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    Subject[PATCH 4/4] perf: Better order flexible and pinned scheduling
    Date
    When a task gets scheduled in. We don't touch the cpu bound events
    so the priority order becomes:

    cpu pinned, cpu flexible, task pinned, task flexible.

    So schedule out cpu flexibles when a new task context gets in
    and correctly order the groups to schedule in:

    task pinned, cpu flexible, task flexible.

    Cpu pinned groups don't need to be touched at this time.

    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
    ---
    kernel/perf_event.c | 34 +++++++++++++++++++++++++++-------
    1 files changed, 27 insertions(+), 7 deletions(-)

    diff --git a/kernel/perf_event.c b/kernel/perf_event.c
    index a90ae69..edc46b9 100644
    --- a/kernel/perf_event.c
    +++ b/kernel/perf_event.c
    @@ -1362,6 +1362,14 @@ ctx_sched_in(struct perf_event_context *ctx,
    raw_spin_unlock(&ctx->lock);
    }

    +static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
    + enum event_type_t event_type)
    +{
    + struct perf_event_context *ctx = &cpuctx->ctx;
    +
    + ctx_sched_in(ctx, cpuctx, event_type);
    +}
    +
    static void task_ctx_sched_in(struct task_struct *task,
    enum event_type_t event_type)
    {
    @@ -1388,15 +1396,27 @@ static void task_ctx_sched_in(struct task_struct *task,
    */
    void perf_event_task_sched_in(struct task_struct *task)
    {
    - task_ctx_sched_in(task, EVENT_ALL);
    -}
    + struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context);
    + struct perf_event_context *ctx = task->perf_event_ctxp;

    -static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
    - enum event_type_t event_type)
    -{
    - struct perf_event_context *ctx = &cpuctx->ctx;
    + if (likely(!ctx))
    + return;

    - ctx_sched_in(ctx, cpuctx, event_type);
    + if (cpuctx->task_ctx == ctx)
    + return;
    +
    + /*
    + * We want to keep the following priority order:
    + * cpu pinned (that don't need to move), task pinned,
    + * cpu flexible, task flexible.
    + */
    + cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
    +
    + ctx_sched_in(ctx, cpuctx, EVENT_PINNED);
    + cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
    + ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE);
    +
    + cpuctx->task_ctx = ctx;
    }

    #define MAX_INTERRUPTS (~0ULL)
    --
    1.6.2.3


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