From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965479AbcFMKo0 (ORCPT ); Mon, 13 Jun 2016 06:44:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59331 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965140AbcFMKoZ (ORCPT ); Mon, 13 Jun 2016 06:44:25 -0400 Subject: Re: [PATCH v6 3/3] sched/cputime: Add steal time support to full dynticks CPU time accounting To: Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org References: <1465813966-3116-1-git-send-email-wanpeng.li@hotmail.com> <1465813966-3116-4-git-send-email-wanpeng.li@hotmail.com> Cc: Wanpeng Li , Ingo Molnar , "Peter Zijlstra (Intel)" , Rik van Riel , Thomas Gleixner , Frederic Weisbecker , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= From: Paolo Bonzini Message-ID: <6951b55f-7a5a-2635-bb48-d1d5d278d71a@redhat.com> Date: Mon, 13 Jun 2016 12:44:18 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 MIME-Version: 1.0 In-Reply-To: <1465813966-3116-4-git-send-email-wanpeng.li@hotmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Mon, 13 Jun 2016 10:44:24 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13/06/2016 12:32, Wanpeng Li wrote: > From: Wanpeng Li > > This patch adds guest steal-time support to full dynticks CPU > time accounting. After the following commit: > > ff9a9b4c4334 ("sched, time: Switch VIRT_CPU_ACCOUNTING_GEN to jiffy granularity") > > ... time sampling became jiffy based, even if it's still listening to ring > boundaries, so steal_account_process_tick() is reused to account how many > 'ticks' are stolen-time, after the last accumulation. > > Cc: Ingo Molnar > Cc: Peter Zijlstra (Intel) > Cc: Rik van Riel > Cc: Thomas Gleixner > Cc: Frederic Weisbecker > Cc: Paolo Bonzini > Cc: Radim Krčmář > Signed-off-by: Wanpeng Li > --- > kernel/sched/cputime.c | 16 +++++++++------- > 1 file changed, 9 insertions(+), 7 deletions(-) > > diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c > index 75f98c5..3d60e5d 100644 > --- a/kernel/sched/cputime.c > +++ b/kernel/sched/cputime.c > @@ -257,7 +257,7 @@ void account_idle_time(cputime_t cputime) > cpustat[CPUTIME_IDLE] += (__force u64) cputime; > } > > -static __always_inline bool steal_account_process_tick(void) > +static __always_inline unsigned long steal_account_process_tick(unsigned long max_jiffies) > { > #ifdef CONFIG_PARAVIRT > if (static_key_false(¶virt_steal_enabled)) { > @@ -272,14 +272,14 @@ static __always_inline bool steal_account_process_tick(void) > * time in jiffies. Lets cast the result to jiffies > * granularity and account the rest on the next rounds. > */ > - steal_jiffies = nsecs_to_jiffies(steal); > + steal_jiffies = min(nsecs_to_jiffies(steal), max_jiffies); > this_rq()->prev_steal_time += jiffies_to_nsecs(steal_jiffies); > > account_steal_time(jiffies_to_cputime(steal_jiffies)); > return steal_jiffies; > } > #endif > - return false; > + return 0; > } > > /* > @@ -346,7 +346,7 @@ static void irqtime_account_process_tick(struct task_struct *p, int user_tick, > u64 cputime = (__force u64) cputime_one_jiffy; > u64 *cpustat = kcpustat_this_cpu->cpustat; > > - if (steal_account_process_tick()) > + if (steal_account_process_tick(ULONG_MAX)) > return; > > cputime *= ticks; > @@ -477,7 +477,7 @@ void account_process_tick(struct task_struct *p, int user_tick) > return; > } > > - if (steal_account_process_tick()) > + if (steal_account_process_tick(ULONG_MAX)) > return; > > if (user_tick) > @@ -681,12 +681,14 @@ static cputime_t vtime_delta(struct task_struct *tsk) > static cputime_t get_vtime_delta(struct task_struct *tsk) > { > unsigned long now = READ_ONCE(jiffies); > - unsigned long delta = now - tsk->vtime_snap; > + unsigned long delta_jiffies, steal_jiffies; > > + delta_jiffies = now - tsk->vtime_snap; > + steal_jiffies = steal_account_process_tick(delta_jiffies); > WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE); > tsk->vtime_snap = now; > > - return jiffies_to_cputime(delta); > + return jiffies_to_cputime(delta_jiffies - steal_jiffies); > } > > static void __vtime_account_system(struct task_struct *tsk) > Reviewed-by: Paolo Bonzini