Messages in this thread | | | Date | Tue, 3 Oct 2023 18:33:00 +0200 | From | Peter Zijlstra <> | Subject | Re: [RESEND PATCH V3 1/6] perf: Add branch stack extra |
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On Tue, Oct 03, 2023 at 08:06:59AM -0700, Andi Kleen wrote: > > I'm thinking we should do something like expose branch_counter_nr and > > branch_counter_width in the sysfs node, and then rename this extra field > > to counters. > > > > Then userspace can do something like: > > > > for (i = 0; i < branch_counter_nr; i++) { > > counter[i] = counters & ((1 << branch_counter_width) - 1); > > counters >>= branch_counter_width; > > } > > > > to extract the actual counter values. > > perf script/report won't necessarily have access to the sysfs > values if they run on a different system > > It would need extra PT style metadata written by perf record to > perf.data and read by the user tools. > > Seems complicated. It would be better if it just parsed on its own.
Well, you really don't want to repeat the 4,2 thing in every event, that seems daft (and a waste of space, because how large do we want those fields to be etc..).
We don't really have a better place for these sorts of things. And yeah, the PT thing sets precedent here.
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