From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761617AbYCCKNJ (ORCPT ); Mon, 3 Mar 2008 05:13:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756508AbYCCKM4 (ORCPT ); Mon, 3 Mar 2008 05:12:56 -0500 Received: from gv-out-0910.google.com ([216.239.58.185]:39817 "EHLO gv-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756097AbYCCKMz (ORCPT ); Mon, 3 Mar 2008 05:12:55 -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=pbWz225ValX3S67Nc08cgHnm3RMTBaCu9Hf8mnu6f1OIrvr3C+k+j5qqQFNdlCTUxUO1FVSFnixa/Otsee57XXwnQ71UvotZZ2FDtKzWlCuCNKYceEKAPMH20GaTx5Qq/WF2HWTDymOIBgejVs8m7/RGIctCSP3kDJk2Gz+5aBE= Message-ID: Date: Mon, 3 Mar 2008 11:12:52 +0100 From: "Michael Kerrisk" To: "Ingo Molnar" Subject: Re: SCHED_IDLE documentation Cc: "Arnd Bergmann" , "Christoph Hellwig" , cbe-oss-dev@ozlabs.org, "Jeremy Kerr" , linux-kernel@vger.kernel.org In-Reply-To: <20080303100418.GF18281@elte.hu> 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> <20080303100418.GF18281@elte.hu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 3, 2008 at 11:04 AM, Ingo Molnar wrote: > > * 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? > > yes, even SCHED_IDLE tasks get some CPU time - so complete starvation > should not be possible. We dont really want to define the exact amount > of time they need. (we might want to change that in the future) But it > will always be less prio than nice +19 :-) You can think of it as if it > was "nice +30". > > > 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? > > they get equal share. > > you can try it out too: if you have 2.6.23 or newer kernels then just > pick up schedtool and use "schedtool -I" to run SCHED_IDLE tasks. Thanks for the answers Ingo! 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