From patchwork Mon Apr 22 17:56:20 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mathieu Desnoyers X-Patchwork-Id: 1088796 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=sourceware.org (client-ip=209.132.180.131; helo=sourceware.org; envelope-from=libc-alpha-return-101551-incoming=patchwork.ozlabs.org@sourceware.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=efficios.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; secure) header.d=sourceware.org header.i=@sourceware.org header.b="b68N/atX"; dkim=pass (2048-bit key; unprotected) header.d=efficios.com header.i=@efficios.com header.b="rFF7YRwE"; dkim-atps=neutral Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 44nvRC386pz9s3l for ; Tue, 23 Apr 2019 03:56:55 +1000 (AEST) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:cc:subject:date:message-id:in-reply-to :references; q=dns; s=default; b=Nacgb1biBVXNfG3HdLY0Q0XYWPhbuNC viW69Q4dKuIaeqC/OCjBYrTlnJvhQsroOH4Fw6iP856lroxmFiwmPn0t4Fssp+96 H3pj8YwE50F2VV49OJsZ86y7stdg45EvZpEB/3peea9y1Aw1t0Zht5DKaRvy5oN9 JyJvSxQxYfws= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:cc:subject:date:message-id:in-reply-to :references; s=default; bh=8bJvFSxqnziUG8eCtpna5d9r4F0=; b=b68N/ atXlghSU1v6Ceg4Va4tCG3gs0koXoUduZO5Oshww1Eo7fEpFnI3slBjGJz5wI2f3 9HD9mW+wOKHny3kU2XEOGf4thSys4JQLONZPByketpCOribSlr/MaYfc8Z+EqY7g uPZfy3SDFH1yo2Gg1fIcsgSSDZRV/bm2jiOig4= Received: (qmail 95906 invoked by alias); 22 Apr 2019 17:56:33 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 95797 invoked by uid 89); 22 Apr 2019 17:56:33 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-24.3 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, RCVD_IN_DNSWL_NONE, SPF_PASS autolearn=ham version=3.3.1 spammy=sk:carlos, HTo:U*carlos, U*carlos, sk:carlos@ X-HELO: mail.efficios.com DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com C70651A84B7 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1555955788; bh=gv9OMDSdXRCRrMDv4Oz+jp2qdf5RTtVFqawCqcGlMjw=; h=From:To:Date:Message-Id; b=rFF7YRwEE7JM1PioivBOsCo/uLvV/gKFtgi3yoOfb2Njep7d1tJ5BZgM3zrtg2s3Z oz+K+0t5KjKeYnVeATWM1rolDG5OaNRbN3TSijL+V2il1G6sLyclWv7CGapRRn67vw 1gOPenF+MK3qvF1koOmHe29RowkE4wji4ETagyld5/T7p66VqZFAmS3x7GKrbBI3vn oiQGNBbI9FHKW+sYp1fr+NEqdJ8nFOYBLTC/VJJ9OG7YP6kse5I5ZDRA5SmD7gduix /AmdBY6aphk7InRxBkfciA9GYDuIta462tG/1btGavHR9dzwniFBtCYqnxecs2zxCW KgpGsJiHMlR+Q== From: Mathieu Desnoyers To: Carlos O'Donell Cc: Florian Weimer , Joseph Myers , Szabolcs Nagy , libc-alpha@sourceware.org, Mathieu Desnoyers , Thomas Gleixner , Ben Maurer , Peter Zijlstra , "Paul E. McKenney" , Boqun Feng , Will Deacon , Dave Watson , Paul Turner , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org Subject: [PATCH 2/5] glibc: sched_getcpu(): use rseq cpu_id TLS on Linux (v3) Date: Mon, 22 Apr 2019 13:56:20 -0400 Message-Id: <20190422175623.6134-3-mathieu.desnoyers@efficios.com> In-Reply-To: <20190422175623.6134-1-mathieu.desnoyers@efficios.com> References: <20190422175623.6134-1-mathieu.desnoyers@efficios.com> When available, use the cpu_id field from __rseq_abi on Linux to implement sched_getcpu(). Fall-back on the vgetcpu vDSO if unavailable. Benchmarks: x86-64: Intel E5-2630 v3@2.40GHz, 16-core, hyperthreading glibc sched_getcpu(): 13.7 ns (baseline) glibc sched_getcpu() using rseq: 2.5 ns (speedup: 5.5x) inline load cpuid from __rseq_abi TLS: 0.8 ns (speedup: 17.1x) Signed-off-by: Mathieu Desnoyers CC: Carlos O'Donell CC: Florian Weimer CC: Joseph Myers CC: Szabolcs Nagy CC: Thomas Gleixner CC: Ben Maurer CC: Peter Zijlstra CC: "Paul E. McKenney" CC: Boqun Feng CC: Will Deacon CC: Dave Watson CC: Paul Turner CC: libc-alpha@sourceware.org CC: linux-kernel@vger.kernel.org CC: linux-api@vger.kernel.org --- Changes since v1: - rseq is only used if both __NR_rseq and RSEQ_SIG are defined. Changes since v2: - remove duplicated __rseq_abi extern declaration. --- sysdeps/unix/sysv/linux/sched_getcpu.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/sysdeps/unix/sysv/linux/sched_getcpu.c b/sysdeps/unix/sysv/linux/sched_getcpu.c index fb0d317f83..167976fab7 100644 --- a/sysdeps/unix/sysv/linux/sched_getcpu.c +++ b/sysdeps/unix/sysv/linux/sched_getcpu.c @@ -24,8 +24,8 @@ #endif #include -int -sched_getcpu (void) +static int +vsyscall_sched_getcpu (void) { #ifdef __NR_getcpu unsigned int cpu; @@ -37,3 +37,23 @@ sched_getcpu (void) return -1; #endif } + +#ifdef __NR_rseq +#include +#endif + +#if defined __NR_rseq && defined RSEQ_SIG +int +sched_getcpu (void) +{ + int cpu_id = __rseq_abi.cpu_id; + + return cpu_id >= 0 ? cpu_id : vsyscall_sched_getcpu (); +} +#else +int +sched_getcpu (void) +{ + return vsyscall_sched_getcpu (); +} +#endif