Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750952AbWJMXPr (ORCPT ); Fri, 13 Oct 2006 19:15:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751224AbWJMXPr (ORCPT ); Fri, 13 Oct 2006 19:15:47 -0400 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:34967 "EHLO lxorguk.ukuu.org.uk") by vger.kernel.org with ESMTP id S1750952AbWJMXPq (ORCPT ); Fri, 13 Oct 2006 19:15:46 -0400 Subject: Re: [linux-usb-devel] USB performance bug since kernel 2.6.13 (CRITICAL???) From: Alan Cox To: Open Source Cc: Alan Stern , linux-usb-devel@lists.sourceforge.net, =?ISO-8859-1?Q?WolfgangM=FCes?= , linux-kernel@vger.kernel.org In-Reply-To: <20061013230240.84447.qmail@web58108.mail.re3.yahoo.com> References: <20061013230240.84447.qmail@web58108.mail.re3.yahoo.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Sat, 14 Oct 2006 00:41:44 +0100 Message-Id: <1160782904.25218.93.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.2 (2.6.2-1.fc5.5) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 873 Lines: 20 Ar Gwe, 2006-10-13 am 16:02 -0700, ysgrifennodd Open Source: > clear understanding of what is causing it. As it stands it doesn't > seem like even the experts know exactly where this > delay is being caused. strace should tell you precisely how long each syscall takes if you ask it to trace things nicely. If you have code trying to wait for a tiny time then HZ will bump the wait to be longer (kernel or user) but for other cases all should be fine either way. The other issues like priority and paging caused delays can generally be dealt with by having the relevant service code running mlockall and real time priority. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/