From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267919AbUHKDoo (ORCPT ); Tue, 10 Aug 2004 23:44:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267921AbUHKDoo (ORCPT ); Tue, 10 Aug 2004 23:44:44 -0400 Received: from gizmo08bw.bigpond.com ([144.140.70.18]:21410 "HELO gizmo08bw.bigpond.com") by vger.kernel.org with SMTP id S267919AbUHKDoU (ORCPT ); Tue, 10 Aug 2004 23:44:20 -0400 Message-ID: <4119960A.4010002@bigpond.net.au> Date: Wed, 11 Aug 2004 13:44:10 +1000 From: Peter Williams User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 X-Accept-Language: en-us, en MIME-Version: 1.0 To: spaminos-ker@yahoo.com CC: Peter Williams , William Lee Irwin III , linux-kernel@vger.kernel.org Subject: Re: Scheduler fairness problem on 2.6 series (Attn: Nick Piggin and others) References: <20040811010116.GL11200@holomorphy.com> <20040811022143.4892.qmail@web13910.mail.yahoo.com> <20040811022345.GN11200@holomorphy.com> <41198859.7050807@bigpond.net.au> <411988DF.9010308@bigpond.net.au> <41199129.9080809@bigpond.net.au> In-Reply-To: <41199129.9080809@bigpond.net.au> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Peter Williams wrote: > Peter Williams wrote: > >> Peter Williams wrote: >> >>> William Lee Irwin III wrote: >>> >>>> On Tue, Aug 10, 2004 at 07:21:43PM -0700, spaminos-ker@yahoo.com wrote: >>>> >>>>> I am not very familiar with all the parameters, so I just kept the >>>>> defaults >>>>> Anything else I could try? >>>>> Nicolas >>>> >>>> >>>> >>>> >>>> >>>> No. It appeared that the SPA bits had sufficient fairness in them to >>>> pass this test but apparently not quite enough. >>>> >>> >>> The interactive bonus may interfere with fairness (the throughput >>> bonus should actually help it for tasks with equal nice) so you could >>> try setting max_ia_bonus to zero (and possibly increasing >>> max_tpt_bonus). With "eb" mode this should still give good >>> interactive response but expect interactive response to suffer a >>> little in "pb" mode however renicing the X server to a negative value >>> should help. >> >> >> >> I should also have mentioned that fiddling with the promotion interval >> may help. > > > Having reread your original e-mail I think that this problem is probably > being caused by the interactive bonus mechanism classifying the httpd > server threads as "interactive" threads and giving them a bonus. But > for some reason the daemon is not identified as "interactive" meaning > that it gets given a lower priority. In this situation if there's a > large number of httpd threads (even with promotion) it could take quite > a while for the daemon to get a look in. Without promotion total > starvation is even a possibility. > > Peter > PS For both "eb" and "pb" modes, max_io_bonus should be set to zero on > servers (where interactive responsiveness isn't an issue). > PPS For "sc" mode, try setting "interactive" to zero and "compute" to 1. I've just run your tests on my desktop and with max_ia_bonus at its default value I see the "delta = 3" with 20 threads BUT when I set max_ia_bonus to zero they stop (in both "eb" and "pb" mode). So I then reran the tests with 60 threads and zero max_ia_bonus and no output was generated by your testdelay script in either "eb" or "pb" modes. I didn't try "sc" mode as I have a ZAPHOD kernel loaded (not HYDRA) but Con has reported that the problem is absent in his latest patches so I'll update the "sc" mode in HYDRA to those patches. Peter -- Peter Williams pwil3058@bigpond.net.au "Learning, n. The kind of ignorance distinguishing the studious." -- Ambrose Bierce