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From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: "Wanpeng Li" <wanpeng.li@hotmail.com>,
	"Ingo Molnar" <mingo@kernel.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	"Rik van Riel" <riel@redhat.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Frederic Weisbecker" <fweisbec@gmail.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>
Subject: [PATCH v5 3/3] sched/cputime: Add steal time support to full dynticks CPU time accounting
Date: Wed,  8 Jun 2016 11:05:10 +0800	[thread overview]
Message-ID: <1465355110-21714-3-git-send-email-wanpeng.li@hotmail.com> (raw)
In-Reply-To: <1465355110-21714-1-git-send-email-wanpeng.li@hotmail.com>

From: Wanpeng Li <wanpeng.li@hotmail.com>

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 listened
to ring boundaries, so steal_account_process_tick() is reused
to account how many 'ticks' are stolen-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 Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
v4 -> v5:
 * apply same logic to account_idle_time, so change get_vtime_delta instead
v3 -> v4:
 * fix grammar errors, thanks Ingo
 * cleanup fragile codes, thanks Ingo
v2 -> v3:
 * convert steal time jiffies to cputime
v1 -> v2:
 * fix divide zero bug, thanks Rik

 kernel/sched/cputime.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 75f98c5..b62f9f8 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;
 }
 
 /*
@@ -681,12 +681,17 @@ 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;
+	cputime_t delta_time, steal_time;
 
+	steal_time = jiffies_to_cputime(steal_account_process_tick());
+	delta_time = jiffies_to_cputime(now - tsk->vtime_snap);
 	WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE);
 	tsk->vtime_snap = now;
 
-	return jiffies_to_cputime(delta);
+	if (steal_time < delta_time)
+		delta_time -= steal_time;
+
+	return delta_time;
 }
 
 static void __vtime_account_system(struct task_struct *tsk)
-- 
1.9.1

  parent reply	other threads:[~2016-06-08  3:06 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-08  3:05 [PATCH v5 1/3] KVM: fix steal clock warp during guest cpu hotplug Wanpeng Li
2016-06-08  3:05 ` [PATCH v5 2/3] sched/cputime: Fix prev steal time accouting during " Wanpeng Li
2016-06-08 10:01   ` Paolo Bonzini
2016-06-08 10:59     ` Wanpeng Li
2016-06-08  3:05 ` Wanpeng Li [this message]
2016-06-08  7:22   ` [PATCH v5 3/3] sched/cputime: Add steal time support to full dynticks CPU time accounting Ingo Molnar
2016-06-08  7:27     ` Wanpeng Li
2016-06-08  7:52       ` Ingo Molnar
2016-06-08  8:04         ` Wanpeng Li
2016-06-08  8:12           ` Wanpeng Li
2016-06-08 10:14   ` Paolo Bonzini
2016-06-08 11:11     ` Wanpeng Li
2016-06-13  3:38     ` Wanpeng Li
2016-06-13  7:55       ` Paolo Bonzini
2016-06-13  8:09         ` Wanpeng Li
2016-06-08 19:05   ` Rik van Riel
2016-06-08 23:57     ` Wanpeng Li
2016-06-09  1:20       ` Rik van Riel

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