From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752419AbdKIDC4 (ORCPT ); Wed, 8 Nov 2017 22:02:56 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:42097 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751786AbdKIDCt (ORCPT ); Wed, 8 Nov 2017 22:02:49 -0500 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 Subject: [PATCH v8 0/6] Early boot time stamps for x86 Date: Wed, 8 Nov 2017 22:01:55 -0500 Message-Id: <20171109030201.5991-1-pasha.tatashin@oracle.com> X-Mailer: git-send-email 2.15.0 X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org changelog --------- v8 - v7 - Addressed comments from Dou Liyang: - Moved tsc_early_init() and tsc_early_fini() to be all inside tsc.c, and changed them to be static. - Removed warning when notsc parameter is used. - Merged with: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git v7 - v6 - Removed tsc_disabled flag, now notsc is equivalent of tsc=unstable - Simplified changes to sched/clock.c, by removing the sched_clock_early() and friends as requested by Peter Zijlstra. We know always use sched_clock() - Modified x86 sched_clock() to return either early boot time or regular. - Added another example why ealry boot time is important v5 - v6 - Added a new patch: time: sync read_boot_clock64() with persistent clock Which fixes missing __init macro, and enabled time discrepancy fix that was noted by Thomas Gleixner - Split "x86/time: read_boot_clock64() implementation" into a separate patch v4 - v5 - Fix compiler warnings on systems with stable clocks. v3 - v4 - Fixed tsc_early_fini() call to be in the 2nd patch as reported by Dou Liyang - Improved comment before __use_sched_clock_early to explain why we need both booleans. - Simplified valid_clock logic in read_boot_clock64(). v2 - v3 - Addressed comment from Thomas Gleixner - Timestamps are available a little later in boot but still much earlier than in mainline. This significantly simplified this work. v1 - v2 In patch "x86/tsc: tsc early": - added tsc_adjusted_early() - fixed 32-bit compile error use do_div() Adding early boot time stamps support for x86 machines. SPARC patches for early boot time stamps are already integrated into mainline linux. Sample output ------------- Before: https://hastebin.com/jadaqukubu.scala After: https://hastebin.com/nubipozacu.scala For more exaples how early time stamps are used, see this work: Example 1: https://lwn.net/Articles/734374/ - Without early boot time stamps we would not know about the extra time that is spent zeroing struct pages early in boot even when deferred page initialization. Example 2: https://patchwork.kernel.org/patch/10021247/ - If early boot timestamps were available, the engineer who introduced this bug would have noticed the extra time that is spent early in boot. Pavel Tatashin (6): x86/tsc: remove tsc_disabled flag time: sync read_boot_clock64() with persistent clock x86/time: read_boot_clock64() implementation sched: early boot clock x86/paravirt: add active_sched_clock to pv_time_ops x86/tsc: use tsc early arch/arm/kernel/time.c | 2 +- arch/s390/kernel/time.c | 2 +- arch/x86/include/asm/paravirt.h | 2 +- arch/x86/include/asm/paravirt_types.h | 1 + arch/x86/kernel/paravirt.c | 1 + arch/x86/kernel/time.c | 30 ++++++++++ arch/x86/kernel/tsc.c | 104 ++++++++++++++++++++++++++++------ arch/x86/xen/time.c | 7 ++- include/linux/timekeeping.h | 7 +-- kernel/sched/clock.c | 10 +++- kernel/time/timekeeping.c | 8 ++- 11 files changed, 144 insertions(+), 30 deletions(-) -- 2.15.0