Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S969467AbXFHPhd (ORCPT ); Fri, 8 Jun 2007 11:37:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764291AbXFHPhG (ORCPT ); Fri, 8 Jun 2007 11:37:06 -0400 Received: from MAIL.13thfloor.at ([213.145.232.33]:54982 "EHLO MAIL.13thfloor.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932768AbXFHPhB (ORCPT ); Fri, 8 Jun 2007 11:37:01 -0400 Date: Fri, 8 Jun 2007 17:37:00 +0200 From: Herbert Poetzl To: Pavel Emelianov Cc: Andrew Morton , Balbir Singh , Vaidyanathan Srinivasan , Linux Containers , Linux Kernel Mailing List , Kirill Korotaev Subject: Re: [PATCH 0/8] RSS controller based on process containers (v3.1) Message-ID: <20070608153700.GB27847@MAIL.13thfloor.at> Mail-Followup-To: Pavel Emelianov , Andrew Morton , Balbir Singh , Vaidyanathan Srinivasan , Linux Containers , Linux Kernel Mailing List , Kirill Korotaev References: <466412C5.1060104@openvz.org> <20070608120343.GA27847@MAIL.13thfloor.at> <46694E00.8020407@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <46694E00.8020407@openvz.org> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6749 Lines: 200 On Fri, Jun 08, 2007 at 04:39:28PM +0400, Pavel Emelianov wrote: > Herbert Poetzl wrote: > > On Mon, Jun 04, 2007 at 05:25:25PM +0400, Pavel Emelianov wrote: > >> Adds RSS accounting and control within a container. > >> > >> Changes from v3 > >> - comments across the code > >> - git-bisect safe split > >> - lost places to move the page between active/inactive lists > >> > >> Ported above Paul's containers V10 with fixes from Balbir. > >> > >> RSS container includes the per-container RSS accounting > >> and reclamation, and out-of-memory killer. > >> > >> > >> Each mapped page has an owning container and is linked into its > >> LRU lists just like in the global LRU ones. The owner of the page > >> is the container that touched the page first. > > > >> As long as the page stays mapped it holds the container, is accounted > >> into its usage and lives in its LRU list. When page is unmapped for > >> the last time it releases the container. > > > >> The RSS usage is exactly the number of pages in its booth LRU lists, > >> i.e. the nu,ber of pages used by this container. > > > > so there could be two guests, unified (i.e. sharing > > most of the files as hardlinks), where the first one > > holds 80% of the resulting pages, and the second one > > 20%, and thus shows much lower 'RSS' usage as the > > other one, although it is running the very same > > processes and providing identical services? > > Herbert!!! Where have you been so long? I was on vacation in april, and it took almost the entire may to process the backlog ... > You must have missed that we've decided not to account pages > sharing right now, but start with that model. Later we'll make > sharing accountable. well, there are two ways not to account sharing: 1) account it to the first user 2) account it to every user while the first one typically causes quite an imbalance when applied to shared resources (as Linux-VServer uses them), the latter one creates a new, but fair, metric for the usage to make that clear: we definitely prefer the latter one over the former, because we do not want to bring that imbalance to our shared guests (besides that, the second one doesn't add any overhead compared to the first one, more than that it probably simplifies the entire design) > ( There's something bad with my memory. I have a feeling that I > have already told that... many times... ) yeah, I have some kind of d?j? vu here too ... > >> When this usage exceeds the limit set some pages are reclaimed > >> from the owning container. In case no reclamation possible the OOM > >> killer starts thinning out the container. > > > > so the system (physical machine) starts reclaiming > > and probably swapping even when there is no need > > to do so? > > Good catch! The system will start reclaiming right when the > container hits the limit to expend its IO bandwidth. Not some > other's one that hit the global limit due to some bad container > was allowed to go above it. well, from the system PoV, a constantly swapping guest (on an otherwise unused host) is definitely something you do not really want, not to talk about a tightly packed host system, where guests start hogging the I/O with _unnecessary_ swapping > > e.g. a system with a single guest, limited to 10k > > pages, with a working set of 15k pages in different > > apps would continuously swap (trash?) on an otherwise > > unused (100k+ pages) system? > > > >> Thus the container behaves like a standalone machine - > >> when it runs out of resources, it tries to reclaim some > >> pages, and if it doesn't succeed, kills some task. > > > > is that really what we want? > > A kind of ;) okay, to clarify, we (Linux-VServer) do not want that behavior ... > > I think we can do _better_ than a standalone machine > > and in many cases we really should ... > > That's it! You are right - this is our ultimate goal. And we > plan to get there step by step. And we will appreciate your > patches fixing BUGS, improving the performance, extending the > functionality, etc. well, I would rip out the entire accounting and add a summation accounting as we do it right now, no problem with keeping the reclaim mechanisms though ... but I doubt that this is what you have in mind? > > best, > > Herbert > > Thanks for your attention, > Pavel just to make it clear, I don't want any limits in mainline which penalize the first started guest in a shared guest scenario .. or to rephrase, such a limit would be useless for our purpose best, Herbert > >> Signed-off-by: Pavel Emelianov > >> > >> The testing scenario may look like this: > >> > >> 1. Prepare the containers > >> # mkdir -p /containers/rss > >> # mount -t container none /containers/rss -o rss > >> > >> 2. Make the new group and move bash into it > >> # mkdir /containers/rss/0 > >> # echo $$ > /containers/rss/0/tasks > >> > >> Since now we're in the 0 container. > >> We can alter the RSS limit > >> # echo -n 6000 > /containers/rss/0/rss_limit > >> > >> We can check the usage > >> # cat /containers/rss/0/rss_usage > >> 25 > >> > >> And do other stuff. To check the reclamation to work we need a > >> simple program that touches many pages of memory, like this: > >> > >> #include > >> #include > >> #include > >> #include > >> > >> #ifndef PGSIZE > >> #define PGSIZE 4096 > >> #endif > >> > >> int main(int argc, char **argv) > >> { > >> unsigned long pages; > >> int i; > >> char *mem; > >> > >> if (argc < 2) { > >> printf("Usage: %s \n", argv[0]); > >> return 1; > >> } > >> > >> pages = strtol(argv[1], &mem, 10); > >> if (*mem != '\0') { > >> printf("Bad number %s\n", argv[1]); > >> return 1; > >> } > >> > >> mem = mmap(NULL, pages * PGSIZE, PROT_READ | PROT_WRITE, > >> MAP_PRIVATE | MAP_ANON, 0, 0); > >> if (mem == MAP_FAILED) { > >> perror("map"); > >> return 2; > >> } > >> > >> for (i = 0; i < pages; i++) > >> mem[i * PGSIZE] = 0; > >> > >> printf("OK\n"); > >> return 0; > >> } > >> _______________________________________________ > >> Containers mailing list > >> Containers@lists.linux-foundation.org > >> https://lists.linux-foundation.org/mailman/listinfo/containers > > - 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/