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=-8.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 6BDE7C31E46 for ; Wed, 12 Jun 2019 19:27:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3FC0121721 for ; Wed, 12 Jun 2019 19:27:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=arista.com header.i=@arista.com header.b="F2bLr6Us" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729237AbfFLT1X (ORCPT ); Wed, 12 Jun 2019 15:27:23 -0400 Received: from mail-wr1-f66.google.com ([209.85.221.66]:35162 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729106AbfFLT1J (ORCPT ); Wed, 12 Jun 2019 15:27:09 -0400 Received: by mail-wr1-f66.google.com with SMTP id m3so18175690wrv.2 for ; Wed, 12 Jun 2019 12:27:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=googlenew; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=Gc99P+6N6+xSxQKHKwT0OD+Dx6Ni+QOkx9u56EzlVmA=; b=F2bLr6Usjp0SS+YH0qbHW4ub7lF+EA48coYkSUubqCXi4L86a8pbijVIRgDvpuSUsF ZrK1Shovt+bDl648RmoiYd0gtNwx38PveHrl2akp0/4gVW6L1gdnFMajsh3iPjGadno4 0w+RVcfN1Az3gqf8b2lwzW/qAfl1AeEaqkzUE8yrXIb0ZD+g6RdrTckRWUM0PhWrh2oF jusm5g5Vb6YDoIbI3gf+RwyYIJ0n0S8J7fniaqQsd3uOABGpnTgA2gFyawsrYMQJbKbD hsRJOs43wENKcjTM9+yzTYzgj4XFg6jPN7rkBT7t0taep/aGmnhvlMKjsoLzm5ssPtn7 fTuQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Gc99P+6N6+xSxQKHKwT0OD+Dx6Ni+QOkx9u56EzlVmA=; b=aoCiLeFcMaQbg699mITRrRJ5CTscDHN86+0RQKJ7GxFs9zEvhHNsifPJMXtTdcFzK3 e7YgNGWY5cL+5duehQXBYW1K32BE1h4Vo2YLolm5JSRoukg1Rxt4jgochtAhRO47PMX8 S3cBKRYR0QLaHaCQ1XWXrDE45pIfH9G8t9OWaOK5n1C3Da0Bt8XuUENbR7QWIrmmYH00 yTwa+A5/x+OZlcMcMu3DuiI7zzqwOYXX0AtDwF9G/jVSBRztnLvflCYnQPEA9YsrSajs K/t0PLUFUKLCjXeIZJ8MeY6NEolSDom4TuEbE0Kr2i6qVBIK2gK6CFEW7/nzX5hmdUPu YsPw== X-Gm-Message-State: APjAAAV/dcDg2ckcQ+R3w3cWw0+cFK5/BoKva4MyXj4JkhYxXb1HBort IJXFr5gnbov9APAC+TpCOVEaLftsFBU= X-Google-Smtp-Source: APXvYqxIsPY4F76dTJDcOjFZdmSdKlq0GPIonqcAmCK2zG2wSLgAsYvCqwuGTkiuPGkT6q30d63hgw== X-Received: by 2002:adf:ee42:: with SMTP id w2mr42257126wro.253.1560367627677; Wed, 12 Jun 2019 12:27:07 -0700 (PDT) Received: from Mindolluin.ire.aristanetworks.com ([217.173.96.166]) by smtp.gmail.com with ESMTPSA id r5sm612526wrg.10.2019.06.12.12.27.06 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 12 Jun 2019 12:27:07 -0700 (PDT) From: Dmitry Safonov To: linux-kernel@vger.kernel.org Cc: Andrei Vagin , Dmitry Safonov , Adrian Reber , Andrei Vagin , Andy Lutomirski , Arnd Bergmann , Christian Brauner , Cyrill Gorcunov , Dmitry Safonov <0x7f454c46@gmail.com>, "Eric W. Biederman" , "H. Peter Anvin" , Ingo Molnar , Jann Horn , Jeff Dike , Oleg Nesterov , Pavel Emelyanov , Shuah Khan , Thomas Gleixner , Vincenzo Frascino , containers@lists.linux-foundation.org, criu@openvz.org, linux-api@vger.kernel.org, x86@kernel.org Subject: [PATCHv4 26/28] x86/vdso: Align VDSO functions by CPU L1 cache line Date: Wed, 12 Jun 2019 20:26:25 +0100 Message-Id: <20190612192628.23797-27-dima@arista.com> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190612192628.23797-1-dima@arista.com> References: <20190612192628.23797-1-dima@arista.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andrei Vagin After performance testing VDSO patches a noticeable 20% regression was found on gettime_perf selftest with a cold cache. As it turns to be, before time namespaces introduction, VDSO functions were quite aligned to cache lines, but adding a new code to adjust timens offset inside namespace created a small shift and vdso functions become unaligned on cache lines. Add align to vdso functions with gcc option to fix performance drop. Coping the resulting numbers from cover letter: Hot CPU cache (more gettime_perf.c cycles - the better): | before | CONFIG_TIME_NS=n | host | inside timens --------|------------|------------------|-------------|------------- cycles | 139887013 | 139453003 | 139899785 | 128792458 diff (%)| 100 | 99.7 | 100 | 92 Cold cache (lesser tsc per gettime_perf_cold.c cycle - the better): | before | CONFIG_TIME_NS=n | host | inside timens --------|------------|------------------|-------------|------------- tsc | 6748 | 6718 | 6862 | 12682 diff (%)| 100 | 99.6 | 101.7 | 188 Measured on Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz Co-developed-by: Dmitry Safonov Signed-off-by: Andrei Vagin Signed-off-by: Dmitry Safonov --- arch/x86/entry/vdso/Makefile | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index b58d34120fd8..c7bfd62d1fc3 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -4,6 +4,7 @@ # KBUILD_CFLAGS += $(DISABLE_LTO) +KBUILD_CFLAGS += -falign-functions=$(CONFIG_X86_L1_CACHE_SHIFT) KASAN_SANITIZE := n UBSAN_SANITIZE := n OBJECT_FILES_NON_STANDARD := y -- 2.22.0