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Date: Tue, 3 Jul 2018 13:49:05 +0100
From: Mark Rutland <mark.rutland@....com>
To: Suzuki K Poulose <suzuki.poulose@....com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
will.deacon@....com, julien.thierry@....com, robin.murphy@....com
Subject: Re: [PATCH v4 4/7] arm_pmu: Tidy up clear_event_idx call backs
On Mon, Jul 02, 2018 at 10:59:45PM +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. To keep things tidy, mandate the implementation
> of clear_event_idx() and add it for exisiting backends.
> 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@....com>
> Cc: Will Deacon <will.deacon@....com>
> Reviewed-by: Julien Thierry <julien.thierry@....com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
> ---
> Changes since v3:
> - Add clear_event_idx call back for backends.
> ---
> arch/arm/kernel/perf_event_v6.c | 8 ++++++++
> arch/arm/kernel/perf_event_v7.c | 9 +++++++++
> arch/arm64/kernel/perf_event.c | 7 +++++++
> drivers/perf/arm_pmu.c | 7 +++----
> 4 files changed, 27 insertions(+), 4 deletions(-)
I beleive this is missing the xscale PMU code.
Otherwiwse, this looks good to me.
Thanks,
Mark.
> diff --git a/arch/arm/kernel/perf_event_v6.c b/arch/arm/kernel/perf_event_v6.c
> index 0729f98..1ae99de 100644
> --- a/arch/arm/kernel/perf_event_v6.c
> +++ b/arch/arm/kernel/perf_event_v6.c
> @@ -411,6 +411,12 @@ armv6pmu_get_event_idx(struct pmu_hw_events *cpuc,
> }
> }
>
> +static void armv6pmu_clear_event_idx(struct pmu_hw_events *cpuc,
> + struct perf_event *event)
> +{
> + clear_bit(event->hw.idx, cpuc->used_mask);
> +}
> +
> static void armv6pmu_disable_event(struct perf_event *event)
> {
> unsigned long val, mask, evt, flags;
> @@ -491,6 +497,7 @@ static void armv6pmu_init(struct arm_pmu *cpu_pmu)
> cpu_pmu->read_counter = armv6pmu_read_counter;
> cpu_pmu->write_counter = armv6pmu_write_counter;
> cpu_pmu->get_event_idx = armv6pmu_get_event_idx;
> + cpu_pmu->clear_event_idx = armv6pmu_clear_event_idx;
> cpu_pmu->start = armv6pmu_start;
> cpu_pmu->stop = armv6pmu_stop;
> cpu_pmu->map_event = armv6_map_event;
> @@ -541,6 +548,7 @@ static int armv6mpcore_pmu_init(struct arm_pmu *cpu_pmu)
> cpu_pmu->read_counter = armv6pmu_read_counter;
> cpu_pmu->write_counter = armv6pmu_write_counter;
> cpu_pmu->get_event_idx = armv6pmu_get_event_idx;
> + cpu_pmu->clear_event_idx = armv6pmu_clear_event_idx;
> cpu_pmu->start = armv6pmu_start;
> cpu_pmu->stop = armv6pmu_stop;
> cpu_pmu->map_event = armv6mpcore_map_event;
> diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c
> index fd7ce01..acb49a9 100644
> --- a/arch/arm/kernel/perf_event_v7.c
> +++ b/arch/arm/kernel/perf_event_v7.c
> @@ -1058,6 +1058,12 @@ static int armv7pmu_get_event_idx(struct pmu_hw_events *cpuc,
> return -EAGAIN;
> }
>
> +static void armv7pmu_clear_event_idx(struct pmu_hw_events *cpuc,
> + struct perf_event *event)
> +{
> + clear_bit(event->hw.idx, cpuc->used_mask);
> +}
> +
> /*
> * Add an event filter to a given event. This will only work for PMUv2 PMUs.
> */
> @@ -1167,6 +1173,7 @@ static void armv7pmu_init(struct arm_pmu *cpu_pmu)
> cpu_pmu->read_counter = armv7pmu_read_counter;
> cpu_pmu->write_counter = armv7pmu_write_counter;
> cpu_pmu->get_event_idx = armv7pmu_get_event_idx;
> + cpu_pmu->clear_event_idx = armv7pmu_clear_event_idx;
> cpu_pmu->start = armv7pmu_start;
> cpu_pmu->stop = armv7pmu_stop;
> cpu_pmu->reset = armv7pmu_reset;
> @@ -1637,6 +1644,7 @@ 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);
>
> + armv7pmu_clear_event_idx(cpuc, event);
> if (venum_event || krait_event) {
> bit = krait_event_to_bit(event, region, group);
> clear_bit(bit, cpuc->used_mask);
> @@ -1966,6 +1974,7 @@ 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);
>
> + armv7pmu_clear_event_idx(cpuc, event);
> if (venum_event || scorpion_event) {
> bit = scorpion_event_to_bit(event, region, group);
> clear_bit(bit, cpuc->used_mask);
> diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
> index 66a2ffd..ac66851 100644
> --- a/arch/arm64/kernel/perf_event.c
> +++ b/arch/arm64/kernel/perf_event.c
> @@ -778,6 +778,12 @@ static int armv8pmu_get_event_idx(struct pmu_hw_events *cpuc,
> return -EAGAIN;
> }
>
> +static void armv8pmu_clear_event_idx(struct pmu_hw_events *cpuc,
> + struct perf_event *event)
> +{
> + clear_bit(event->hw.idx, cpuc->used_mask);
> +}
> +
> /*
> * Add an event filter to a given event. This will only work for PMUv2 PMUs.
> */
> @@ -956,6 +962,7 @@ static int armv8_pmu_init(struct arm_pmu *cpu_pmu)
> cpu_pmu->read_counter = armv8pmu_read_counter,
> cpu_pmu->write_counter = armv8pmu_write_counter,
> cpu_pmu->get_event_idx = armv8pmu_get_event_idx,
> + cpu_pmu->clear_event_idx = armv8pmu_clear_event_idx,
> cpu_pmu->start = armv8pmu_start,
> cpu_pmu->stop = armv8pmu_stop,
> cpu_pmu->reset = armv8pmu_reset,
> diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
> index 8cad6b5..a288810 100644
> --- a/drivers/perf/arm_pmu.c
> +++ b/drivers/perf/arm_pmu.c
> @@ -238,11 +238,10 @@ 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(hw_events, event);
> perf_event_update_userpage(event);
> + /* Clear the allocated counter */
> + hwc->idx = -1;
> }
>
> static int
> --
> 2.7.4
>
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