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[Qemu-devel] [PATCH V2 4/4] kvm_stat: Add RESET support for perf event i
From: |
Wei Huang |
Subject: |
[Qemu-devel] [PATCH V2 4/4] kvm_stat: Add RESET support for perf event ioctl |
Date: |
Fri, 23 Jan 2015 15:44:46 -0500 |
While running kvm_stat using tracepoint on ARM64 hardware (e.g. "kvm_stat
-1 -t"), the initial values of some kvm_userspace_exit counters were found
to be very suspecious. For instance the tracing tool showed that S390_TSCH
was called many times on ARM64 machine, which apparently was wrong.
This patch adds RESET ioctl support for perf monitoring. Before calling
ioctl to enable a perf event, this patch resets the counter first. With
this patch, the init counter values become correct on ARM64 hardware.
Example:
==== before patch ====
kvm_userspace_exit(S390_SIEIC) 1426 0
kvm_userspace_exit(S390_TSCH) 339 0
==== after patch ====
kvm_userspace_exit(S390_SIEIC) 0 0
kvm_userspace_exit(S390_TSCH) 0 0
Signed-off-by: Wei Huang <address@hidden>
---
scripts/kvm/kvm_stat | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/scripts/kvm/kvm_stat b/scripts/kvm/kvm_stat
index 8f6f007..f927e97 100755
--- a/scripts/kvm/kvm_stat
+++ b/scripts/kvm/kvm_stat
@@ -186,6 +186,7 @@ ioctl_numbers = {
'SET_FILTER' : 0x40082406,
'ENABLE' : 0x00002400,
'DISABLE' : 0x00002401,
+ 'RESET' : 0x00002403,
}
def x86_init(flag):
@@ -346,6 +347,9 @@ class Event(object):
def disable(self):
import fcntl
fcntl.ioctl(self.fd, ioctl_numbers['DISABLE'], 0)
+ def reset(self):
+ import fcntl
+ fcntl.ioctl(self.fd, ioctl_numbers['RESET'], 0)
class TracepointProvider(object):
def __init__(self):
@@ -405,6 +409,7 @@ class TracepointProvider(object):
for group in self.group_leaders:
for event in group.events:
if event.name in fields:
+# event.reset()
event.enable()
else:
event.disable()
--
1.8.3.1