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cpu: Update checking if EPB is supported

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Update checking if EPB is supported so that it works with recent
versions of the x86_energy_perf_policy tool. Newer versions of
x86_energy_perf_policy, unlike older versions, exit with a zero exit
code even if the CPU doesn't support EPB. Newer versions of the tool
give no ouput on stdout if EPB is not supported, so check for that.

In the future, we might like to determine if EPB is supported by
searching /proc/cpuinfo for specific CPU flags. However the solution
described in the previous paragraph should work just fine for now.

Resolves: rhbz#1690929

Signed-off-by: Ondřej Lysoněk <olysonek@redhat.com>
This commit is contained in:
Ondřej Lysoněk 2019-11-22 14:09:02 +01:00
parent 3792d6320f
commit 43375e6bbe
1 changed files with 5 additions and 2 deletions
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7
tuned/plugins/plugin_cpu.py
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@ -93,8 +93,11 @@ class CPULatencyPlugin(base.Plugin):
def _check_energy_perf_bias(self):
self._has_energy_perf_bias = False
retcode_unsupported = 1
retcode = self._cmd.execute(["x86_energy_perf_policy", "-r"], no_errors = [errno.ENOENT, retcode_unsupported])[0]
if retcode == 0:
retcode, out = self._cmd.execute(["x86_energy_perf_policy", "-r"], no_errors = [errno.ENOENT, retcode_unsupported])
# With recent versions of the tool, a zero exit code is
# returned even if EPB is not supported. The output is empty
# in that case, however.
if retcode == 0 and out != "":
self._has_energy_perf_bias = True
elif retcode < 0:
log.warning("unable to run x86_energy_perf_policy tool, ignoring CPU energy performance bias, is the tool installed?")