Messages in this thread | | | Date | Mon, 7 Dec 2015 15:12:42 +0100 | From | Peter Zijlstra <> | Subject | Re: [tip:perf/core] perf/x86: Use INST_RETIRED.PREC_DIST for cycles: ppp |
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On Mon, Dec 07, 2015 at 11:02:58AM -0300, Arnaldo Carvalho de Melo wrote: > Em Mon, Dec 07, 2015 at 07:48:41AM +0100, Ingo Molnar escreveu: > > * Peter Zijlstra <peterz@infradead.org> wrote: > > > On Sun, Dec 06, 2015 at 02:11:02PM +0100, Ingo Molnar wrote: > > > > Also, I'm not convinced we need a new 'ppp' qualifier for any of this, why not > > > > just replace 'pp' with this event - 'pp' is meant to be our most precise > > > > event. > > > > I requested this because the PREC_DIST events can only be scheduled on a single > > > counter, whereas the existing :pp events can be had on all 4. > > > > This mean you can have 2 concurrent :pp users (without RR), but not :ppp. > > > Ok. Will tooling do the right thing? I.e. will the first user of 'perf top' get > > :ppp automatically, while the second one falls back to :pp? > > I guess so: > > void perf_event_attr__set_max_precise_ip(struct perf_event_attr *attr) > { > attr->precise_ip = 3;
Indeed so, I've since confirmed it does also works in practise.
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