Messages in this thread | | | Subject | Re: [RFC][PATCH] perf: sysfs type id | From | Peter Zijlstra <> | Date | Wed, 17 Nov 2010 20:57:14 +0100 |
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On Wed, 2010-11-17 at 11:47 -0800, Corey Ashford wrote: > > This is an interesting approach, though for the IBM WSP (aka PowerEN) > chip, the config_format would have to be at a deeper level than the PMU, > because the modifiers that affect the event, vary from event to event. > Either that or you'd have to provide a complex union structure.
Eew.. how uhm creative ;-), yeah, not quite sure how to deal with that, I wasn't planning to make a directory for each event, just a single file with the u64 in it.
> However, above you say that you want to have "a few frequently > used/common events". I thought that was the job of the perf "generic > events". My understanding was that the sysfs tree was the solution for > all events, including arch-specific, and seldom-used events.
My intent for the sysfs bits is to replace all the static stuff encoded in PERF_TYPE_ and PERF_COUNT_ because it simply doesn't extend to a much more dynamic world.
And GPUs/DSPs might have radically different common events than CPUs do.
Doing exhaustive lists in sysfs is simply going to waste tons of memory for no real gain.
> Ingo > pushed back on a user-space library solution (like libpfm4) because he > wanted event info in sysfs (or some other mechanism by which the kernel > could expose event info to user space).
I can't fully remember the details of that discussion.
> If there is going to be no place in sysfs for arch-specific events, I'll > want to start pushing for perf to be able to use a user space library again. > > How about a compromise position: all of the arch-specific events are > exposed to user space via sysfs iff some CONFIG_* variable to set to > true. Something like CONFIG_EXPOSE_ALL_HW_PERF_EVENTS_IN_SYSFS. > This way you would only use all that memory when it's explicitly > configured in.
Ingo, any opinions?
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