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    Subject[tip:perf/core] perf: Fix the software context switch counter
    Commit-ID:  ee6dcfa40a50fe12a3ae0fb4d2653c66c3ed6556
    Gitweb: http://git.kernel.org/tip/ee6dcfa40a50fe12a3ae0fb4d2653c66c3ed6556
    Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
    AuthorDate: Fri, 26 Nov 2010 13:49:04 +0100
    Committer: Ingo Molnar <mingo@elte.hu>
    CommitDate: Fri, 26 Nov 2010 15:00:59 +0100

    perf: Fix the software context switch counter

    Stephane noticed that because the perf_sw_event() call is inside the
    perf_event_task_sched_out() call it won't get called unless we
    have a per-task counter.

    Reported-by: Stephane Eranian <eranian@google.com>
    Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    LKML-Reference: <new-submission>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    ---
    include/linux/perf_event.h | 29 +++++++++++++++--------------
    kernel/perf_event.c | 2 --
    2 files changed, 15 insertions(+), 16 deletions(-)

    diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
    index 142e3d6..de2c417 100644
    --- a/include/linux/perf_event.h
    +++ b/include/linux/perf_event.h
    @@ -909,20 +909,6 @@ extern int perf_num_counters(void);
    extern const char *perf_pmu_name(void);
    extern void __perf_event_task_sched_in(struct task_struct *task);
    extern void __perf_event_task_sched_out(struct task_struct *task, struct task_struct *next);
    -
    -extern atomic_t perf_task_events;
    -
    -static inline void perf_event_task_sched_in(struct task_struct *task)
    -{
    - COND_STMT(&perf_task_events, __perf_event_task_sched_in(task));
    -}
    -
    -static inline
    -void perf_event_task_sched_out(struct task_struct *task, struct task_struct *next)
    -{
    - COND_STMT(&perf_task_events, __perf_event_task_sched_out(task, next));
    -}
    -
    extern int perf_event_init_task(struct task_struct *child);
    extern void perf_event_exit_task(struct task_struct *child);
    extern void perf_event_free_task(struct task_struct *task);
    @@ -1031,6 +1017,21 @@ have_event:
    __perf_sw_event(event_id, nr, nmi, regs, addr);
    }

    +extern atomic_t perf_task_events;
    +
    +static inline void perf_event_task_sched_in(struct task_struct *task)
    +{
    + COND_STMT(&perf_task_events, __perf_event_task_sched_in(task));
    +}
    +
    +static inline
    +void perf_event_task_sched_out(struct task_struct *task, struct task_struct *next)
    +{
    + perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, NULL, 0);
    +
    + COND_STMT(&perf_task_events, __perf_event_task_sched_out(task, next));
    +}
    +
    extern void perf_event_mmap(struct vm_area_struct *vma);
    extern struct perf_guest_info_callbacks *perf_guest_cbs;
    extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);
    diff --git a/kernel/perf_event.c b/kernel/perf_event.c
    index f365dd8..eac7e33 100644
    --- a/kernel/perf_event.c
    +++ b/kernel/perf_event.c
    @@ -1287,8 +1287,6 @@ void __perf_event_task_sched_out(struct task_struct *task,
    {
    int ctxn;

    - perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, NULL, 0);
    -
    for_each_task_context_nr(ctxn)
    perf_event_context_sched_out(task, ctxn, next);
    }

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