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perf/core: Optimize perf_init_event()
Andi reported that he was hitting the linear search in perf_init_event() a lot. Make more agressive use of the IDR lookup to avoid hitting the linear search. With exception of PERF_TYPE_SOFTWARE (which relies on a hideous hack), we can put everything in the IDR. On top of that, we can alias TYPE_HARDWARE and TYPE_HW_CACHE to TYPE_RAW on the lookup side. This greatly reduces the chances of hitting the linear search. Reported-by: Andi Kleen <andi@firstfloor.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Kan <kan.liang@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Ingo Molnar <mingo@kernel.org>
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parent
db0503e4f6
commit
66d258c5b0
@ -10080,7 +10080,7 @@ static struct lock_class_key cpuctx_lock;
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int perf_pmu_register(struct pmu *pmu, const char *name, int type)
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{
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int cpu, ret;
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int cpu, ret, max = PERF_TYPE_MAX;
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mutex_lock(&pmus_lock);
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ret = -ENOMEM;
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@ -10093,12 +10093,17 @@ int perf_pmu_register(struct pmu *pmu, const char *name, int type)
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goto skip_type;
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pmu->name = name;
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if (type < 0) {
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type = idr_alloc(&pmu_idr, pmu, PERF_TYPE_MAX, 0, GFP_KERNEL);
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if (type < 0) {
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ret = type;
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if (type != PERF_TYPE_SOFTWARE) {
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if (type >= 0)
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max = type;
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ret = idr_alloc(&pmu_idr, pmu, max, 0, GFP_KERNEL);
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if (ret < 0)
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goto free_pdc;
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}
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WARN_ON(type >= 0 && ret != type);
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type = ret;
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}
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pmu->type = type;
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@ -10188,7 +10193,7 @@ free_dev:
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put_device(pmu->dev);
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free_idr:
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if (pmu->type >= PERF_TYPE_MAX)
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if (pmu->type != PERF_TYPE_SOFTWARE)
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idr_remove(&pmu_idr, pmu->type);
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free_pdc:
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@ -10210,7 +10215,7 @@ void perf_pmu_unregister(struct pmu *pmu)
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synchronize_rcu();
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free_percpu(pmu->pmu_disable_count);
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if (pmu->type >= PERF_TYPE_MAX)
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if (pmu->type != PERF_TYPE_SOFTWARE)
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idr_remove(&pmu_idr, pmu->type);
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if (pmu_bus_running) {
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if (pmu->nr_addr_filters)
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@ -10280,9 +10285,8 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event)
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static struct pmu *perf_init_event(struct perf_event *event)
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{
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int idx, type, ret;
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struct pmu *pmu;
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int idx;
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int ret;
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idx = srcu_read_lock(&pmus_srcu);
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@ -10295,12 +10299,27 @@ static struct pmu *perf_init_event(struct perf_event *event)
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}
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rcu_read_lock();
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pmu = idr_find(&pmu_idr, event->attr.type);
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/*
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* PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE
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* are often aliases for PERF_TYPE_RAW.
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*/
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type = event->attr.type;
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if (type == PERF_TYPE_HARDWARE || type == PERF_TYPE_HW_CACHE)
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type = PERF_TYPE_RAW;
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again:
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pmu = idr_find(&pmu_idr, type);
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rcu_read_unlock();
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if (pmu) {
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ret = perf_try_init_event(pmu, event);
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if (ret == -ENOENT && event->attr.type != type) {
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type = event->attr.type;
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goto again;
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}
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if (ret)
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pmu = ERR_PTR(ret);
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goto unlock;
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}
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