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* [Qemu-devel] [PATCH 1/6] kvm_stat: Only consider online cpus
@ 2014-06-17  7:54 Michael Ellerman
  2014-06-17  7:54 ` [Qemu-devel] [PATCH 2/6] kvm_stat: Fix the non-x86 exit reasons Michael Ellerman
                   ` (4 more replies)
  0 siblings, 5 replies; 14+ messages in thread
From: Michael Ellerman @ 2014-06-17  7:54 UTC (permalink / raw)
  To: qemu-devel; +Cc: kvm, aik, jan.kiszka, agraf, jfrei, alfs, pbonzini

In kvm_stat we grovel through /sys to find out how many cpus are in the
system. However if a cpu is offline it will still be present in /sys,
and the perf_event_open() will fail.

Modify the logic to only return online cpus. We need to be careful on
systems which don't support cpu hotplug, the online file will not be
present at all.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 scripts/kvm/kvm_stat | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/scripts/kvm/kvm_stat b/scripts/kvm/kvm_stat
index d7e97e7..2a788bc 100755
--- a/scripts/kvm/kvm_stat
+++ b/scripts/kvm/kvm_stat
@@ -311,18 +311,30 @@ class TracepointProvider(object):
         self.select(fields)
     def fields(self):
         return self._fields
+
+    def _online_cpus(self):
+        l = []
+        pattern = r'cpu([0-9]+)'
+        basedir = '/sys/devices/system/cpu'
+        for entry in os.listdir(basedir):
+            match = re.match(pattern, entry)
+            if not match:
+                continue
+            path = os.path.join(basedir, entry, 'online')
+            if os.path.exists(path) and open(path).read().strip() != '1':
+                continue
+            l.append(int(match.group(1)))
+        return l
+
     def _setup(self, _fields):
         self._fields = _fields
-        cpure = r'cpu([0-9]+)'
-        self.cpus = [int(re.match(cpure, x).group(1))
-                     for x in os.listdir('/sys/devices/system/cpu')
-                     if re.match(cpure, x)]
+        cpus = self._online_cpus()
         import resource
-        nfiles = len(self.cpus) * 1000
+        nfiles = len(cpus) * 1000
         resource.setrlimit(resource.RLIMIT_NOFILE, (nfiles, nfiles))
         events = []
         self.group_leaders = []
-        for cpu in self.cpus:
+        for cpu in cpus:
             group = Group(cpu)
             for name in _fields:
                 tracepoint = name
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 14+ messages in thread

end of thread, other threads:[~2014-11-03  0:40 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2014-06-17  7:54 [Qemu-devel] [PATCH 1/6] kvm_stat: Only consider online cpus Michael Ellerman
2014-06-17  7:54 ` [Qemu-devel] [PATCH 2/6] kvm_stat: Fix the non-x86 exit reasons Michael Ellerman
2014-10-31 15:49   ` Paolo Bonzini
2014-06-17  7:54 ` [Qemu-devel] [PATCH 3/6] kvm_stat: Rework platform detection Michael Ellerman
2014-06-17  7:54 ` [Qemu-devel] [PATCH 4/6] kvm_stat: Fix tracepoint filter definition for s390 Michael Ellerman
2014-06-17  7:54 ` [Qemu-devel] [PATCH 5/6] kvm_stat: Abstract ioctl numbers Michael Ellerman
2014-06-17  7:54 ` [Qemu-devel] [PATCH 6/6] kvm_stat: Add powerpc support Michael Ellerman
2014-06-17  8:27   ` Alexander Graf
2014-06-18  0:50     ` Michael Ellerman
2014-06-18  0:59       ` Alexander Graf
2014-06-18  1:37         ` Michael Ellerman
2014-06-18  1:54           ` Alexander Graf
2014-10-31 15:36   ` Paolo Bonzini
2014-11-03  0:40     ` Michael Ellerman

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