From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030967AbXDWC4t (ORCPT ); Sun, 22 Apr 2007 22:56:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030969AbXDWC4t (ORCPT ); Sun, 22 Apr 2007 22:56:49 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:46995 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030967AbXDWC4s (ORCPT ); Sun, 22 Apr 2007 22:56:48 -0400 Date: Mon, 23 Apr 2007 04:55:53 +0200 From: Ingo Molnar To: Nick Piggin Cc: linux-kernel@vger.kernel.org, Linus Torvalds , Andrew Morton , Con Kolivas , Mike Galbraith , Arjan van de Ven , Peter Williams , Thomas Gleixner , caglar@pardus.org.tr, Willy Tarreau , Gene Heskett , Mark Lord , Ulrich Drepper Subject: Re: [patch] CFS scheduler, -v5 Message-ID: <20070423025553.GA10407@elte.hu> References: <20070420140457.GA14017@elte.hu> <20070423011229.GA20367@elte.hu> <20070423012509.GA25162@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070423012509.GA25162@wotan.suse.de> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.1.7 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Nick Piggin wrote: > > the biggest user-visible change in -v5 are various interactivity > > improvements (especially under higher load) to fix reported > > regressions, and an improved way of handling nice levels. There's > > also a new sys_sched_yield_to() syscall implementation for i686 and > > x86_64. > > > > All known regressions have been fixed. (knock on wood) > > I think the granularity is still much too low. Why not increase it to > something more reasonable as a default? note that CFS's "granularity" value is not directly comparable to "timeslice length": > [ Note: while CFS's default preemption granularity is currently set to > 5 msecs, this value does not directly transform into timeslices: for > example two CPU-intense tasks will have effective timeslices of 10 > msecs with this setting. ] also, i just checked SD: 0.46 defaults to 8 msecs rr_interval (on 1 CPU systems), which is lower than the 10 msecs effective timeslice length CVS-v5 achieves on two CPU-bound tasks. (in -v6 i'll scale the granularity up a bit with the number of CPUs, like SD does. That should get the right result on larger SMP boxes too.) while i agree it's a tad too finegrained still, I agree with Con's choice: rather err on the side of being too finegrained and lose some small amount of throughput on cache-intense workloads like compile jobs, than err on the side of being visibly too choppy for users on the desktop. Ingo