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    Subject[PATCH] perf: Don't schedule tracepoints when exclude_kernel is set
    Date
    Instead of checking attr.exclude_kernel anytime a tracepoint
    event triggers, simply don't schedule the tracepoint it that
    attribute is set. This makes one test less in the tracing
    path.

    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Stephane Eranian <eranian@google.com>
    ---
    kernel/perf_event.c | 5 -----
    kernel/trace/trace_event_perf.c | 6 +++++-
    2 files changed, 5 insertions(+), 6 deletions(-)

    diff --git a/kernel/perf_event.c b/kernel/perf_event.c
    index c75925c..2f3fb90 100644
    --- a/kernel/perf_event.c
    +++ b/kernel/perf_event.c
    @@ -5491,11 +5491,6 @@ static int perf_tp_event_match(struct perf_event *event,
    {
    if (event->hw.state & PERF_HES_STOPPED)
    return 0;
    - /*
    - * All tracepoints are from kernel-space.
    - */
    - if (event->attr.exclude_kernel)
    - return 0;

    if (!perf_tp_filter_match(event, data))
    return 0;
    diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
    index 19a359d..427314b 100644
    --- a/kernel/trace/trace_event_perf.c
    +++ b/kernel/trace/trace_event_perf.c
    @@ -136,6 +136,10 @@ int perf_trace_add(struct perf_event *p_event, int flags)
    struct hlist_head __percpu *pcpu_list;
    struct hlist_head *list;

    + /* Tracepoints always trigger in the kernel */
    + if (p_event->attr.exclude_kernel)
    + return 0;
    +
    pcpu_list = tp_event->perf_events;
    if (WARN_ON_ONCE(!pcpu_list))
    return -EINVAL;
    @@ -151,7 +155,7 @@ int perf_trace_add(struct perf_event *p_event, int flags)

    void perf_trace_del(struct perf_event *p_event, int flags)
    {
    - hlist_del_rcu(&p_event->hlist_entry);
    + hlist_del_init_rcu(&p_event->hlist_entry);
    }

    void perf_trace_destroy(struct perf_event *p_event)
    --
    1.7.3.2


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