Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757591AbZAWRYg (ORCPT ); Fri, 23 Jan 2009 12:24:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751102AbZAWRY1 (ORCPT ); Fri, 23 Jan 2009 12:24:27 -0500 Received: from mail-ew0-f20.google.com ([209.85.219.20]:40534 "EHLO mail-ew0-f20.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754202AbZAWRY1 (ORCPT ); Fri, 23 Jan 2009 12:24:27 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=kVmkmg0gAfPks8o3LAax32yk/ODWn5kN6Tii02hc1IXjMwIOwUev6gIhODGoyPQq6I oLMB+95wwAZwEfZ8gmIoC5mhROyA/A0TpKLpIfsI8UEb9f1PVbOvtA4jc0MZEgzVXoM0 cViCX39P4qHwgvhXevYvQyVtWBbh9OsWITpaQ= MIME-Version: 1.0 In-Reply-To: <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> <20090123170631.GB11566@suse.de> Date: Fri, 23 Jan 2009 18:24:24 +0100 Message-ID: <195c7a900901230924n13ed225dq4aeff8015d22588e@mail.gmail.com> Subject: Re: [patch 016/104] epoll: introduce resource usage limits From: Bastien ROUCARIES To: Greg KH Cc: Bron Gondwana , Linux Kernel Mailing List , stable@kernel.org, Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2125 Lines: 46 On Fri, Jan 23, 2009 at 6:06 PM, Greg KH wrote: > 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. Why not using a ulimit for this kind of stuff ? Regards Bastien -- 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/