From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755664AbZEVJjm (ORCPT ); Fri, 22 May 2009 05:39:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751729AbZEVJjc (ORCPT ); Fri, 22 May 2009 05:39:32 -0400 Received: from mail-fx0-f158.google.com ([209.85.220.158]:38780 "EHLO mail-fx0-f158.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751063AbZEVJjb (ORCPT ); Fri, 22 May 2009 05:39:31 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:reply-to:date:message-id:subject:from:to:content-type :content-transfer-encoding; b=ZBvyW0wcOZ27zKSeUCUCpQJhk0BCMJ/7MLQILYpkGkFp4LGD2BI3WGKl/m55C5zt4G Co4lNjoHdYkGV/21EUe6yykFHALgLzePhF+37O4/aK/MWVfLKdiav9SthB1PEVUL/P7A hyj//6H+bvueOSL0FBdjrOOuSUP18758xJ+E8= MIME-Version: 1.0 Reply-To: AdvandenBroek.nl@gmail.com Date: Fri, 22 May 2009 11:39:31 +0200 Message-ID: <9f924d250905220239k1dc36aaeib3c2ec955267038a@mail.gmail.com> Subject: PIPE_SIZE aspects From: Ad van den Broek To: linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I searched the net regarding PIPE_SIZE aspects. This is what I found: * The constant PIPE_SIZE establishes the number of bytes allocated for a pipe (the size of the pipe buffer) * The default of PIPE_SIZE (in Linux 2.4) is PAGE_SIZE. * The default of PIPE_SIZE (in Linux 2.6) is 64K. * PAGE_SIZE (in Linux 2.4) is CPU/hw depending, may not be changed and is 4K for x86. * PAGE_SIZE (in Linux 2.6) is 64K. * PIPE_SIZE can be changed in Linux 2.4, but it should be NOT larger than PAGE_SIZE or a patch should be implemented I found a patch (I believe the author is Julian Bradfield) at http://lse.sourceforge.net/pipe/2.4.9-pipe.patch and this patch is modified by Manfred Spraul which version can be found at http://linuxperf.sourceforge.net/patches/2.4.13-largepipe.patch It is tested with PIPE_SIZE from 1 upto 2,4,8 pages. and the result is at http://lse.sourceforge.net/pipe/pipe-report.txt My questions: Is the above info correct ? Is the large pipe patch still correct for last 2.4.x versions ? Is such a patch also required/possible in Linux 2.6 to allow PIPE_SIZE > PAGE_SIZE or is that different in 2.6 ? -- With best regards, Ad van den Broek The Netherlands