From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760023AbYEXA4o (ORCPT ); Fri, 23 May 2008 20:56:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753238AbYEXA4h (ORCPT ); Fri, 23 May 2008 20:56:37 -0400 Received: from mx1.redhat.com ([66.187.233.31]:37238 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753003AbYEXA4h (ORCPT ); Fri, 23 May 2008 20:56:37 -0400 Date: Fri, 23 May 2008 20:56:30 -0400 From: Rik van Riel To: "Fausto Richetti Blanco" Cc: linux-kernel@vger.kernel.org Subject: Re: Pipe buffers' limit of 16 * 4K Message-ID: <20080523205630.444fe2b9@bree.surriel.com> In-Reply-To: References: Organization: Red Hat, Inc. X-Mailer: Claws Mail 3.0.2 (GTK+ 2.10.4; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 23 May 2008 21:19:13 -0300 "Fausto Richetti Blanco" wrote: > Hello guys, > > I'm working with a 2.6.9 kernel (ok, I know it's quite old) and > faced a problem with the 4K (one page) buffer limit for the pipes. > I've found that in the 2.6.11 the pipes' buffers were changed to a > circular list of pages which increased this limit to 16 * 4K. This > limit is hardcoded here /usr/src/linux/include/linux/pipe_fs_i.h:6 > #define PIPE_BUFFERS (16) > > Is there a reason for this not to be an adjustable parameter > (eg.: by an ulimit in the userspace) ? What is the problem you found? Why do you need to change the limit from 16? Did it bring you any performance enhancements? If so, how much? -- All rights reversed.