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    perf: allow for PMU-specific event filtering · 66eb579e
    Mark Rutland 提交于
    In certain circumstances it may not be possible to schedule particular
    events due to constraints other than a lack of hardware counters (e.g.
    on big.LITTLE systems where CPUs support different events). The core
    perf event code does not distinguish these cases and pessimistically
    assumes that any failure to schedule an event means that it is not worth
    attempting to schedule later events, even if some hardware counters are
    still unused.
    
    When an event a pmu cannot schedule exists in a flexible group list it
    can unnecessarily prevent event groups following it in the list from
    being scheduled (until it is rotated to the end of the list). This means
    some events are scheduled for only a portion of the time they could be,
    and for short running programs no events may be scheduled if the list is
    initially sorted in an unfortunate order.
    
    This patch adds a new (optional) filter_match function pointer to struct
    pmu which a pmu driver can use to tell perf core when an event matches
    pmu-specific scheduling requirements. This plugs into the existing
    event_filter_match logic, and makes it possible to avoid the scheduling
    problem described above. When no filter is provided by the PMU, the
    existing behaviour is retained.
    
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
    Acked-by: NWill Deacon <will.deacon@arm.com>
    Acked-by: NPeter Zijlstra <peterz@infradead.org>
    Signed-off-by: NMark Rutland <mark.rutland@arm.com>
    Signed-off-by: NWill Deacon <will.deacon@arm.com>
    66eb579e
core.c 209.8 KB