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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-06-19 18:27:26 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-06-23 11:42:44 +0200 |
| commit | f29ac756a40d0f1bb07d682ea521e7b666ff06d5 (patch) | |
| tree | 6fabe2f38ae10f824e57fdd5b035ba81b75a71a8 /kernel/perf_counter.c | |
| parent | 3d906ef10a539ff336010afab8f6f9c4fe379695 (diff) | |
| download | lwn-f29ac756a40d0f1bb07d682ea521e7b666ff06d5.tar.gz lwn-f29ac756a40d0f1bb07d682ea521e7b666ff06d5.zip | |
perf_counter: Optimize perf_swcounter_event()
Similar to tracepoints, use an enable variable to reduce
overhead when unused.
Only look for a counter of a particular event type when we know
there is at least one in the system.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_counter.c')
| -rw-r--r-- | kernel/perf_counter.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 1a933a221ea4..7515c7695428 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -3317,8 +3317,8 @@ out: put_cpu_var(perf_cpu_context); } -void -perf_swcounter_event(u32 event, u64 nr, int nmi, struct pt_regs *regs, u64 addr) +void __perf_swcounter_event(u32 event, u64 nr, int nmi, + struct pt_regs *regs, u64 addr) { struct perf_sample_data data = { .regs = regs, @@ -3509,9 +3509,19 @@ static const struct pmu *tp_perf_counter_init(struct perf_counter *counter) } #endif +atomic_t perf_swcounter_enabled[PERF_COUNT_SW_MAX]; + +static void sw_perf_counter_destroy(struct perf_counter *counter) +{ + u64 event = counter->attr.config; + + atomic_dec(&perf_swcounter_enabled[event]); +} + static const struct pmu *sw_perf_counter_init(struct perf_counter *counter) { const struct pmu *pmu = NULL; + u64 event = counter->attr.config; /* * Software counters (currently) can't in general distinguish @@ -3520,7 +3530,7 @@ static const struct pmu *sw_perf_counter_init(struct perf_counter *counter) * to be kernel events, and page faults are never hypervisor * events. */ - switch (counter->attr.config) { + switch (event) { case PERF_COUNT_SW_CPU_CLOCK: pmu = &perf_ops_cpu_clock; @@ -3541,6 +3551,8 @@ static const struct pmu *sw_perf_counter_init(struct perf_counter *counter) case PERF_COUNT_SW_PAGE_FAULTS_MAJ: case PERF_COUNT_SW_CONTEXT_SWITCHES: case PERF_COUNT_SW_CPU_MIGRATIONS: + atomic_inc(&perf_swcounter_enabled[event]); + counter->destroy = sw_perf_counter_destroy; pmu = &perf_ops_generic; break; } |