From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Subject: Re: [RFC] sched: implement the exclusive wait queue as a LIFO queue Date: Wed, 28 Apr 2010 10:29:47 +0100 Message-ID: <8482.1272446987@redhat.com> References: <1272430986-20436-1-git-send-email-xiaosuo@gmail.com> <20100428081545.GA19027@windriver.com> Cc: dhowells@redhat.com, Yong Zhang , Xiaotian Feng , Ingo Molnar , Alexander Viro , Andrew Morton , "Eric W. Biederman" , Davide Libenzi , Roland Dreier , Stefan Richter , Peter Zijlstra , "David S. Miller" , Eric Dumazet , Christoph Lameter , Andreas Herrmann , Thomas Gleixner , Takashi Iwai , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Changli Gao Return-path: Received: from mx1.redhat.com ([209.132.183.28]:34682 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751043Ab0D1Jbn (ORCPT ); Wed, 28 Apr 2010 05:31:43 -0400 In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Changli Gao wrote: > If there isn't enough work to be done, we'd better not disrupt them > and leave them sleeping forever to keep the scheduler happier. Do we > have reason to keep fair to all the workers? Does it have benefit? You've made one important assumption: the processes on the wait queue are sleeping waiting to service things... but what if the wait queue governs access to a resource, and all the processes on that wait queue need access to that resource to do things? Some of the processes waiting for it may never get a go, and so necessary work may be left undone. So NACK. David