Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751992AbXFYVKc (ORCPT ); Mon, 25 Jun 2007 17:10:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754170AbXFYVKC (ORCPT ); Mon, 25 Jun 2007 17:10:02 -0400 Received: from scrub.xs4all.nl ([194.109.195.176]:4488 "EHLO scrub.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753039AbXFYVKA (ORCPT ); Mon, 25 Jun 2007 17:10:00 -0400 From: Roman Zippel To: Ingo Molnar Subject: Re: [patch, v2.6.22-rc6] sys_time() speedup Date: Mon, 25 Jun 2007 23:09:46 +0200 User-Agent: KMail/1.9.7 Cc: linux-kernel@vger.kernel.org, Andrew Morton , John Stultz , Thomas Gleixner References: <20070625200601.GA18980@elte.hu> In-Reply-To: <20070625200601.GA18980@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200706252309.47467.zippel@linux-m68k.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1208 Lines: 41 Hi, On Monday 25 June 2007, Ingo Molnar wrote: > the patch improves the sysbench OLTP macrobenchmark significantly: Has that any real practical relevance? > @@ -373,6 +376,20 @@ void do_gettimeofday (struct timeval *tv > > tv->tv_sec = sec; > tv->tv_usec = usec; > + > + /* > + * Make sure xtime.tv_sec [returned by sys_time()] always > + * follows the gettimeofday() result precisely. This > + * condition is extremely unlikely, it can hit at most > + * once per second: > + */ > + if (unlikely(xtime.tv_sec != tv->tv_sec)) { > + unsigned long flags; > + > + write_seqlock_irqsave(&xtime_lock); > + update_wall_time(); > + write_seqlock_irqrestore(&xtime_lock); > + } > } > > EXPORT_SYMBOL(do_gettimeofday); Is this the do_gettimeofday() inside CONFIG_TIME_INTERPOLATION? What did you test? There can be many ways to read the clock, do you want to put this hook everywhere? Wouldn't it be better to improve the clock performance? bye, Roman - 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/