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    Subject[RFC][PATCH 7/7] perf: Optimize sw events

    Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    ---
    include/linux/perf_event.h | 16 +++++++++-------
    kernel/perf_event.c | 4 ++--
    2 files changed, 11 insertions(+), 9 deletions(-)

    Index: linux-2.6/include/linux/perf_event.h
    ===================================================================
    --- linux-2.6.orig/include/linux/perf_event.h
    +++ linux-2.6/include/linux/perf_event.h
    @@ -1013,15 +1013,17 @@ static inline void perf_fetch_caller_reg
    static inline void
    perf_sw_event(u32 event_id, u64 nr, int nmi, struct pt_regs *regs, u64 addr)
    {
    - if (atomic_read(&perf_swevent_enabled[event_id])) {
    - struct pt_regs hot_regs;
    + struct pt_regs hot_regs;

    - if (!regs) {
    - perf_fetch_caller_regs(&hot_regs);
    - regs = &hot_regs;
    - }
    - __perf_sw_event(event_id, nr, nmi, regs, addr);
    + JUMP_LABEL(&perf_swevent_enabled[event_id], have_event);
    + return;
    +
    +have_event:
    + if (!regs) {
    + perf_fetch_caller_regs(&hot_regs);
    + regs = &hot_regs;
    }
    + __perf_sw_event(event_id, nr, nmi, regs, addr);
    }

    extern void perf_event_mmap(struct vm_area_struct *vma);
    Index: linux-2.6/kernel/perf_event.c
    ===================================================================
    --- linux-2.6.orig/kernel/perf_event.c
    +++ linux-2.6/kernel/perf_event.c
    @@ -4603,7 +4603,7 @@ static void sw_perf_event_destroy(struct

    WARN_ON(event->parent);

    - atomic_dec(&perf_swevent_enabled[event_id]);
    + jump_label_dec(&perf_swevent_enabled[event_id]);
    swevent_hlist_put(event);
    }

    @@ -4633,7 +4633,7 @@ static int perf_swevent_init(struct perf
    if (err)
    return err;

    - atomic_inc(&perf_swevent_enabled[event_id]);
    + jump_label_inc(&perf_swevent_enabled[event_id]);
    event->destroy = sw_perf_event_destroy;
    }




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