Messages in this thread | | | Date | Fri, 29 Jun 2018 14:27:25 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH v3 4/7] arm_pmu: Tidy up clear_event_idx call backs |
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On Tue, Jun 19, 2018 at 11:15:39AM +0100, Suzuki K Poulose wrote: > The armpmu uses get_event_idx callback to allocate an event > counter for a given event, which marks the selected counter > as "used". Now, when we delete the counter, the arm_pmu goes > ahead and clears the "used" bit and then invokes the "clear_event_idx" > call back, which kind of splits the job between the core code > and the backend. Tidy this up by relying on the clear_event_idx > to do the book keeping, if available. Otherwise, let the core > driver do the default "clear" bit operation. This will be useful > for adding the chained event support, where we leave the event > idx maintenance to the backend. > > Also, when an event is removed from the PMU, reset the hw.idx > to indicate that a counter is not allocated for this event, > to help the backends do better checks. This will be also used > for the chain counter support. > > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Reviewed-by: Julien Thierry <julien.thierry@arm.com> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
TBH, I think it might be better to make clear_event_idx() mandatory, such that each backend provides both clear / set, next to each other in the code.
It's a bit more code, but it would restore orthogonality to the API.
Mark.
> --- > Changes since v2: > - Reset the event counter after an event is removed. > --- > arch/arm/kernel/perf_event_v7.c | 2 ++ > drivers/perf/arm_pmu.c | 17 +++++++++++++---- > 2 files changed, 15 insertions(+), 4 deletions(-) > > diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c > index fd7ce01..765d265 100644 > --- a/arch/arm/kernel/perf_event_v7.c > +++ b/arch/arm/kernel/perf_event_v7.c > @@ -1637,6 +1637,7 @@ static void krait_pmu_clear_event_idx(struct pmu_hw_events *cpuc, > bool venum_event = EVENT_VENUM(hwc->config_base); > bool krait_event = EVENT_CPU(hwc->config_base); > > + clear_bit(hwc->idx, cpuc->used_mask); > if (venum_event || krait_event) { > bit = krait_event_to_bit(event, region, group); > clear_bit(bit, cpuc->used_mask); > @@ -1966,6 +1967,7 @@ static void scorpion_pmu_clear_event_idx(struct pmu_hw_events *cpuc, > bool venum_event = EVENT_VENUM(hwc->config_base); > bool scorpion_event = EVENT_CPU(hwc->config_base); > > + clear_bit(hwc->idx, cpuc->used_mask); > if (venum_event || scorpion_event) { > bit = scorpion_event_to_bit(event, region, group); > clear_bit(bit, cpuc->used_mask); > diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c > index e3766a8..6e10e8c 100644 > --- a/drivers/perf/arm_pmu.c > +++ b/drivers/perf/arm_pmu.c > @@ -227,6 +227,16 @@ static void armpmu_start(struct perf_event *event, int flags) > armpmu->enable(event); > } > > +static void armpmu_clear_event_idx(struct arm_pmu *armpmu, > + struct pmu_hw_events *hw_events, > + struct perf_event *event) > +{ > + if (armpmu->clear_event_idx) > + armpmu->clear_event_idx(hw_events, event); > + else > + clear_bit(event->hw.idx, hw_events->used_mask); > +} > + > static void > armpmu_del(struct perf_event *event, int flags) > { > @@ -237,11 +247,10 @@ armpmu_del(struct perf_event *event, int flags) > > armpmu_stop(event, PERF_EF_UPDATE); > hw_events->events[idx] = NULL; > - clear_bit(idx, hw_events->used_mask); > - if (armpmu->clear_event_idx) > - armpmu->clear_event_idx(hw_events, event); > - > + armpmu_clear_event_idx(armpmu, hw_events, event); > perf_event_update_userpage(event); > + /* Clear the allocated counter */ > + hwc->idx = -1; > } > > static int > -- > 2.7.4 >
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