Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752650Ab0DFJA7 (ORCPT ); Tue, 6 Apr 2010 05:00:59 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:48694 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752173Ab0DFJAh (ORCPT ); Tue, 6 Apr 2010 05:00:37 -0400 Subject: Re: [PATCH V2 0/6][RFC] futex: FUTEX_LOCK with optional adaptive spinning From: Peter Zijlstra To: Avi Kivity Cc: 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 In-Reply-To: <4BBA5305.7010002@redhat.com> References: <1270499039-23728-1-git-send-email-dvhltc@us.ibm.com> <4BBA5305.7010002@redhat.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 06 Apr 2010 10:48:41 +0200 Message-ID: <1270543721.1597.748.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 638 Lines: 22 On Tue, 2010-04-06 at 00:15 +0300, Avi Kivity wrote: > > An interesting (but perhaps difficult to achieve) optimization would be > to spin in userspace. System call overhead isn't that large, but if you want to amortize that you can do a very small spin in userspace and then take the syscall: try spin try syscall like. Complicating anything beyond that is just not worth it. -- 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/