Re: Mixed group of sw/hw counters are not started if sw counter isgroup leader

[Jiri Olsa]

On Tue, Jan 29, 2013 at 11:56:01AM -0500, Vince Weaver wrote:
> On Tue, 29 Jan 2013, Jiri Olsa wrote:
> 
> > ok, there's been perf fixies wrt enable events groups, but they
> > landed in 3.8-rc1.. until that point all the group members are
> > specifically enabled, so that's why your perf is working and
> > mine not..
> > 
> > Anyway, seems like there's bug in kernel code when we have group
> > with sw and hw counters.
> > 
> > Attached path makes your test case working for me. I'll give it some
> > more thoughts & testing and send it out soon. If you like to test,
> > please go ahead.
> 
> I've added a test to my perf_event_test testsuite to look for this bug.
>    http://www.eece.maine.edu/~vweaver/projects/perf_events/validation/
> 
> In my (minimal) testing so far it looks like this bug does exist in 3.2
> but does not in 2.6.35.  Is anyone curious enough to do a bisect to find 
> out when it was introduced?

I found this started at v2.6.37 where following commit that introduced
the group moving was added:

perf: Complete software pmu grouping
commit b04243ef7006cda301819f54ee7ce0a3632489e3
Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Date:   Fri Sep 17 11:28:48 2010 +0200

I could not get finer bisection within 2.6.37 because the kernel
deadlocked each time I ran the test.

But it seems this problem is there from the introducing
of the group moving.

CCing more folks and lkml

jirka
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