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=-2.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_HIGH,UNPARSEABLE_RELAY,URIBL_BLOCKED,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 8303BECDE5F for ; Thu, 19 Jul 2018 20:57:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3342C2084E for ; Thu, 19 Jul 2018 20:57:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="BPypYOz9" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3342C2084E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731587AbeGSVme (ORCPT ); Thu, 19 Jul 2018 17:42:34 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:45556 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729209AbeGSVmd (ORCPT ); Thu, 19 Jul 2018 17:42:33 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w6JKs8NE191526; Thu, 19 Jul 2018 20:56:43 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : subject : date : message-id : in-reply-to : references; s=corp-2018-07-02; bh=RiGhTN6g///YxNlAnsuvWKTlhs2d21Xsjt/HDHC/SIs=; b=BPypYOz9NGl8+/ID03oJ6HOvUgvEr/IFStGTKbP0SFGp22e3tWsQmBhgqlfkVaear8Br kjS9hcnWi0U6uBDH/4z8YGIi1uzU6JbB1meqCkRysENTDm2A97ANUmw2RRkyrRe7EzCo Uz4d3/SVNtBMh2m7iS+uMYoZOsIfO8vftfCpDiGz/DlBst5FyFeusP/R/3nfuUGzUMle eNjODjHkOIrQvN44u9uG9s33iXWp4c7r8p5+gIYuHn3tDe/4vrNgML7U0mrDGsnCxGwV DnvMbff+XV8GaGcvfobxKI2+pt0chVvCx9we2gbx0FxXbfhEFI97nPHjapuhMfV7APZf Dg== Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by aserp2120.oracle.com with ESMTP id 2k9yjgrufx-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 19 Jul 2018 20:56:43 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userv0021.oracle.com (8.14.4/8.14.4) with ESMTP id w6JKugsI013653 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 19 Jul 2018 20:56:42 GMT Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id w6JKufXs027541; Thu, 19 Jul 2018 20:56:42 GMT Received: from localhost.localdomain (/73.69.118.222) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 19 Jul 2018 20:56:41 +0000 From: Pavel Tatashin To: steven.sistare@oracle.com, daniel.m.jordan@oracle.com, linux@armlinux.org.uk, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, john.stultz@linaro.org, sboyd@codeaurora.org, x86@kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, douly.fnst@cn.fujitsu.com, peterz@infradead.org, prarit@redhat.com, feng.tang@intel.com, pmladek@suse.com, gnomes@lxorguk.ukuu.org.uk, linux-s390@vger.kernel.org, pasha.tatashin@oracle.com, boris.ostrovsky@oracle.com, jgross@suse.com, pbonzini@redhat.com Subject: [PATCH v15 16/26] time: default boot time offset to local_clock() Date: Thu, 19 Jul 2018 16:55:35 -0400 Message-Id: <20180719205545.16512-17-pasha.tatashin@oracle.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180719205545.16512-1-pasha.tatashin@oracle.com> References: <20180719205545.16512-1-pasha.tatashin@oracle.com> X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8959 signatures=668706 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=830 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1806210000 definitions=main-1807190218 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org read_persistent_wall_and_boot_offset() is called during boot to read both the persistent clock and also return the offset between the boot time and the value of persistent clock. Change the default boot_offset from zero to local_clock() so architectures, that do not have a dedicated boot_clock but have early sched_clock(), such as SPARCv9, x86, and possibly more will benefit from this change by getting a better and more consistent estimate of the boot time without need for an arch specific implementation. Signed-off-by: Pavel Tatashin --- kernel/time/timekeeping.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index cb738f825c12..30d7f64ffc87 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1503,14 +1503,17 @@ void __weak read_persistent_clock64(struct timespec64 *ts64) * Weak dummy function for arches that do not yet support it. * wall_time - current time as returned by persistent clock * boot_offset - offset that is defined as wall_time - boot_time - * default to 0. + * The default function calculates offset based on the current value of + * local_clock(). This way architectures that support sched_clock() but don't + * support dedicated boot time clock will provide the best estimate of the + * boot time. */ void __weak __init read_persistent_wall_and_boot_offset(struct timespec64 *wall_time, struct timespec64 *boot_offset) { read_persistent_clock64(wall_time); - *boot_offset = (struct timespec64){0}; + *boot_offset = ns_to_timespec64(local_clock()); } /* Flag for if timekeeping_resume() has injected sleeptime */ -- 2.18.0