From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754798AbbAFKS6 (ORCPT ); Tue, 6 Jan 2015 05:18:58 -0500 Received: from casper.infradead.org ([85.118.1.10]:53202 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751698AbbAFKS5 (ORCPT ); Tue, 6 Jan 2015 05:18:57 -0500 Date: Tue, 6 Jan 2015 11:18:39 +0100 From: Peter Zijlstra To: Shaohua Li Cc: Andy Lutomirski , "linux-kernel@vger.kernel.org" , X86 ML , Kernel-team@fb.com, "H. Peter Anvin" , Ingo Molnar , John Stultz Subject: Re: [PATCH v2 3/3] X86: Add a thread cpu time implementation to vDSO Message-ID: <20150106101839.GN29390@twins.programming.kicks-ass.net> References: <8559794d3a1924408a811a2881ab916fffb6015b.1418857018.git.shli@fb.com> <95a7ba1a95a6251439d5ca2d3d56fe7f0778cb95.1418857018.git.shli@fb.com> <20141219112350.GJ30905@twins.programming.kicks-ass.net> <20141219170334.GM30905@twins.programming.kicks-ass.net> <20150102025953.GA1253265@devbig257.prn2.facebook.com> <20150105232337.GA391887@devbig257.prn2.facebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150105232337.GA391887@devbig257.prn2.facebook.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 05, 2015 at 03:23:38PM -0800, Shaohua Li wrote: > Good, it works. But the timestamp (.time_running and friends) only gets > updated for real hardware event between context switches. For software > event, the timestamp is initialized once, then never updated. If I use > it to get time, I actually get CLOCK_MONOTONIC. Hardware events work > well here, but depending on hardware event is too tricky, which I'd like > to avoid. Hmm, that's an unfortunate difference in behaviour, does something like the below cure that for you? --- kernel/events/core.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/events/core.c b/kernel/events/core.c index 4c1ee7f2bebc..0feb4e039359 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5965,11 +5965,13 @@ static void perf_swevent_del(struct perf_event *event, int flags) static void perf_swevent_start(struct perf_event *event, int flags) { event->hw.state = 0; + perf_event_update_userpage(event); } static void perf_swevent_stop(struct perf_event *event, int flags) { event->hw.state = PERF_HES_STOPPED; + perf_event_update_userpage(event); } /* Deref the hlist from the update side */ @@ -6410,12 +6412,14 @@ static void cpu_clock_event_start(struct perf_event *event, int flags) { local64_set(&event->hw.prev_count, local_clock()); perf_swevent_start_hrtimer(event); + perf_event_update_userpage(event); } static void cpu_clock_event_stop(struct perf_event *event, int flags) { perf_swevent_cancel_hrtimer(event); cpu_clock_event_update(event); + perf_event_update_userpage(event); } static int cpu_clock_event_add(struct perf_event *event, int flags) @@ -6484,12 +6488,14 @@ static void task_clock_event_start(struct perf_event *event, int flags) { local64_set(&event->hw.prev_count, event->ctx->time); perf_swevent_start_hrtimer(event); + perf_event_update_userpage(event); } static void task_clock_event_stop(struct perf_event *event, int flags) { perf_swevent_cancel_hrtimer(event); task_clock_event_update(event, event->ctx->time); + perf_event_update_userpage(event); } static int task_clock_event_add(struct perf_event *event, int flags)