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Groups > linux.kernel > #1402918 > unrolled thread

[PATCH v3] sched/cputime: add steal time support to full dynticks CPU time accounting

Started byWanpeng Li <kernellwp@gmail.com>
First post2016-05-18 14:30 +0200
Last post2016-05-25 12:40 +0200
Articles 4 — 3 participants

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  [PATCH v3] sched/cputime: add steal time support to full dynticks CPU time accounting Wanpeng Li <kernellwp@gmail.com> - 2016-05-18 14:30 +0200
    Re: [PATCH v3] sched/cputime: add steal time support to full  dynticks CPU time accounting Rik van Riel <riel@redhat.com> - 2016-05-24 21:30 +0200
      Re: [PATCH v3] sched/cputime: add steal time support to full dynticks  CPU time accounting Wanpeng Li <kernellwp@gmail.com> - 2016-05-25 04:20 +0200
        Re: [PATCH v3] sched/cputime: add steal time support to full dynticks  CPU time accounting Paolo Bonzini <pbonzini@redhat.com> - 2016-05-25 12:40 +0200

#1402918 — [PATCH v3] sched/cputime: add steal time support to full dynticks CPU time accounting

FromWanpeng Li <kernellwp@gmail.com>
Date2016-05-18 14:30 +0200
Subject[PATCH v3] sched/cputime: add steal time support to full dynticks CPU time accounting
Message-ID<rA8LT-25R-5@gated-at.bofh.it>
From: Wanpeng Li <wanpeng.li@hotmail.com>

This patch adds steal guest time support to full dynticks CPU 
time accounting. After 'commit ff9a9b4c4334 ("sched, time: Switch 
VIRT_CPU_ACCOUNTING_GEN to jiffy granularity")', time is jiffy 
based sampling even if it's still listened to ring boundaries, so 
steal_account_process_tick() is reused to account how much 'ticks' 
are steal time after the last accumulation. 

Suggested-by: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
v2 -> v3:
 * convert steal time jiffies to cputime
v1 -> v2:
 * fix divide zero bug, thanks Rik

 kernel/sched/cputime.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 75f98c5..f51c98c 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(void)
 {
 #ifdef CONFIG_PARAVIRT
 	if (static_key_false(&paravirt_steal_enabled)) {
@@ -279,7 +279,7 @@ static __always_inline bool steal_account_process_tick(void)
 		return steal_jiffies;
 	}
 #endif
-	return false;
+	return 0;
 }
 
 /*
@@ -691,8 +691,14 @@ static cputime_t get_vtime_delta(struct task_struct *tsk)
 
 static void __vtime_account_system(struct task_struct *tsk)
 {
+	cputime_t steal_time;
 	cputime_t delta_cpu = get_vtime_delta(tsk);
+	unsigned long delta_st = steal_account_process_tick();
+	steal_time = jiffies_to_cputime(delta_st);
 
+	if (steal_time >= delta_cpu)
+		return;
+	delta_cpu -= steal_time;
 	account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu));
 }
 
@@ -723,7 +729,16 @@ void vtime_account_user(struct task_struct *tsk)
 	write_seqcount_begin(&tsk->vtime_seqcount);
 	tsk->vtime_snap_whence = VTIME_SYS;
 	if (vtime_delta(tsk)) {
+		cputime_t steal_time;
+		unsigned long delta_st = steal_account_process_tick();
 		delta_cpu = get_vtime_delta(tsk);
+		steal_time = jiffies_to_cputime(delta_st);
+
+		if (steal_time >= delta_cpu) {
+			write_seqcount_end(&tsk->vtime_seqcount);
+			return;
+		}
+		delta_cpu -= steal_time;
 		account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
 	}
 	write_seqcount_end(&tsk->vtime_seqcount);
-- 
1.9.1

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#1406410 — Re: [PATCH v3] sched/cputime: add steal time support to full dynticks CPU time accounting

FromRik van Riel <riel@redhat.com>
Date2016-05-24 21:30 +0200
SubjectRe: [PATCH v3] sched/cputime: add steal time support to full dynticks CPU time accounting
Message-ID<rCqbE-7np-9@gated-at.bofh.it>
In reply to#1402918

[Multipart message — attachments visible in raw view] — view raw

On Wed, 2016-05-18 at 20:27 +0800, Wanpeng Li wrote:
> From: Wanpeng Li <wanpeng.li@hotmail.com>
> 
> This patch adds steal guest time support to full dynticks CPU 
> time accounting. After 'commit ff9a9b4c4334 ("sched, time: Switch 
> VIRT_CPU_ACCOUNTING_GEN to jiffy granularity")', time is jiffy 
> based sampling even if it's still listened to ring boundaries, so 
> steal_account_process_tick() is reused to account how much 'ticks' 
> are steal time after the last accumulation. 
> 
> Suggested-by: Rik van Riel <riel@redhat.com>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
> Cc: Rik van Riel <riel@redhat.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim <rkrcmar@redhat.com>
> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>

