ` David Miller
2008-09-22 11:09             ` David Miller
2008-09-22 20:30               ` Andi Kleen
2008-09-22 22:22                 ` Chris Snook
2008-09-22 22:26                   ` David Miller
2008-09-22 23:00                     ` Chris Snook
2008-09-22 23:13                       ` David Miller
2008-09-22 23:24                         ` Andi Kleen
2008-09-22 23:21                           ` David Miller
2008-09-23  0:14                             ` Andi Kleen
2008-09-23  0:33                               ` Rick Jones
2008-09-23  2:12                                 ` Andi Kleen
2008-09-23  1:40                               ` David Miller
2008-09-23  2:23                                 ` Andi Kleen
2008-09-23  2:28                                   ` David Miller
2008-09-23  2:41                                     ` Andi Kleen
2008-09-22 22:47                   ` Rick Jones
2008-09-22 22:57                     ` Chris Snook
2008-09-09 16:33     ` Rick Jones
2008-09-09 16:54       ` Chuck Lever
2008-09-09 17:21         ` Arnaldo Carvalho de Melo
2008-09-09 17:54         ` Rick Jones
2008-09-08 22:55 ` Andi Kleen
2008-09-09  5:22   ` Chris Snook

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