From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 54E33C43613 for ; Fri, 21 Jun 2019 09:12:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3574F208C3 for ; Fri, 21 Jun 2019 09:12:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726309AbfFUJMD (ORCPT ); Fri, 21 Jun 2019 05:12:03 -0400 Received: from foss.arm.com ([217.140.110.172]:52154 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726210AbfFUJMD (ORCPT ); Fri, 21 Jun 2019 05:12:03 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 98C30360; Fri, 21 Jun 2019 02:12:02 -0700 (PDT) Received: from [10.1.196.72] (e119884-lin.cambridge.arm.com [10.1.196.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3041B3F246; Fri, 21 Jun 2019 02:12:00 -0700 (PDT) Subject: Re: [PATCH v6 00/19] Unify vDSOs across more architectures To: Andre Przywara Cc: linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-kselftest@vger.kernel.org, Shuah Khan , Arnd Bergmann , Huw Davies , Catalin Marinas , Daniel Lezcano , Will Deacon , Russell King , Ralf Baechle , Mark Salyzyn , Paul Burton , Dmitry Safonov <0x7f454c46@gmail.com>, Rasmus Villemoes , Thomas Gleixner , Peter Collingbourne References: <20190530141531.43462-1-vincenzo.frascino@arm.com> <20190620172746.7f92cb14@donnerap.cambridge.arm.com> From: Vincenzo Frascino Message-ID: <40c3e4e9-96d3-f940-f5cb-ed97762ef9b0@arm.com> Date: Fri, 21 Jun 2019 10:11:58 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190620172746.7f92cb14@donnerap.cambridge.arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On 20/06/2019 17:27, Andre Przywara wrote: > On Thu, 30 May 2019 15:15:12 +0100 > Vincenzo Frascino wrote: > > Hi, > >> vDSO (virtual dynamic shared object) is a mechanism that the Linux >> kernel provides as an alternative to system calls to reduce where >> possible the costs in terms of cycles. >> [ ... ] >> The porting has been benchmarked and the performance results are >> provided as part of this cover letter. > > I can't reveal the absolute numbers here, but vdsotest-bench gives me > quite some performance gain on my board here ("time needed on v6" divided > by "time needed on 5.2-rc1", so smaller percentages are better): > clock-gettime-monotonic: 23 % > clock-gettime-monotonic-raw: 30 % > clock-gettime-tai: 5 % > clock-getres-tai: 5 % > clock-gettime-boottime: 5 % > clock-getres-boottime: 5 % > clock-gettime-realtime: 25 % > gettimeofday: 26 % > The other numbers stayed the same or differed by just 1 ns, which seems to > be within the margin of error, as repeated runs on the same kernel suggest. > The 5% numbers are of course those were we went from a syscall-only to the > newly added arm64 VDSO implementation, but even the other calls improved > by a factor of 3 or more. > > Sounds like a strong indicator that this is a good thing to have. > > Not sure if "running some benchmark a couple of times on a single machine" > qualifies for this, but I guess it means: > > Tested-by: Andre Przywara > Thanks Andre, it sounds great! I will add your tag as well to my patches. > Cheers, > Andre. > -- Regards, Vincenzo