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SubjectRe: [PATCH V4 02/16] perf, core: introduce pmu context switch callback
On Mon, Jun 30, 2014 at 04:50:39PM +0800, Yan, Zheng wrote:
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index 707617a..71fb77a 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -262,6 +262,12 @@ struct pmu {
> * flush branch stack on context-switches (needed in cpu-wide mode)
> */
> void (*flush_branch_stack) (void);
> +
> + /*
> + * PMU callback for context-switches. optional
> + */
> + void (*sched_task) (struct perf_event_context *ctx,
> + bool sched_in);
> };

Here you make it a general facility..

> +/*
> + * This function provides the context switch callback to the lower code
> + * layer. It is invoked ONLY when the context switch callback is enabled.
> + */
> +static void perf_pmu_sched_task(struct task_struct *prev,
> + struct task_struct *next,
> + bool sched_in)
> +{
> + struct perf_cpu_context *cpuctx;
> + struct pmu *pmu;
> + unsigned long flags;
> +
> + if (prev == next)
> + return;
> +
> + local_irq_save(flags);
> +
> + rcu_read_lock();
> +
> + list_for_each_entry_rcu(pmu, &pmus, entry) {
> + if (pmu->sched_task) {
> + cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
> +
> + perf_ctx_lock(cpuctx, cpuctx->task_ctx);
> +
> + perf_pmu_disable(pmu);
> +
> + pmu->sched_task(cpuctx->task_ctx, sched_in);
> +
> + perf_pmu_enable(pmu);
> +
> + perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
> + /* only CPU PMU has context switch callback */
> + break;

And here you break it..

> + }
> + }
> +
> + rcu_read_unlock();
> +
> + local_irq_restore(flags);
> +}
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