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

PATCH RESEND In review Laurent Vivier 2 participants 4 messages Sep 10, 2007 Scheduler

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Laurent Vivier

author

2007-09-10 14:14 UTC #0 lore raw

PATCH RESEND 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 <[email protected]>

Signature · 2 lines

------------- [email protected]  --------------
          "Software is hard" - Donald Knuth

include/linux/sched.h +1 -0

Index: linux-2.6/include/linux/sched.h
===================================================================
@@ -1316,6 +1316,7 @@ 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 +25 -0

Index: linux-2.6/kernel/sched.c
===================================================================
@@ -3277,6 +3277,25 @@ void account_user_time(struct task_struc
 }
 
 /*
+ * Account guest cpu time to a process.
+ * @p: the process that the cpu time gets accounted to
+ * @cputime: the cpu time spent in virtual machine since the last update
+ */
+void account_guest_time(struct task_struct *p, cputime_t cputime)
+{
+	cputime64_t tmp;
+	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
+
+	tmp = cputime_to_cputime64(cputime);
+
+	p->utime = cputime_add(p->utime, cputime);
+	p->gtime = cputime_add(p->gtime, cputime);
+
+	cpustat->user = cputime64_add(cpustat->user, tmp);
+	cpustat->guest = cputime64_add(cpustat->guest, tmp);
+}
+
+/*
  * Account system cpu time to a process.
  * @p: the process that the cpu time gets accounted to
  * @hardirq_offset: the offset to subtract from hardirq_count()

@@ -3289,6 +3308,12 @@ void account_system_time(struct task_str
 	struct rq *rq = this_rq();
 	cputime64_t tmp;
 
+	if (p->flags & PF_VCPU) {
+		account_guest_time(p, cputime);
+		p->flags &= ~PF_VCPU;
+		return;
+	}
+
 	p->stime = cputime_add(p->stime, cputime);
 
 	/* Add system time to cpustat. */

Randy Dunlap

2007-09-10 15:55 UTC #1 lore raw

Quoted 9 lines · On Mon, 10 Sep 2007 16:12:58 +0200 Laurent Vivier wrote:

[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 <[email protected]>

Hi,
Please use kernel-doc notation here:
(see Documentation/kernel-doc-nano-HOWTO.txt or source file examples or ask)

easy fix:

/*
+ * Account guest cpu time to a process.

/**
* account_guest_time - Account guest cpu time to a process.

+ * @p: the process that the cpu time gets accounted to
+ * @cputime: the cpu time spent in virtual machine since the last update
+ */
+void account_guest_time(struct task_struct *p, cputime_t cputime) +{

Thanks.
---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***

Laurent Vivier

author

2007-09-10 16:02 UTC #2 lore raw

Quoted 29 lines · Randy Dunlap

Quoted 9 lines · On Mon, 10 Sep 2007 16:12:58 +0200 Laurent Vivier wrote:
[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 <[email protected]>
Hi,
Please use kernel-doc notation here:
(see Documentation/kernel-doc-nano-HOWTO.txt or source file examples or ask)
easy fix:
/*
+ * Account guest cpu time to a process.
/**
* account_guest_time - Account guest cpu time to a process.
+ * @p: the process that the cpu time gets accounted to
+ * @cputime: the cpu time spent in virtual machine since the last update
+ */

kernel/sched.c void account_user_time(struct task_struc · line 3285

Quoted 2 lines

kernel/sched.c +2 -0

+void account_guest_time(struct task_struct *p, cputime_t cputime)
+{

thank you for the comment.

But I just made a cut&past of the comment of the function above.

Should I be consistent with the doc or with the source ?

Laurent

Signature · 2 lines

------------- [email protected]  --------------
          "Software is hard" - Donald Knuth

Randy Dunlap

2007-09-10 16:16 UTC #3 lore raw

Quoted 35 lines · On Mon, 10 Sep 2007 18:01:34 +0200 Laurent Vivier wrote:

Quoted 29 lines · Randy Dunlap
Quoted 9 lines · On Mon, 10 Sep 2007 16:12:58 +0200 Laurent Vivier wrote:
[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 <[email protected]>
Hi,
Please use kernel-doc notation here:
(see Documentation/kernel-doc-nano-HOWTO.txt or source file examples or ask)
easy fix:
/*
+ * Account guest cpu time to a process.
/**
* account_guest_time - Account guest cpu time to a process.
+ * @p: the process that the cpu time gets accounted to
+ * @cputime: the cpu time spent in virtual machine since the last update
+ */
kernel/sched.c void account_user_time(struct task_struc · line 3285
Quoted 2 lines
kernel/sched.c +2 -0
+void account_guest_time(struct task_struct *p, cputime_t cputime)
+{
thank you for the comment.

Quoted 3 lines

But I just made a cut&past of the comment of the function above.
Should I be consistent with the doc or with the source ?

I see. That entire file could use some kernel-doc-ization.

I suppose that lessens the need for you to make such a change. I'll probably do it some slow night then.

Thanks,
---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***