Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751991Ab3F3WAO (ORCPT ); Sun, 30 Jun 2013 18:00:14 -0400 Received: from mail.skyhub.de ([78.46.96.112]:35664 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751320Ab3F3WAM (ORCPT ); Sun, 30 Jun 2013 18:00:12 -0400 Date: Mon, 1 Jul 2013 00:00:04 +0200 From: Borislav Petkov To: Wedson Almeida Filho Cc: Ingo Molnar , Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , Andrew Morton , Peter Zijlstra Subject: Re: [PATCH] x86: Use asm-goto to implement mutex fast path on x86-64 Message-ID: <20130630220004.GA23124@pd.tnic> References: <1372416851-56830-1-git-send-email-wedsonaf@gmail.com> <20130628111948.GA31065@gmail.com> <20130628140938.GA24819@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1245 Lines: 35 On Sat, Jun 29, 2013 at 04:56:30PM -0700, Wedson Almeida Filho wrote: > On Fri, Jun 28, 2013 at 7:09 AM, Borislav Petkov wrote: > > > Btw, do we have any perf data showing any improvements from this patch? > > I wrote a simple test the measures the time it takes to acquire and > release an uncontended mutex (i.e., we always take the fast path) > 100k times. I ran it a few times, the original code averages > 2.743436ms, and the new code averages 2.101098ms, so it's about 23% improvement. Microbenchmark results tend to be misleading in such situations. Rather, it would be much closer to reality if you traced a real workload like a simple kernel build, for example, with and without your patch. I.e., something like perf stat --repeat 5 ./build-kernel.sh and take a look at what the perfcouters are saying in both cases. > I also think the code looks cleaner this way. No doubt. -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. -- -- 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/