Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752348AbbBVMvX (ORCPT ); Sun, 22 Feb 2015 07:51:23 -0500 Received: from mail.skyhub.de ([78.46.96.112]:34267 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751915AbbBVMvV (ORCPT ); Sun, 22 Feb 2015 07:51:21 -0500 Date: Sun, 22 Feb 2015 13:50:23 +0100 From: Borislav Petkov To: Ingo Molnar Cc: Andy Lutomirski , Oleg Nesterov , Rik van Riel , x86@kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , Arjan van de Ven Subject: Re: [RFC PATCH] x86, fpu: Use eagerfpu by default on all CPUs Message-ID: <20150222125023.GC7529@pd.tnic> References: <20150221093150.GA27841@gmail.com> <20150221163840.GA32073@pd.tnic> <20150221172914.GB32073@pd.tnic> <20150221183952.GD8406@gmail.com> <20150221191527.GC32073@pd.tnic> <20150221192352.GA10027@gmail.com> <20150221213625.GD32073@pd.tnic> <20150222081840.GA22972@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20150222081840.GA22972@gmail.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1842 Lines: 66 On Sun, Feb 22, 2015 at 09:18:40AM +0100, Ingo Molnar wrote: > - It might make sense to do a 'perf stat --null --repeat' > measurement as well [without any -e arguments], to make > sure the rich PMU stats you are gathering are not > interfering? Well, the --repeat thing definitely is good to do and the previous single run is simply not meaningful due to variance I'd guess: perf stat --null --repeat 10 --sync --pre ~/bin/pre-build-kernel.sh make -s -j12 ... Lazy FPU: FPU saves before: 5 Setup is 16252 bytes (padded to 16384 bytes). System is 4222 kB CRC 5417fa4f Kernel: arch/x86/boot/bzImage is ready (#43) ... Kernel: arch/x86/boot/bzImage is ready (#52) Performance counter stats for 'make -s -j12' (10 runs): 219.406449195 seconds time elapsed ( +- 0.17% ) FPU saves after: 6974975 Eager FPU: FPU saves before: 4 Setup is 16252 bytes (padded to 16384 bytes). System is 4222 kB CRC 823c1801 Kernel: arch/x86/boot/bzImage is ready (#53) ... Kernel: arch/x86/boot/bzImage is ready (#62) Performance counter stats for 'make -s -j12' (10 runs): 218.791122148 seconds time elapsed ( +- 0.13% ) FPU saves after: 8939084 The counter numbers are consistent with before: ~200000 FPU saves more in eager mode per kernel build. Timing improvement of 0.6 secs on average looks nice to me. Next I'll do the same thing in tmpfs to see how the numbers look without the page cache. -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- -- 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/