[PATCH v2] sched/cputime: add steal time support to full dynticks CPU time accounting

[PATCH v2] sched/cputime: add steal time support to full dynticks CPU time accounting

[Wanpeng Li]

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>
---
v1 -> v2:
 * fix divide zero bug, thanks Rik

 kernel/sched/cputime.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 75f98c5..bfa50a0 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 +691,12 @@ static cputime_t get_vtime_delta(struct task_struct *tsk)
 
 static void __vtime_account_system(struct task_struct *tsk)
 {
+	unsigned long steal_time = steal_account_process_tick();
 	cputime_t delta_cpu = get_vtime_delta(tsk);
 
+	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 +727,12 @@ void vtime_account_user(struct task_struct *tsk)
 	write_seqcount_begin(&tsk->vtime_seqcount);
 	tsk->vtime_snap_whence = VTIME_SYS;
 	if (vtime_delta(tsk)) {
+		unsigned long steal_time = steal_account_process_tick();
 		delta_cpu = get_vtime_delta(tsk);
+
+		if (steal_time >= delta_cpu)
+			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

Re: [PATCH v2] sched/cputime: add steal time support to full dynticks CPU time accounting

[Mika Penttilä]

On 05/18/2016 11:28 AM, 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>
> ---
> v1 -> v2:
>  * fix divide zero bug, thanks Rik
> 
>  kernel/sched/cputime.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
> index 75f98c5..bfa50a0 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 +691,12 @@ static cputime_t get_vtime_delta(struct task_struct *tsk)
>  
>  static void __vtime_account_system(struct task_struct *tsk)
>  {
> +	unsigned long steal_time = steal_account_process_tick();
>  	cputime_t delta_cpu = get_vtime_delta(tsk);
>  
> +	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 +727,12 @@ void vtime_account_user(struct task_struct *tsk)
>  	write_seqcount_begin(&tsk->vtime_seqcount);
>  	tsk->vtime_snap_whence = VTIME_SYS;
>  	if (vtime_delta(tsk)) {
> +		unsigned long steal_time = steal_account_process_tick();
>  		delta_cpu = get_vtime_delta(tsk);


afaik steal_account_process_tick() returns jiffies and get_vtime_delta() cputime, so can't mix them like this : ?

> +
> +		if (steal_time >= delta_cpu)
> +			return;



> +		delta_cpu -= steal_time;
>  		account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
>  	}
>  	write_seqcount_end(&tsk->vtime_seqcount);
> 


--Mika

Re: [PATCH v2] sched/cputime: add steal time support to full dynticks CPU time accounting

[Wanpeng Li]

2016-05-18 17:46 GMT+08:00 Mika Penttilä <mika.penttila@nextfour.com>:
> On 05/18/2016 11:28 AM, 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>
>> ---
>> v1 -> v2:
>>  * fix divide zero bug, thanks Rik
>>
>>  kernel/sched/cputime.c | 13 +++++++++++--
>>  1 file changed, 11 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
>> index 75f98c5..bfa50a0 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 +691,12 @@ static cputime_t get_vtime_delta(struct task_struct *tsk)
>>
>>  static void __vtime_account_system(struct task_struct *tsk)
>>  {
>> +     unsigned long steal_time = steal_account_process_tick();
>>       cputime_t delta_cpu = get_vtime_delta(tsk);
>>
>> +     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 +727,12 @@ void vtime_account_user(struct task_struct *tsk)
>>       write_seqcount_begin(&tsk->vtime_seqcount);
>>       tsk->vtime_snap_whence = VTIME_SYS;
>>       if (vtime_delta(tsk)) {
>> +             unsigned long steal_time = steal_account_process_tick();
>>               delta_cpu = get_vtime_delta(tsk);
>
>
> afaik steal_account_process_tick() returns jiffies and get_vtime_delta() cputime, so can't mix them like this : ?

You are right, thanks for your review. I will fix it.

Regards,
Wanpeng Li