Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759925AbZAWRJB (ORCPT ); Fri, 23 Jan 2009 12:09:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755299AbZAWRIy (ORCPT ); Fri, 23 Jan 2009 12:08:54 -0500 Received: from mx2.suse.de ([195.135.220.15]:51777 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754388AbZAWRIx (ORCPT ); Fri, 23 Jan 2009 12:08:53 -0500 Date: Fri, 23 Jan 2009 09:06:31 -0800 From: Greg KH To: Bron Gondwana Cc: Linux Kernel Mailing List , stable@kernel.org, Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber Subject: Re: [patch 016/104] epoll: introduce resource usage limits Message-ID: <20090123170631.GB11566@suse.de> References: <20081203193901.715896543@mini.kroah.org> <20081203194849.GQ8950@kroah.com> <1232686261.9977.1296303473@webmail.messagingengine.com> <20090123051620.GA8122@suse.de> <1232704065.25510.1296328851@webmail.messagingengine.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1232704065.25510.1296328851@webmail.messagingengine.com> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1977 Lines: 43 On Fri, Jan 23, 2009 at 08:47:45PM +1100, Bron Gondwana wrote: > On Thu, 22 Jan 2009 21:16 -0800, "Greg KH" wrote: > > > This is a kvm virtual machine running on a reasonably beefy external box, but > > > with 2Gb RAM allocated to the mx instance because that's all kvm would let me > > > use last time I checked. We're using KVM so the local copy of the database is > > > a little further away from the "internet facing side" and so we can build each > > > machine with our standard FAI setup. > > > > I would suggest just changing this default value then, it's a simple > > userspace configuration item, and for your boxes, it sounds like a > > larger value would be more suitable. > > Yes - I've pushed it up to 4096 now. Should be plenty! > > I guess Postfix is a bit of an odd case here. It runs lots of processes, yet > uses epoll within many of them as well - sort of a historical design in some ways, > but also to enforce maximum privilege separation with many of the daemons able to > be run under chroot with limited capabilities. > > So I guess I have a few questions left: > > 1) is this value ever supposed to be hit in practice by non-malicious software? > If not, it appears 128 is too low. It does appear a bit low. What looks to you like a good value to use as a default? > 2) if we're going to stick with 128, is there any way to query the kernel as to how > close to the limit it's getting? As an example, our system checks poll > /proc/sys/fs/file-max every 2 minutes, and warn us if its getting "full". Good idea, we should report this somewhere for the very reasons you suggest. Can you write up a patch to do this? If not, I'll see what I can do. thanks, greg k-h -- 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/