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SubjectRe: [RFC][PATCH] perf: Rewrite core context handling
On Tue, Oct 16, 2018 at 04:34:05PM +0000, Song Liu wrote:
> >> 3. perf_event_pmu_context owns RB tree of events. Since we don't
> >> need rotation across multiple hardware PMUs, the rotation is
> >> within same perf_event_pmu_context.
> >
> > By keeping the RB trees in perf_event_context, we get bigger trees,
> > which is more efficient (log(n+m) < log(n) + log(m))
> >
> > Also, specifically, it means we only need a single merge sort /
> > iteration to schedule in a full context, instead of (again) doing 'n' of
> > them.
> >
> > Also, given a context and a pmu, it is cheaper for finding the relevant
> > events; this is needed for big.little for instance. Something the
> > proposed patch doesn't fully flesh out.
>
> Would it be faster if we add a perf_event_pmu_context pointer to the
> perf_event?

+ pmu_ctx = find_get_pmu_context(pmu, ctx, event);
+ if (IS_ERR(pmu_ctx)) {
+ err = PTR_ERR(pmu_ctx);
+ goto err_locked;
+ }
+ event->pmu_ctx = pmu_ctx;

Like that?

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