From 763952d08b9c89726151a72f90bca90d0828302d Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Tue, 17 Jun 2014 17:54:30 +1000 Subject: [PATCH] kvm_stat: Only consider online cpus 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 Signed-off-by: Paolo Bonzini --- 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 d7e97e7488..2a788bc34c 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