From patchwork Tue Dec 17 21:47:28 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adhemerval Zanella Netto X-Patchwork-Id: 1211761 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=sourceware.org (client-ip=209.132.180.131; helo=sourceware.org; envelope-from=libc-alpha-return-108178-incoming=patchwork.ozlabs.org@sourceware.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=linaro.org Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; secure) header.d=sourceware.org header.i=@sourceware.org header.b="v5QDk5Z2"; dkim=pass (2048-bit key; unprotected) header.d=linaro.org header.i=@linaro.org header.b="Fwkmz7HY"; 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 47csJ06dCFz9sRM for ; Wed, 18 Dec 2019 08:50:08 +1100 (AEDT) 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:subject:date:message-id:in-reply-to :references; q=dns; s=default; b=eYvj3oRCFpHoucpK8n++8LXCvQ12sDv AJcURkuY/eDJFP9m2aGZx7DjJ1K2pAderNOi8xKzXgoOEgNf8TzEdWBBnCn+L6SU gHAM83aihNcM3zZB6fKA/Ki7JcflWcgnuWEV1AjeKoSaMJwNH/c8hVsxp8fDWTlB I8lqc+UhBHcA= 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:subject:date:message-id:in-reply-to :references; s=default; bh=nWhrlHpJkWRQuIfMax4pY1zjrUE=; b=v5QDk 5Z2gLTmERWcUUexHLoEZEaceKijg71FqGS833Fcnc7At4U6IEJyTHeq1inxKtieb +GsnNgzaIhEnGZkxeoWcK8RvdqIl96HBcDzP9P+fWHkPzKTuOiN3w7a4QXfVTbXW 2Mdg+XXY0goyqPOXXvae4HvYZK60PZTAtqRaUM= Received: (qmail 112794 invoked by alias); 17 Dec 2019 21:48:04 -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 112106 invoked by uid 89); 17 Dec 2019 21:48:00 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-21.9 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=HX-Languages-Length:2092 X-HELO: mail-pj1-f65.google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:subject:date:message-id:in-reply-to:references; bh=EbVlLte6cM3D+rEIFJmkDeBnjV3lHOp6fJKNaMCCY8s=; b=Fwkmz7HYFhKXJpiNY5gDRdsMRBfSO6Vxg33ZvHf8KH9JMqBL3t/RgbMc8FL176NbCg MKSDluHrcdJ1u18KPFaz8mQzTit0AbWo/4hQwz1yu2mO9+81gFIaMyF5t178sEymojWo 2ud2BJNZ/ibu+w3WRfdE0PQiMIbFv16NPGNuhEUYFLyOPgVdgIny3lyPM5VlTlKINPsG UZHC7gipe3XOU3AXnamIZE4qAl6WTLtoAKTpGWPQ0Ua5wn4P3fLMdkT9YHy+DfQSj5ub xnU/kuKrpGgCFIfPekWP66WgMfAN5Vsr33KKigZUnf38lrhUtEG1+9rFPphgXJwMhmA7 w3FQ== From: Adhemerval Zanella To: libc-alpha@sourceware.org Subject: [PATCH 16/16] linux: Optimize fallback 32-bit clock_getres Date: Tue, 17 Dec 2019 18:47:28 -0300 Message-Id: <20191217214728.2886-16-adhemerval.zanella@linaro.org> In-Reply-To: <20191217214728.2886-1-adhemerval.zanella@linaro.org> References: <20191217214728.2886-1-adhemerval.zanella@linaro.org> This patch avoid probing the __NR_clock_getttime64 syscall each time __clock_gettime64 is issued on a kernel without 64 bit time support. Once ENOSYS is obtained, only 32-bit clock_gettime are used. The following snippet: clock_getres (CLOCK_REALTIME, &(struct timespec) { 0 }); clock_getres (CLOCK_MONOTONIC, &(struct timespec) { 0 }); clock_getres (CLOCK_BOOTTIME, &(struct timespec) { 0 }); clock_getres (20, &(struct timespec) { 0 }); On a kernel without 64 bit time support issues the syscalls: syscall_0x196(0, 0xffb83330, [...]) = -1 ENOSYS (Function not implemented) clock_getres(CLOCK_REALTIME, {tv_sec=0, tv_nsec=1}) = 0 clock_getres(CLOCK_MONOTONIC, {tv_sec=0, tv_nsec=1}) = 0 clock_getres(CLOCK_BOOTTIME, {tv_sec=0, tv_nsec=1}) = 0 Checked on i686-linux-gnu on 4.15 kernel. Reviewed-by: Siddhesh Poyarekar --- sysdeps/unix/sysv/linux/clock_getres.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/sysdeps/unix/sysv/linux/clock_getres.c b/sysdeps/unix/sysv/linux/clock_getres.c index 3d59f11d71..c1e1cf60c6 100644 --- a/sysdeps/unix/sysv/linux/clock_getres.c +++ b/sysdeps/unix/sysv/linux/clock_getres.c @@ -42,13 +42,21 @@ __clock_getres64 (clockid_t clock_id, struct __timespec64 *res) int r; /* Old 32-bit ABI with possible 64-bit time_t support. */ # ifdef __NR_clock_getres_time64 + /* Avoid issue a __NR_clock_getres_time64 syscall on kernels that do not + support 64-bit time_t. */ + static int time64_support = 1; + if (atomic_load_relaxed (&time64_support) == 1) + { # ifdef HAVE_CLOCK_GETRES64_VSYSCALL - r = INLINE_VSYSCALL (clock_getres_time64, 2, clock_id, res); + r = INLINE_VSYSCALL (clock_getres_time64, 2, clock_id, res); # else - r = INLINE_SYSCALL_CALL (clock_getres_time64, clock_id, res); + r = INLINE_SYSCALL_CALL (clock_getres_time64, clock_id, res); # endif - if (r == 0 || errno != ENOSYS) - return r; + if (r == 0 || errno != ENOSYS) + return r; + + atomic_store_relaxed (&time64_support, 0); + } # endif /* Fallback code that uses 32-bit support. */ struct timespec ts32;