From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760712AbYCCKEN (ORCPT ); Mon, 3 Mar 2008 05:04:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754647AbYCCKD6 (ORCPT ); Mon, 3 Mar 2008 05:03:58 -0500 Received: from wa-out-1112.google.com ([209.85.146.178]:50091 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753671AbYCCKD5 (ORCPT ); Mon, 3 Mar 2008 05:03:57 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=w+OftBqOG0j2+PrOnCRHLPQLaOAbMhEmyOGxn8pRIUxqpFHajlBIGbEFL9Mfp0j6JBoo0EtvAgCKAdxtv+mZz2PYM7L+egqooV759zBl1lG9YFNUODT0xjcWG1L3iEVcMdxEovKZDVwRjURRv4+U9AnVzMC+FBpEfmkV4tZlMP4= Message-ID: Date: Mon, 3 Mar 2008 11:03:56 +0100 From: "Michael Kerrisk" To: "Arnd Bergmann" Subject: Re: SCHED_IDLE documentation Cc: "Ingo Molnar" , "Christoph Hellwig" , cbe-oss-dev@ozlabs.org, "Jeremy Kerr" , linux-kernel@vger.kernel.org In-Reply-To: <200803031031.52335.arnd@arndb.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <1203376368.275756.252634247263.1.gpush@pokey> <20080303092422.GA18281@elte.hu> <200803031031.52335.arnd@arndb.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 3, 2008 at 10:31 AM, Arnd Bergmann wrote: > On Monday 03 March 2008, Ingo Molnar wrote: > > > * What's the difference between SCHED_IDLE and SCHED_BATCH? > > > > SCHED_BATCH can still have nice levels from -20 to +19, it is a modified > > SCHED_OTHER/SCHED_NORMAL for "throughput oriented" workloads. > > > > SCHED_IDLE overrides the nice settings and it means a "super idle" > > workload. > > Does that mean that a SCHED_IDLE task still runs some of the time if > you have a CPU hog running on +19, or can any other process starve the > SCHED_IDLE task? Thanks. That was going to be my next question! I'm guessing that SCHED_IDLE doesn't get completely starved by a CPU hog running nice +19, but it would still be interesting to know: roughly how much of the CPU could the CPU_IDLE process expect to get in that case? > What happens if you have two SCHED_IDLE tasks on a single CPU, do they get > equal share, or will they just run as batch jobs? Also might be useful to add th e answer to this to the man page... Cheers, Michael -- Michael Kerrisk Maintainer of the Linux man-pages project http://www.kernel.org/doc/man-pages/ Want to report a man-pages bug? Look here: http://www.kernel.org/doc/man-pages/reporting_bugs.html