From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751050AbVLPFDq (ORCPT ); Fri, 16 Dec 2005 00:03:46 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751249AbVLPFDp (ORCPT ); Fri, 16 Dec 2005 00:03:45 -0500 Received: from e3.ny.us.ibm.com ([32.97.182.143]:53376 "EHLO e3.ny.us.ibm.com") by vger.kernel.org with ESMTP id S1751050AbVLPFDp (ORCPT ); Fri, 16 Dec 2005 00:03:45 -0500 Message-ID: <43A24A6F.5090907@us.ibm.com> Date: Thu, 15 Dec 2005 21:02:39 -0800 From: Sridhar Samudrala User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Matthew Dobson CC: Pavel Machek , linux-kernel@vger.kernel.org, andrea@suse.de, Andrew Morton , Linux Memory Management Subject: Re: [RFC][PATCH 0/6] Critical Page Pool References: <439FCECA.3060909@us.ibm.com> <20051214100841.GA18381@elf.ucw.cz> <43A0406C.8020108@us.ibm.com> <20051215162601.GJ2904@elf.ucw.cz> <43A1E551.1090403@us.ibm.com> In-Reply-To: <43A1E551.1090403@us.ibm.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Matthew Dobson wrote: >Pavel Machek wrote: > > >>>>And as you noticed, it does not work for your original usage case, >>>>because reserved memory pool would have to be "sum of all network >>>>interface bandwidths * ammount of time expected to survive without >>>>network" which is way too much. >>>> >>>> >>>Well, I never suggested it didn't work for my original usage case. The >>>discussion we had is that it would be incredibly difficult to 100% >>>iron-clad guarantee that the pool would NEVER run out of pages. But we can >>>size the pool, especially given a decent workload approximation, so as to >>>make failure far less likely. >>> >>> >>Perhaps you should add file in Documentation/ explaining it is not >>reliable? >> >> > >That's a good suggestion. I will rework the patch's additions to >Documentation/sysctl/vm.txt to be more clear about exactly what we're >providing. > > > > >>>>If you want few emergency pages for some strange hack you are doing >>>>(swapping over network?), just put swap into ramdisk and swapon() it >>>>when you are in emergency, or use memory hotplug and plug few more >>>>gigabytes into your machine. But don't go introducing infrastructure >>>>that _can't_ be used right. >>>> >>>> >>>Well, that's basically the point of posting these patches as an RFC. I'm >>>not quite so delusional as to think they're going to get picked up right >>>now. I was, however, hoping for feedback to figure out how to design >>>infrastructure that *can* be used right, as well as trying to find other >>>potential users of such a feature. >>> >>> >>Well, we don't usually take infrastructure that has no in-kernel >>users, and example user would indeed be nice. >> Pavel >> >> > >Understood. I certainly wouldn't expect otherwise. I'll see if I can get >Sridhar to post his networking changes that take advantage of this. > > I have posted these patches yesterday on lkml and netdev and here is a link to the thread. http://thread.gmane.org/gmane.linux.kernel/357835 Thanks Sridhar