Messages in this thread | | | Date | Mon, 11 May 2009 11:29:39 +1000 | From | Paul Mackerras <> | Subject | Re: [PATCH 3/5] perf_counter: rework ioctl()s |
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Peter Zijlstra writes:
> Corey noticed that ioctl()s on grouped counters didn't work on the whole group. > This extends the ioctl() interface to take a second argument that is > interpreted as a flags field. We then provide PERF_IOC_FLAG_GROUP to toggle > the behaviour. > > Having this flag gives the greatest flexibility, allowing you to individually > enable/disable/reset counters in a group, or all together.
As far as enable/disable are concerned, I don't think this is really necessary. My intention was that if you want to enable/disable a whole group you just enable/disable the leader and leave all its siblings enabled, since if the leader is disabled the whole group can't go on.
Corey's problem was that we have a bug where enabling the leader only puts the leader on and not the enabled group members. I meant to send a patch to fix that ages ago but I got distracted. I'll send out the patch shortly.
Paul.
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