On Tue, Nov 10, 2020 at 02:52:43PM +0800, Leo Yan wrote:
Hi all,
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On the mainlne kernel with the latest commit 407ab579637c "Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm", the perf cs-etm testing fails.
I found the perf cs-etm testing itself has a typo issue and a regression introduced by Perf tool in the recent mainline kernel, so I sent out the two patches for fixing the related issues [1].
Even after applying these two fixings for the testing script, I still observe the etm testing failure with snapshot mode. I manully checked the perf data and confirmed the perf data contains the raw trace data for snapshot (so 'perf script -D' can work well), but it fails to generate any branch samples, so the command 'perf script' will not output any samples.
Seems to me, this issue is more likely related with driver or Perf tool's common code change but not the testing itself;
If the trace data is available then it is likely the kernel drivers worked properly. I would concentrate on the perf tools - with the amount of code churn in that subsystem many regressions have been introduced before.
to use 'git bisect' to narrow down the snapshot mode failure, if you have any idea for fixing this issue, please let me know. Otherwise, I will dig into this issue and keep posted.
I'm afraid a bisect is your only option.
Thanks for looking into this, Mathieu
Thanks, Leo