Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754474Ab0DFOsM (ORCPT ); Tue, 6 Apr 2010 10:48:12 -0400 Received: from mail-pv0-f174.google.com ([74.125.83.174]:45267 "EHLO mail-pv0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754729Ab0DFOsF convert rfc822-to-8bit (ORCPT ); Tue, 6 Apr 2010 10:48:05 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type:content-transfer-encoding; b=QGRt6+TuMRdFejvBh+fyyeP7BMYRvGkfXvHwgz/SNguNVphRR64UVaKpiDrn1o14wO CeS3jjWiZXlGg50f4VNI2wo7/ywzRReZ3dXKn5eEub1YXrJrrsyVsxBLEFmju4xTqZYW 51Epxulb5xGiv+iseM/3ZTMcTpDEqmn0d+peE= MIME-Version: 1.0 In-Reply-To: <1270543721.1597.748.camel@laptop> References: <1270499039-23728-1-git-send-email-dvhltc@us.ibm.com> <4BBA5305.7010002@redhat.com> <1270543721.1597.748.camel@laptop> From: Ulrich Drepper Date: Tue, 6 Apr 2010 07:47:41 -0700 Message-ID: Subject: Re: [PATCH V2 0/6][RFC] futex: FUTEX_LOCK with optional adaptive spinning To: Peter Zijlstra Cc: Avi Kivity , Darren Hart , linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Eric Dumazet , "Peter W. Morreale" , Rik van Riel , Steven Rostedt , Gregory Haskins , Sven-Thorsten Dietrich , Chris Mason , John Cooper , Chris Wright Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 772 Lines: 18 On Tue, Apr 6, 2010 at 01:48, Peter Zijlstra wrote: >  try >  spin >  try >  syscall This is available for a long time in the mutex implementation (PTHREAD_MUTEX_ADAPTIVE_NP mutex type). It hasn't show much improvement if any. There were some people demanding this support for as far as I know they are not using it now. This is adaptive spinning, learning from previous calls how long to wait. But it's still unguided. There is no way to get information like "the owner has been descheduled". -- 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/