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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=ham 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 A4DB9C43613 for ; Thu, 20 Jun 2019 16:28:11 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7B6A82064A for ; Thu, 20 Jun 2019 16:28:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="madlahLR" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7B6A82064A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=saRVNoDXbN3/AIwOSDhpX62/IKultB8N+iV8fIzo2uc=; b=madlahLR3zT4Xe ge+qNGG116MTYfBtpXupCsQ3BssxHDWlsUHqzQPlAR5/hN4QPerrqnxkgODcwpphu8paaOUl52Gaz ZXeboBzN16u1ZLet1KQD1TdG2MRHb8dyqokP301E5qwzQzuHKTzyUg1uplJpjvLS2Lqm5njV+V0qJ KKSnbsmWvD/CeqdV9OOal2CfTWCasjxYnGbo7GogOZTEMD1Uaqvp2Xl+KWLr6IYtqO1vnI8xI3uO2 WRGR6WcsUif7fMPc0Prclqv8KBSQm7xkP8ALGJaPIzJoNWAaJdXeswuPMdjAWBh9VW/W4cZlKbbiM 6V/ZLm9WbTu3EEFQOTRg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hdzv0-0000ef-Fc; Thu, 20 Jun 2019 16:28:10 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hdzun-0000XB-IL for linux-arm-kernel@lists.infradead.org; Thu, 20 Jun 2019 16:28:01 +0000 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 497012B; Thu, 20 Jun 2019 09:27:56 -0700 (PDT) Received: from donnerap.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E69803F246; Thu, 20 Jun 2019 09:27:53 -0700 (PDT) Date: Thu, 20 Jun 2019 17:27:46 +0100 From: Andre Przywara To: Vincenzo Frascino Subject: Re: [PATCH v6 00/19] Unify vDSOs across more architectures Message-ID: <20190620172746.7f92cb14@donnerap.cambridge.arm.com> In-Reply-To: <20190530141531.43462-1-vincenzo.frascino@arm.com> References: <20190530141531.43462-1-vincenzo.frascino@arm.com> Organization: ARM X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; aarch64-unknown-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190620_092757_749878_6254D619 X-CRM114-Status: GOOD ( 13.36 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Peter Collingbourne , Arnd Bergmann , Huw Davies , Catalin Marinas , Daniel Lezcano , Will Deacon , linux-kernel@vger.kernel.org, Ralf Baechle , linux-mips@vger.kernel.org, Paul Burton , linux-kselftest@vger.kernel.org, Rasmus Villemoes , Russell King , Dmitry Safonov <0x7f454c46@gmail.com>, Mark Salyzyn , Shuah Khan , Thomas Gleixner , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 Cheers, Andre. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel