Messages in this thread | | | Subject | Re: [RFC][PATCH 2/6] perf, arch: Rework perf_event_index() | From | Peter Zijlstra <> | Date | Tue, 22 Nov 2011 12:51:50 +0100 |
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On Tue, 2011-11-22 at 11:47 +0000, Will Deacon wrote: > On Tue, Nov 22, 2011 at 11:26:20AM +0000, Peter Zijlstra wrote: > > On Mon, 2011-11-21 at 22:43 +0000, Will Deacon wrote: > > > Perhaps we could disable it while per-cpu events are running, although I > > > think this will probably just lead to SIGILL central for anybody trying to > > > use the counters in userspace. > > > > One possibility would be to do as I did in patch 4, except ARM has it > > disabled by default and the folks who think they know WTF they're doing > > can enable it or so. > > The problem is that everybody thinks they know WTF they're doing!
> But you know that the first thing people will do is zero the registers.
*groan*, fair enough ;-)
> > Also, for those ARMs that do have a user readable clock, you could > > support the new time_{mult,shift,offset} from patch 5. > > The user-readable clock will first appear in Cortex-A15, so the code for > that still needs to hit mainline before I can look at doing this in perf.
OK, I had interpreted your "we don't always have" to be slightly more common than just A15.
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