Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751299AbVJQN3A (ORCPT ); Mon, 17 Oct 2005 09:29:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751320AbVJQN3A (ORCPT ); Mon, 17 Oct 2005 09:29:00 -0400 Received: from gw1.cosmosbay.com ([62.23.185.226]:10723 "EHLO gw1.cosmosbay.com") by vger.kernel.org with ESMTP id S1751299AbVJQN27 (ORCPT ); Mon, 17 Oct 2005 09:28:59 -0400 Message-ID: <4353A6F6.9050205@cosmosbay.com> Date: Mon, 17 Oct 2005 15:28:22 +0200 From: Eric Dumazet User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) X-Accept-Language: fr, en MIME-Version: 1.0 To: dipankar@in.ibm.com CC: Jean Delvare , torvalds@osdl.org, Serge Belyshev , LKML , Andrew Morton , Manfred Spraul Subject: Re: [RCU problem] was VFS: file-max limit 50044 reached References: <20051017084609.GA6257@in.ibm.com> <43536A6C.102@cosmosbay.com> <20051017103244.GB6257@in.ibm.com> <435394A1.7000109@cosmosbay.com> <20051017123655.GD6257@in.ibm.com> In-Reply-To: <20051017123655.GD6257@in.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-1.6 (gw1.cosmosbay.com [172.16.8.80]); Mon, 17 Oct 2005 15:28:23 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1632 Lines: 46 Dipankar Sarma a ?crit : > On Mon, Oct 17, 2005 at 02:10:09PM +0200, Eric Dumazet wrote: > >>Dipankar Sarma a ?crit : >> >>>On Mon, Oct 17, 2005 at 11:10:04AM +0200, Eric Dumazet wrote: >>> >>>Agreed. It is not designed to work that way, so there must be >>>a bug somewhere and I am trying to track it down. It could very well >>>be that at maxbatch=10 we are just queueing at a rate far too high >>>compared to processing. >>> >> >>I can freeze my test machine with a program that 'only' use dentries, no >>files. >> >>No message, no panic, but machine becomes totally unresponsive after few >>seconds. >> >>Just greping for call_rcu in kernel sources gave me another call_rcu() use >>from syscalls. And yes 2.6.13 has the same problem. > > > Can you try it with rcupdate.maxbatch set to 10000 in boot > command line ? > Changing maxbatch from 10 to 10000 cures the problem. Maybe we could initialize maxbatch to (10000000/HZ), considering no current cpu is able to queue more than 10.000.000 items per second in a list. > FWIW, the open/close test problem goes away if I set maxbatch to > 10000. I had introduced this limit some time ago to curtail > the effect long running softirq handlers have on scheduling > latencies, which now conflicts with OOM avoidance requirements. Yes, and probably OOM avoidance has a higher priority than latencies in DOS situations... Eric - 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/