From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965252AbXATKYD (ORCPT ); Sat, 20 Jan 2007 05:24:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965251AbXATKYD (ORCPT ); Sat, 20 Jan 2007 05:24:03 -0500 Received: from wx-out-0506.google.com ([66.249.82.225]:11377 "EHLO wx-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965246AbXATKYB (ORCPT ); Sat, 20 Jan 2007 05:24:01 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition; b=KSzVUB+iUh5tddLPjtmkkxjD/wm9zq2ntAgWfcvmhj740FcpfdaWrueEOpthjvlEg8dCfqbae6K0/CxXJxEYX0TwpCtNTANkcpD/nu4q2XCjgjBhLXwOKfKBDfHKMNL+x3Kd3Zb9nYWe17ZY3w617OzrxQJ8OSKCU5h6bKpPRaE= Message-ID: Date: Sat, 20 Jan 2007 15:54:00 +0530 From: "kalash nainwal" To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: wake_up() takes long time to return MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi there, We've a kernel (n/w) module, which sits over ethernet. Whenever a pkt is received (in softirq), after doing some minimal processing, wake_up() is called to wake up another kernel thread which does rest (bulk) of the processing. We notice that this wake_up() call is sometimes taking as long as 48 milli-seconds to return. This happens around 10 times out of 10M. We earlier thought its possibly because of the contention on rq->lock, but we see the same phenomenon even on a uniprocessor box. So obviosly thats not the case. We can't figure out any other reason for wake_up() to take this much time? As this call comes directly in our (receive) hotpath, we're very concerned. Any help would be greatly appreciated. Thanks and regards, -Kalash