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modify account_system_time() to update guest time in cpustat and task_struct

PATCH Superseded Laurent Vivier 1 participant 1 message Aug 20, 2007

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Laurent Vivier

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PATCH 3/4 modify account_system_time() to update guest time in cpustat and task_struct

[PATCH 3/4] modify account_system_time() to add cputime to cpustat->guest if we are running a VCPU. We add this cputime to cpustat->user instead of cpustat->system because this part of KVM code is in fact user code although it is executed in the kernel. We duplicate VCPU time between guest and user to allow an unmodified "top(1)" to display correct value. A modified "top(1)" is able to display good cpu user time and cpu guest time by subtracting cpu guest time from cpu user time. Update "gtime" in task_struct accordingly.

Signed-off-by Laurent Vivier <Laurent.Vivier-6ktuUTfB/[email protected]>
Signature · 2 lines
------------- Laurent.Vivier-6ktuUTfB/[email protected]  --------------
          "Software is hard" - Donald Knuth
include/linux/sched.h +1 -0
Index: kvm/include/linux/sched.h
===================================================================
@@ -1317,6 +1317,7 @@ static inline void put_task_struct(struc
 #define PF_STARTING	0x00000002	/* being created */
 #define PF_EXITING	0x00000004	/* getting shut down */
 #define PF_EXITPIDONE	0x00000008	/* pi exit done on shut down */
+#define PF_VCPU		0x00000010	/* I'm a virtual CPU */
 #define PF_FORKNOEXEC	0x00000040	/* forked but didn't exec */
 #define PF_SUPERPRIV	0x00000100	/* used super-user privileges */
 #define PF_DUMPCORE	0x00000200	/* dumped core */
kernel/sched.c +15 -1
Index: kvm/kernel/sched.c
===================================================================
@@ -3246,10 +3246,24 @@ void account_system_time(struct task_str
 	struct rq *rq = this_rq();
 	cputime64_t tmp;
 
+	tmp = cputime_to_cputime64(cputime);
+#ifdef CONFIG_GUEST_ACCOUNTING
+	if (p->flags & PF_VCPU) {
+		p->utime = cputime_add(p->utime, cputime);
+		p->gtime = cputime_add(p->gtime, cputime);
+
+		cpustat->guest = cputime64_add(cpustat->guest, tmp);
+		cpustat->user = cputime64_add(cpustat->user, tmp);
+
+		p->flags &= ~PF_VCPU;
+
+		return;
+	}
+#endif
+
 	p->stime = cputime_add(p->stime, cputime);
 
 	/* Add system time to cpustat. */
-	tmp = cputime_to_cputime64(cputime);
 	if (hardirq_count() - hardirq_offset)
 		cpustat->irq = cputime64_add(cpustat->irq, tmp);
 	else if (softirq_count())

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