Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752007AbWJMX6V (ORCPT ); Fri, 13 Oct 2006 19:58:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752006AbWJMX6V (ORCPT ); Fri, 13 Oct 2006 19:58:21 -0400 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:53661 "EHLO lxorguk.ukuu.org.uk") by vger.kernel.org with ESMTP id S1752007AbWJMX6U (ORCPT ); Fri, 13 Oct 2006 19:58:20 -0400 Subject: Re: USB performance bug since kernel 2.6.13 (CRITICAL???) From: Alan Cox To: Open Source Cc: linux-usb-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org In-Reply-To: <20061013233024.5786.qmail@web58107.mail.re3.yahoo.com> References: <20061013233024.5786.qmail@web58107.mail.re3.yahoo.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Sat, 14 Oct 2006 01:24:52 +0100 Message-Id: <1160785492.25218.96.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: 772 Lines: 19 Ar Gwe, 2006-10-13 am 16:30 -0700, ysgrifennodd Open Source: > There is an ioctl that is waiting for the URB to be reaped. > I am almost certain it is this syscall that is taking 4 ms (as > opposed to 1 ms with CONFIG_HZ=1000). What does strace say about it ? This is measurable not speculation. > Will the first piece of code wake up immediately or only after the > next HZ timeslice? If it is the latter, which is what I am starting to It depends if there are other things running and on their priority relative to you. - 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/