Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752941AbZJGPFI (ORCPT ); Wed, 7 Oct 2009 11:05:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751216AbZJGPFH (ORCPT ); Wed, 7 Oct 2009 11:05:07 -0400 Received: from smtp2.ultrahosting.com ([74.213.174.253]:38782 "EHLO smtp.ultrahosting.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751215AbZJGPFF (ORCPT ); Wed, 7 Oct 2009 11:05:05 -0400 Date: Wed, 7 Oct 2009 10:42:11 -0400 (EDT) From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Mathieu Desnoyers cc: Peter Zijlstra , akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Pekka Enberg , Tejun Heo , Mel Gorman , mingo@elte.hu Subject: Re: [this_cpu_xx V5 19/19] SLUB: Experimental new fastpath w/o interrupt disable In-Reply-To: <20091007124628.GB27363@Krystal> Message-ID: References: <20091006233654.815079668@gentwo.org> <20091006233733.153341605@gentwo.org> <20091007025440.GB4664@Krystal> <1254906707.26976.225.camel@twins> <20091007124628.GB27363@Krystal> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1083 Lines: 31 On Wed, 7 Oct 2009, Mathieu Desnoyers wrote: > Yes, I understood this is what he was doing, but I wonder about the > impact on the scheduler. If we have: > > * Jiffy 1 -- timer interrupt > > * preempt disable > * Jiffy 2 -- timer interrupt > -> here, the scheduler is disabled, so the timer interrupt is skipped. > The scheduler depends on preempt_check_resched() at preempt_enable() > to execute in a bounded amount of time. preempt disable does not disable interrupts. The timer interrupt will occur. The scheduler may not reschedule another job on this processor when the timer interrupt calls the scheduler_tick. It may not do load balancing. > Also, preempt_enable here should be replaced with > preempt_enable_no_resched(). Used to have that in earlier incarnations but I saw a lot of these being removed lately. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/