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[15/16] KVM-GST: KVM Steal time accounting

Message ID 1295892397-11354-16-git-send-email-glommer@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Glauber Costa Jan. 24, 2011, 6:06 p.m. UTC
None
diff mbox

Patch

diff --git a/kernel/sched.c b/kernel/sched.c
index ea3e5ef..3b3e88d 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3508,6 +3508,38 @@  unsigned long long thread_group_sched_runtime(struct task_struct *p)
 	return ns;
 }
 
+cputime_t (*hypervisor_steal_time)(void) = NULL;
+
+/*
+ * We have to at flush steal time information every time something else
+ * is accounted. Since the accounting functions are all visible to the rest
+ * of the kernel, it gets tricky to do them in one place. This helper function
+ * helps us.
+ *
+ * When the system is idle, the concept of steal time does not apply. We just
+ * tell the underlying hypervisor that we grabbed the data, but skip steal time
+ * accounting
+ */
+static int touch_steal_time(int is_idle)
+{
+	u64 steal;
+	struct rq *rq = this_rq();
+
+	if (!hypervisor_steal_time)
+		return 0;
+
+	steal = hypervisor_steal_time();
+
+	if (is_idle)
+		return 0;
+
+	if (steal) {
+		account_steal_time(steal);
+		return 1;
+	}
+	return 0;
+}
+
 /*
  * Account user cpu time to a process.
  * @p: the process that the cpu time gets accounted to
@@ -3520,6 +3552,9 @@  void account_user_time(struct task_struct *p, cputime_t cputime,
 	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
 	cputime64_t tmp;
 
+	if (touch_steal_time(0))
+		return;
+
 	/* Add user time to process. */
 	p->utime = cputime_add(p->utime, cputime);
 	p->utimescaled = cputime_add(p->utimescaled, cputime_scaled);
@@ -3580,6 +3615,9 @@  void account_system_time(struct task_struct *p, int hardirq_offset,
 	struct cpu_usage_stat *cpustat = &kstat_this_cpu.cpustat;
 	cputime64_t tmp;
 
+	if (touch_steal_time(0))
+		return;
+
 	if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
 		account_guest_time(p, cputime, cputime_scaled);
 		return;
@@ -3627,6 +3665,8 @@  void account_idle_time(cputime_t cputime)
 	cputime64_t cputime64 = cputime_to_cputime64(cputime);
 	struct rq *rq = this_rq();
 
+	touch_steal_time(1);
+
 	if (atomic_read(&rq->nr_iowait) > 0)
 		cpustat->iowait = cputime64_add(cpustat->iowait, cputime64);
 	else