Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 1 Nov 2001 06:10:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 1 Nov 2001 06:09:50 -0500 Received: from hermine.idb.hist.no ([158.38.50.15]:49413 "HELO hermine.idb.hist.no") by vger.kernel.org with SMTP id ; Thu, 1 Nov 2001 06:09:39 -0500 Message-ID: <3BE12D46.780477E@idb.hist.no> Date: Thu, 01 Nov 2001 12:08:54 +0100 From: Helge Hafting X-Mailer: Mozilla 4.76 [no] (X11; U; Linux 2.4.14-pre6 i686) X-Accept-Language: no, en MIME-Version: 1.0 To: Mark Hahn , linux-kernel@vger.kernel.org Subject: Re: graphical swap comparison of aa and rik vm In-Reply-To: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Mark Hahn wrote: > > > Here is the graph http://safemode.homeip.net/vm_swapcomparison.png . It's > > here's my munge of the same data: > http://mhahn.mcmaster.ca/~hahn/foo.png > the measures I find interesting are the SI/SO rates. first, the most obvious > feature is that Rik-VM has a serious problem knowing when to *stop* swapping > out. but SO isn't a bad thing unless it's obsessive: it's when you see high > *swap-in* that you know the VM has previously chosen bad pages to SO. Sure. SO isn't bad for the benchmark, but think of the guy trying to use the machine after the test finished. It probably swapped out a lot of other processes which is why you didn't see it swap in again. These things weren't needed for the bench, but daily use don't look like that. If my big job takes a long time - no problem if I can work on something else with nice performance. > and this is the second big difference: Rik-VM doesn't make nearly as many > mistakes - especially look at Andrea-VM thrashing out-in-out at ~ samples 26-32. > > also, if you merely sum the SI and SO columns for each: > sum(SI) sum(SO) sum(SI+SO) > Rik-VM 43564 317448 290032 > AA-VM 118284 171748 361012 > to me, this looks like the same point: Rik being SO-happy, > Andrea having to SI a lot more. interesting also that Andrea wins the race, > in spite of poorer SO choices and more swap traffic overall. It'd be real interesting to know wether or not the "excessive" swapping caused extra seeks. Readahead or simply reading more consecutive blocks don't hurt - while seeks do. Perhaps this is why it didn't hurt so much? Also consider the multiuser aspect - punishing a memory pig with extra swapin isn't necessarily so bad, if it keeps more memory around for others. Could possibly be bad for a dedicated box, but Andrea won on speed anyway. Helge Hafting - 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/