** Changed in: ubuntu-z-systems
Status: Incomplete => Triaged
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https://bugs.launchpad.net/bugs/1828166
Title:
perf top problem on z with Ubuntu 18.04
Status in Ubuntu on IBM z Systems:
Triaged
Status in linux package in Ubuntu:
Confirmed
Status in linux source package in Bionic:
In Progress
Status in linux source package in Cosmic:
Invalid
Bug description:
SRU Justification:
==================
[Impact]
* The perf top tool hangs and shows error messages, like 'Not enough
memory for annotating'
[Fix]
* edeb0c90df3581b821a764052d185df985f8b8dc edeb0c9 "perf tools: Stop
fallbacking to kallsyms for vdso symbols lookup"
[Test Case]
* start a benchmark (mem_alloc, but it doesn't really matter what)
* execute perf top in a second terminal
* the output of perf top is correct
* now stop the benchmark
* and perf top shows an error message, like "Not enough memory for
annotating '__irf_end' symbol!)"
* and perf top can't be exited anymore
[Regression Potential]
* The regression potential can be considered as low since this happens
only while using the perf top tool
* and it is known that the commit (above) fixes the problem
* and the fix is upstream since 4.19
[Other Info]
* current disco and eoan kernels don't show that problem
* bisecting result points to above commit
* applies cleanly on cosmic, but has a little conflict on bionic (both
master-next)
_________________________
perf top hangs and shows error messages
---uname output---
Linux weather 4.15.0-46-generic #49-Ubuntu SMP Wed Feb 6 09:32:27 UTC 2019
s390x s390x s390x GNU/Linux
---Steps to Reproduce---
I start a benchmark (mem_alloc, but it really doesn't matter) and then issue
perf top in a second terminal, the output from perf top is correct. Now I stop
the benchmark: perf top shows a error message (Not enough memory for annotating
'__irf_end' symbol!) and I can't quit from perf top anymore
Following analyse took place:
No problem with current kernel .
Bi-Secting of perf tool took place and following commit was found:
commit edeb0c90df3581b821a764052d185df985f8b8dc (HEAD, refs/bisect/bad)
Author: Arnaldo Carvalho de Melo <[email protected]>
Date: Tue Oct 16 17:08:29 2018 -0300
perf tools: Stop fallbacking to kallsyms for vdso symbols lookup
When you apply this patch the issue is gone, however it is contained
in these versions:
git tag --contains edeb0c90df3581b821
v4.19
v4.20
....
The level I was debugging was kernel 4.15 which does not contain this
patch.
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