This also nicely fixes up f9c904b7613b ("sched/cputime: 
Fix steal_account_process_tick() to always return jiffies"),
which relies on a bool function returning a certain number
of jiffies :)

Reviewed-by: Rik van Riel <riel@redhat.com>

-- 
All rights reversed

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#1406560 — Re: [PATCH v3] sched/cputime: add steal time support to full dynticks CPU time accounting

FromWanpeng Li <kernellwp@gmail.com>
Date2016-05-25 04:20 +0200
SubjectRe: [PATCH v3] sched/cputime: add steal time support to full dynticks CPU time accounting
Message-ID<rCwAp-3nw-1@gated-at.bofh.it>
In reply to#1406410
Ping Paolo or Peterz.
2016-05-25 3:22 GMT+08:00 Rik van Riel <riel@redhat.com>:
> On Wed, 2016-05-18 at 20:27 +0800, Wanpeng Li wrote:
>> From: Wanpeng Li <wanpeng.li@hotmail.com>
>>
>> This patch adds steal guest time support to full dynticks CPU
>> time accounting. After 'commit ff9a9b4c4334 ("sched, time: Switch
>> VIRT_CPU_ACCOUNTING_GEN to jiffy granularity")', time is jiffy
>> based sampling even if it's still listened to ring boundaries, so
>> steal_account_process_tick() is reused to account how much 'ticks'
>> are steal time after the last accumulation.
>>
>> Suggested-by: Rik van Riel <riel@redhat.com>
>> Cc: Ingo Molnar <mingo@kernel.org>
>> Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
>> Cc: Rik van Riel <riel@redhat.com>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Frederic Weisbecker <fweisbec@gmail.com>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: Radim <rkrcmar@redhat.com>
>> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
>
> This also nicely fixes up f9c904b7613b ("sched/cputime:
> Fix steal_account_process_tick() to always return jiffies"),
> which relies on a bool function returning a certain number
> of jiffies :)
>
> Reviewed-by: Rik van Riel <riel@redhat.com>
>
> --
> All rights reversed



-- 
Regards,
Wanpeng Li

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#1406821 — Re: [PATCH v3] sched/cputime: add steal time support to full dynticks CPU time accounting

FromPaolo Bonzini <pbonzini@redhat.com>
Date2016-05-25 12:40 +0200
SubjectRe: [PATCH v3] sched/cputime: add steal time support to full dynticks CPU time accounting
Message-ID<rCEoh-8jG-7@gated-at.bofh.it>
In reply to#1406560

On 25/05/2016 04:16, Wanpeng Li wrote:
> Ping Paolo or Peterz.

No need to ping, since Rik reviewed it 7 hours ago so the thread has
gotten a bump in our mailboxes.

And anyway this is the merge window, which is the most annoying time to
get pings and one-patch changes.  I don't mind at all getting large
series during the merge window, but the small ones definitely can wait a
week or two.

Thanks,

Paolo

> 2016-05-25 3:22 GMT+08:00 Rik van Riel <riel@redhat.com>:
>> On Wed, 2016-05-18 at 20:27 +0800, Wanpeng Li wrote:
>>> From: Wanpeng Li <wanpeng.li@hotmail.com>
>>>
>>> This patch adds steal guest time support to full dynticks CPU
>>> time accounting. After 'commit ff9a9b4c4334 ("sched, time: Switch
>>> VIRT_CPU_ACCOUNTING_GEN to jiffy granularity")', time is jiffy
>>> based sampling even if it's still listened to ring boundaries, so
>>> steal_account_process_tick() is reused to account how much 'ticks'
>>> are steal time after the last accumulation.
>>>
>>> Suggested-by: Rik van Riel <riel@redhat.com>
>>> Cc: Ingo Molnar <mingo@kernel.org>
>>> Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
>>> Cc: Rik van Riel <riel@redhat.com>
>>> Cc: Thomas Gleixner <tglx@linutronix.de>
>>> Cc: Frederic Weisbecker <fweisbec@gmail.com>
>>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>>> Cc: Radim <rkrcmar@redhat.com>
>>> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
>>
>> This also nicely fixes up f9c904b7613b ("sched/cputime:
>> Fix steal_account_process_tick() to always return jiffies"),
>> which relies on a bool function returning a certain number
>> of jiffies :)
>>
>> Reviewed-by: Rik van Riel <riel@redhat.com>
>>
>> --
>> All rights reversed
> 
> 
>

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