On Sat, 2010-05-08 at 20:28 +1000, Paul Mackerras wrote:
> Here's the patch I ended up with.
Ok, I'll take this one. Thanks Paul!
One small question on the patch below:
> --------------
> Subject: perf, powerpc: Implement group scheduling transactional APIs
> From: Lin Ming <ming.m.lin@xxxxxxxxx>
>
> [paulus@xxxxxxxxx: Set cpuhw->event[i]->hw.config in
> power_pmu_commit_txn.]
>
> Signed-off-by: Lin Ming <ming.m.lin@xxxxxxxxx>
> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>
> ---
> diff --git a/arch/powerpc/kernel/perf_event.c b/arch/powerpc/kernel/perf_event.c
> index 08460a2..43b83c3 100644
> --- a/arch/powerpc/kernel/perf_event.c
> +++ b/arch/powerpc/kernel/perf_event.c
> @@ -35,6 +35,9 @@ struct cpu_hw_events {
> u64 alternatives[MAX_HWEVENTS][MAX_EVENT_ALTERNATIVES];
> unsigned long amasks[MAX_HWEVENTS][MAX_EVENT_ALTERNATIVES];
> unsigned long avalues[MAX_HWEVENTS][MAX_EVENT_ALTERNATIVES];
> +
> + unsigned int group_flag;
> + int n_txn_start;
> };
> DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);
>
> @@ -805,12 +748,22 @@ static int power_pmu_enable(struct perf_event *event)
> cpuhw->event[n0] = event;
> cpuhw->events[n0] = event->hw.config;
> cpuhw->flags[n0] = event->hw.event_base;
> +
> + /*
> + * If group events scheduling transaction was started,
> + * skip the schedulability test here, it will be peformed
> + * at commit time(->commit_txn) as a whole
> + */
> + if (cpuhw->group_flag & PERF_EVENT_TXN_STARTED)
> + goto nocheck;
> +
> if (check_excludes(cpuhw->event, cpuhw->flags, n0, 1))
> goto out;
> if (power_check_constraints(cpuhw, cpuhw->events, cpuhw->flags, n0 + 1))
> goto out;
> event->hw.config = cpuhw->events[n0];
> +
> +nocheck:
> ++cpuhw->n_events;
> ++cpuhw->n_added;
>
> @@ -896,11 +849,65 @@ static void power_pmu_unthrottle(struct perf_event *event)
> local_irq_restore(flags);
> }
>
> +/*
> + * Start group events scheduling transaction
> + * Set the flag to make pmu::enable() not perform the
> + * schedulability test, it will be performed at commit time
> + */
> +void power_pmu_start_txn(const struct pmu *pmu)
> +{
> + struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);
> +
> + cpuhw->group_flag |= PERF_EVENT_TXN_STARTED;
> + cpuhw->n_txn_start = cpuhw->n_events;
> +}
> +
> +/*
> + * Stop group events scheduling transaction
> + * Clear the flag and pmu::enable() will perform the
> + * schedulability test.
> + */
> +void power_pmu_cancel_txn(const struct pmu *pmu)
> +{
> + struct cpu_hw_events *cpuhw = &__get_cpu_var(cpu_hw_events);
> +
> + cpuhw->group_flag &= ~PERF_EVENT_TXN_STARTED;
> +}
> +
> +/*
> + * Commit group events scheduling transaction
> + * Perform the group schedulability test as a whole
> + * Return 0 if success
> + */
> +int power_pmu_commit_txn(const struct pmu *pmu)
> +{
> + struct cpu_hw_events *cpuhw;
> + long i, n;
> +
> + if (!ppmu)
> + return -EAGAIN;
> + cpuhw = &__get_cpu_var(cpu_hw_events);
> + n = cpuhw->n_events;
> + if (check_excludes(cpuhw->event, cpuhw->flags, 0, n))
> + return -EAGAIN;
> + i = power_check_constraints(cpuhw, cpuhw->events, cpuhw->flags, n);
> + if (i < 0)
> + return -EAGAIN;
> +
> + for (i = cpuhw->n_txn_start; i < n; ++i)
> + cpuhw->event[i]->hw.config = cpuhw->events[i];
> +
> + return 0;
> +}
Can't you compute n_txn_start by subtracting n_added from n_events ?
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