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Subject[PATCH] x86/kvm: Show guest system/user cputime in cpustat
Date
Currently we can only get the cpu_stat of whole guest as one. This patch
enhanced cpu_stat with more detail, has guest_system and guest_user cpu time
statistics with a little overhead.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
---
This draft patch based on KVM upstream to show the idea. I would split it into
more kernel friendly version later.

The overhead is, the cost of get_cpl() after each exit from guest.

Comments are welcome!

arch/x86/kvm/x86.c | 10 ++++++++++
fs/proc/stat.c | 22 ++++++++++++++++------
include/linux/kernel_stat.h | 2 ++
include/linux/kvm_host.h | 1 +
include/linux/sched.h | 1 +
kernel/sched.c | 6 ++++++
6 files changed, 36 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 703f637..c8ea6e1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4290,6 +4290,14 @@ static void inject_pending_event(struct kvm_vcpu *vcpu)
}
}

+static void kvm_update_guest_mode(struct kvm_vcpu *vcpu)
+{
+ int cpl = kvm_x86_ops->get_cpl(vcpu);
+
+ if (cpl != 0)
+ current->flags |= PF_VCPU_USER;
+}
+
static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
{
int r;
@@ -4377,6 +4385,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
trace_kvm_entry(vcpu->vcpu_id);
kvm_x86_ops->run(vcpu);

+ kvm_update_guest_mode(vcpu);
+
/*
* If the guest has used debug registers, at least dr7
* will be disabled while returning to the host.
diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index b9b7aad..d07640a 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -27,7 +27,7 @@ static int show_stat(struct seq_file *p, void *v)
int i, j;
unsigned long jif;
cputime64_t user, nice, system, idle, iowait, irq, softirq, steal;
- cputime64_t guest, guest_nice;
+ cputime64_t guest, guest_nice, guest_user, guest_system;
u64 sum = 0;
u64 sum_softirq = 0;
unsigned int per_softirq_sums[NR_SOFTIRQS] = {0};
@@ -36,7 +36,7 @@ static int show_stat(struct seq_file *p, void *v)

user = nice = system = idle = iowait =
irq = softirq = steal = cputime64_zero;
- guest = guest_nice = cputime64_zero;
+ guest = guest_nice = guest_user = guest_system = cputime64_zero;
getboottime(&boottime);
jif = boottime.tv_sec;

@@ -53,6 +53,10 @@ static int show_stat(struct seq_file *p, void *v)
guest = cputime64_add(guest, kstat_cpu(i).cpustat.guest);
guest_nice = cputime64_add(guest_nice,
kstat_cpu(i).cpustat.guest_nice);
+ guest_user = cputime64_add(guest_user,
+ kstat_cpu(i).cpustat.guest_user);
+ guest_system = cputime64_add(guest_system,
+ kstat_cpu(i).cpustat.guest_system);
for_each_irq_nr(j) {
sum += kstat_irqs_cpu(j, i);
}
@@ -68,7 +72,7 @@ static int show_stat(struct seq_file *p, void *v)
sum += arch_irq_stat();

seq_printf(p, "cpu %llu %llu %llu %llu %llu %llu %llu %llu %llu "
- "%llu\n",
+ "%llu %llu %llu\n",
(unsigned long long)cputime64_to_clock_t(user),
(unsigned long long)cputime64_to_clock_t(nice),
(unsigned long long)cputime64_to_clock_t(system),
@@ -78,7 +82,9 @@ static int show_stat(struct seq_file *p, void *v)
(unsigned long long)cputime64_to_clock_t(softirq),
(unsigned long long)cputime64_to_clock_t(steal),
(unsigned long long)cputime64_to_clock_t(guest),
- (unsigned long long)cputime64_to_clock_t(guest_nice));
+ (unsigned long long)cputime64_to_clock_t(guest_nice),
+ (unsigned long long)cputime64_to_clock_t(guest_user),
+ (unsigned long long)cputime64_to_clock_t(guest_system));
for_each_online_cpu(i) {

/* Copy values here to work around gcc-2.95.3, gcc-2.96 */
@@ -93,9 +99,11 @@ static int show_stat(struct seq_file *p, void *v)
steal = kstat_cpu(i).cpustat.steal;
guest = kstat_cpu(i).cpustat.guest;
guest_nice = kstat_cpu(i).cpustat.guest_nice;
+ guest_user = kstat_cpu(i).cpustat.guest_user;
+ guest_system = kstat_cpu(i).cpustat.guest_system;
seq_printf(p,
"cpu%d %llu %llu %llu %llu %llu %llu %llu %llu %llu "
- "%llu\n",
+ "%llu %llu %llu\n",
i,
(unsigned long long)cputime64_to_clock_t(user),
(unsigned long long)cputime64_to_clock_t(nice),
@@ -106,7 +114,9 @@ static int show_stat(struct seq_file *p, void *v)
(unsigned long long)cputime64_to_clock_t(softirq),
(unsigned long long)cputime64_to_clock_t(steal),
(unsigned long long)cputime64_to_clock_t(guest),
- (unsigned long long)cputime64_to_clock_t(guest_nice));
+ (unsigned long long)cputime64_to_clock_t(guest_nice),
+ (unsigned long long)cputime64_to_clock_t(guest_user),
+ (unsigned long long)cputime64_to_clock_t(guest_system));
}
seq_printf(p, "intr %llu", (unsigned long long)sum);

diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index c059044..e43b2f7 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -26,6 +26,8 @@ struct cpu_usage_stat {
cputime64_t steal;
cputime64_t guest;
cputime64_t guest_nice;
+ cputime64_t guest_user;
+ cputime64_t guest_system;
};

struct kernel_stat {
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a3fd0f9..497e795 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -496,6 +496,7 @@ static inline void kvm_guest_exit(void)
{
account_system_vtime(current);
current->flags &= ~PF_VCPU;
+ current->flags &= ~PF_VCPU_USER;
}

static inline gpa_t gfn_to_gpa(gfn_t gfn)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 78efe7c..49bf81d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1759,6 +1759,7 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *
#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_VCPU_USER 0x00000020 /* I'm a virtual CPU in usermode */
#define PF_FORKNOEXEC 0x00000040 /* forked but didn't exec */
#define PF_MCE_PROCESS 0x00000080 /* process policy on mce errors */
#define PF_SUPERPRIV 0x00000100 /* used super-user privileges */
diff --git a/kernel/sched.c b/kernel/sched.c
index 3a8fb30..9cfc288 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5092,6 +5092,12 @@ static void account_guest_time(struct task_struct *p, cputime_t cputime,
} else {
cpustat->user = cputime64_add(cpustat->user, tmp);
cpustat->guest = cputime64_add(cpustat->guest, tmp);
+ if (p->flags & PF_VCPU_USER)
+ cpustat->guest_user =
+ cputime64_add(cpustat->guest_user, tmp);
+ else
+ cpustat->guest_system =
+ cputime64_add(cpustat->guest_system, tmp);
}
}

--
1.7.0.1


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