** Description changed:
When running a workload that frequently migrates threads, when cpu usage
shows bogus values.
This is present in 12.04, but not present in 10.10.
It is expected that when running this workload the cpu usage would be
reported correctly.
One can verify this by running:
ps ax -opid,comm,pcpu|grep migration | sort -k3 -rn
+
+ Here is more information about this issue:
+ http://lwn.net/Articles/473172/
** Also affects: linux (Ubuntu Quantal)
Importance: High
Assignee: Chris J Arges (christopherarges)
Status: Confirmed
** Description changed:
+ SRU Justification:
+
+ Impact:
When running a workload that frequently migrates threads, when cpu usage
shows bogus values.
This is present in 12.04, but not present in 10.10.
It is expected that when running this workload the cpu usage would be
reported correctly.
One can verify this by running:
ps ax -opid,comm,pcpu|grep migration | sort -k3 -rn
Here is more information about this issue:
http://lwn.net/Articles/473172/
+
+ Fix:
+ This fix is present in upstream linux with commit:
+ 8f6189684eb4e85e6c593cd710693f09c944450a
+
+ Testcase:
+ Run a workload that frequently migrates threads, then show cpu usage. With
this patch it should show proper usage.
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https://bugs.launchpad.net/bugs/1057593
Title:
kernel migration threads report bogus high cpu usage
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