From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750994AbXAVJ0P (ORCPT ); Mon, 22 Jan 2007 04:26:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751087AbXAVJ0P (ORCPT ); Mon, 22 Jan 2007 04:26:15 -0500 Received: from wx-out-0506.google.com ([66.249.82.236]:37912 "EHLO wx-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750994AbXAVJ0O (ORCPT ); Mon, 22 Jan 2007 04:26:14 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=gx/LYgSRgjrLqqTOqYP7vskv5jS9jGQCMPAbbE3MyZPMIV/zV3sxAMwh+c2p4PxXv07AuFWEmwUJYXFEa/RKhGxBrogmz/jVWlfa6iQbIeb19gKOK2+heDhuOznzJOliTU/cxnvz2AkMLY2RJp2uwfy/CqIJFW/9syq4A3npghA= Message-ID: Date: Mon, 22 Jan 2007 14:56:13 +0530 From: "kalash nainwal" To: "Arjan van de Ven" Subject: Re: wake_up() takes long time to return Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <1169304446.3055.764.camel@laptopd505.fenrus.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <1169304446.3055.764.camel@laptopd505.fenrus.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 1/20/07, Arjan van de Ven wrote: > On Sat, 2007-01-20 at 15:54 +0530, kalash nainwal wrote: > > 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. > > > Hi, > > unfortunately you didn't provide your driver code or a link to it, so > people who want to help you would have to guess in the dark... could you > reply to this email with the pointer to the code? > > Greetings, > Arjan van de Ven > -- > if you want to mail me at work (you don't), use arjan (at) linux.intel.com > Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org > > Hi Arjan, I won't pretend I'm working on an open-source driver. I personally would be more than happy to share the driver code, but doing so would probably cost me my job :) and so...I won't expect anyone to help me with my code either. Just wanted to know if wake_up is known to take this long to return? (some known linux quirk may be?) If so then under what conditions? or it _definitely_ would be my code only that's screwing up? I'm using do_gettimeofday() before and after wake_up() to measure this time. Thanks and regards, -Kalash