From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS17314 8.43.84.0/22 X-Spam-Status: No, score=-4.2 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED,SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server2.sourceware.org [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id 44C481F8C6 for ; Mon, 12 Jul 2021 10:40:33 +0000 (UTC) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 2AAFA382C403 for ; Mon, 12 Jul 2021 10:40:32 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 2AAFA382C403 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1626086432; bh=D0grHLqforGbGAgbc83hMPtzwmK6b8y9NqW6bPGz/2g=; h=To:Subject:References:Date:In-Reply-To:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=oFlvSkq0zUgP7JLvtVvNDh05qddShHSGeqSnLlytB2PqMCukSx1/Azs9dAcsbrPks 3L7jpu1cZj5uPSDTPzhcBmtUyW0cls3y9YVeGX30SD2314xP2lwjptGxwffULaoA8L /Y40aXDiaCFzwo7+MQe8F0XTEgUQSMTUc5LKgjGg= Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id 353BF3857C44 for ; Mon, 12 Jul 2021 10:40:12 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 353BF3857C44 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-215-iy89Yym1MoGbVEDNKi0ENQ-1; Mon, 12 Jul 2021 06:40:10 -0400 X-MC-Unique: iy89Yym1MoGbVEDNKi0ENQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 842A3800D62; Mon, 12 Jul 2021 10:40:09 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-103.rdu2.redhat.com [10.10.112.103]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AA9D360875; Mon, 12 Jul 2021 10:40:08 +0000 (UTC) To: Adhemerval Zanella Subject: Re: [PATCH] Linux: Use 32-bit vDSO for clock_gettime, gettimeofday, time (bug 28071) References: <87czrqf5un.fsf@oldenburg.str.redhat.com> <878s2ef19p.fsf@oldenburg.str.redhat.com> <874kd2ey6s.fsf@oldenburg.str.redhat.com> <158cdbcb-5335-9ff4-cf3e-a45d8603d029@linaro.org> Date: Mon, 12 Jul 2021 12:40:05 +0200 In-Reply-To: <158cdbcb-5335-9ff4-cf3e-a45d8603d029@linaro.org> (Adhemerval Zanella's message of "Sat, 10 Jul 2021 17:30:08 -0300") Message-ID: <878s2bdddm.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Florian Weimer via Libc-alpha Reply-To: Florian Weimer Cc: libc-alpha@sourceware.org Errors-To: libc-alpha-bounces+e=80x24.org@sourceware.org Sender: "Libc-alpha" * Adhemerval Zanella: > Using the test (a slight modified one from the bug report): > > -- > #include > #include > #include > > int > main (void) > { > struct timespec ts; > errno = 0; > clock_gettime (CLOCK_REALTIME, &ts); > printf ("errno = %m (%d)\n", errno); > errno = 0; > clock_gettime (CLOCK_MONOTONIC, &ts); > printf ("errno = %m (%d)\n", errno); > } > -- > > I see no syscall on 5.11 kernel, only a clock_gettime (CLOCK_MONOTONIC) > on the 4.4 and a clock_gettime_time64 plus a clock_gettime on the 3.10. This still introduces a severe performance regression on older kernels. It may well make some exsting 32-bit applications unusable until the kernel is upgraded. I'm not sure if this is a good idea. At least I can see that the clobbering of errno is gone. Thanks, Florian