From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268029AbUHKL0s (ORCPT ); Wed, 11 Aug 2004 07:26:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268024AbUHKL0s (ORCPT ); Wed, 11 Aug 2004 07:26:48 -0400 Received: from mail016.syd.optusnet.com.au ([211.29.132.167]:5769 "EHLO mail016.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S268028AbUHKL01 (ORCPT ); Wed, 11 Aug 2004 07:26:27 -0400 Message-ID: <411A024B.6060100@kolivas.org> Date: Wed, 11 Aug 2004 21:26:03 +1000 From: Con Kolivas User-Agent: Mozilla Thunderbird 0.7.1 (X11/20040626) X-Accept-Language: en-us, en MIME-Version: 1.0 To: "Prakash K. Cheemplavam" Cc: linux kernel mailing list Subject: Re: Scheduler fairness problem on 2.6 series References: <20040811022143.4892.qmail@web13910.mail.yahoo.com> <4119F3D9.7040708@gmx.de> In-Reply-To: <4119F3D9.7040708@gmx.de> X-Enigmail-Version: 0.84.1.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig95D1C2153158E808A3730D33" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig95D1C2153158E808A3730D33 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Prakash K. Cheemplavam wrote: > Con Kolivas wrote: > | I tried this on the latest staircase patch (7.I) and am not getting any > | output from your script when tested up to 60 threads on my hardware. Can > | you try this version of staircase please? > | > | There are 7.I patches against 2.6.8-rc4 and 2.6.8-rc4-mm1 > | > | http://ck.kolivas.org/patches/2.6/2.6.8/ > > Hi, > > I just updated to 2.6.8-rc4-ck2 and tried the two options interactive > and compute. Is the compute stuff functional? I tried setting it to 1 > within X and after that X wasn't usable anymore (meaning it looked like > locked up, frozen/gone mouse cursor even). I managed to switch back to > console and set it to 0 and all was OK again. Compute is very functional. However it isn't remotely meant to be run on a desktop because of very large scheduling latencies (on purpose). > The interactive to 0 setting helped me with runnign locally multiple > processes using mpi. Nevertheless (only with interactive 1 regression to > vanilla scheduler, else same) can't this be enhanced? I don't understand your question. Can what be enhanced? > Details: I am working on a load balancing class using mpi. For testing > purpises I am running multiple processes on my machine. So for a given > problem I can say, it needs x time to solve. Using more processes opn a > single machine, this time (except communication and balancing overhead) > shouldn't be much larger. Unfortunately this happens. Eg. a given > probelm using two processes needs about 20 seconds to finish. But using > 8 it already needs 47s (55s with interactiv set to 1). No, my balancing > framework is quite good. On a real (small, even larger till 128 nodes > tested) cluster overhead is just as low as 3% to 5%, ie. it scales quite > linearly. Once again I dont quite understand you. Are you saying that there is more than 50% cpu overhead when running 8 processes? Or that the cpu is distributed unfairly such that the longest will run for 47s? > Any idea how to tweak the staircase to get near the 20 seconds with more > processes? Or is this rather a problem of mpich used locally? Compute mode is by far the most scalable mode in staircase for purely computational tasks. The cost is that of interactivity; it is bad on purpose since it is a no-compromise maximum cpu cache utilisation policy. > If you like I can send you my code to test (beware it is not that small). > > Cheers, > > Prakash Cheers, Con --------------enig95D1C2153158E808A3730D33 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFBGgJOZUg7+tp6mRURAo6/AKCHHpsTye8ASdFafRQuXhgxsDx/mQCfcexP 21SXFLTjrVJn/lCQJmc/aUU= =UsyH -----END PGP SIGNATURE----- --------------enig95D1C2153158E808A3730D33--