Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752409Ab2BPO3w (ORCPT ); Thu, 16 Feb 2012 09:29:52 -0500 Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:59182 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752160Ab2BPO3v (ORCPT ); Thu, 16 Feb 2012 09:29:51 -0500 Date: Thu, 16 Feb 2012 14:31:32 +0000 From: Alan Cox To: Matthew Garrett Cc: Thomas Gleixner , LKML , Arjan van de Ven , Peter Zijlstra Subject: Re: [PATCH] hrtimers: Special-case zero length sleeps Message-ID: <20120216143132.293c8f50@pyramind.ukuu.org.uk> In-Reply-To: <20120216142733.GA15632@srcf.ucam.org> References: <1317308372-6810-1-git-send-email-mjg@redhat.com> <20120215145225.GA21448@srcf.ucam.org> <20120215202221.GA29552@srcf.ucam.org> <20120215203814.GA29795@srcf.ucam.org> <20120215204757.GA30275@srcf.ucam.org> <20120216142733.GA15632@srcf.ucam.org> X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.8; x86_64-redhat-linux-gnu) Face: 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 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 671 Lines: 16 > Userspace clearly has an expectation that sleep(0) is magic in some > ill-defined way. We'd be well within our rights to break that > expectation, but I think it's common enough to warrant special casing. In historical Unix sleep(0) ends up the nearest equivalent it had to triggering a reschedule and giving up the rest of the timeslice. I suspect special casing it as yield() isn't far from the right result ? Alan -- 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/