[1.0] libct/cg/v1: work around CPU quota period set failure #3115
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As reported in issue 3084, sometimes setting CPU quota period fails when a new period is lower and a parent cgroup has CPU quota limit set. This happens as in cgroup v1 the quota and the period can not be set together (this is fixed in v2), and since the period is being set first, new_limit = old_quota/new_period may be higher than the parent cgroup limit. The fix is to retry setting the period after the quota, to cover all possible scenarios. Add a test case to cover a regression caused by an earlier version of this patch (ignoring a failure of setting invalid period when quota is not set). Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com> (cherry picked from commit 1b77ebe) Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
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AkihiroSuda
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Aug 10, 2021
mrunalp
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Aug 11, 2021
This was referenced Aug 11, 2021
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This is a partial backport of #3090 (first commit -- the fix itself -- only) to release-1.0 branch. Test case and cleanups are omitted as those are too big and do not add much value to this branch.
As reported in issue #3084, sometimes setting CPU quota period fails
when a new period is lower and a parent cgroup has CPU quota limit set.
This happens as in cgroup v1 the quota and the period can not be set
together (this is fixed in v2), and since the period is being set first,
new_limit = old_quota/new_periodmay be higher than the parent cgrouplimit.
The fix is to retry setting the period after the quota, to cover all
possible scenarios.
Add a test case to cover a regression caused by an earlier version of
this patch (ignoring a failure of setting invalid period when quota is
not set).
Signed-off-by: Kir Kolyshkin kolyshkin@gmail.com
(cherry picked from commit 1b77ebe)
Signed-off-by: Kir Kolyshkin kolyshkin@gmail.com
Proposed changelog entry