Messages in this thread Patch in this message | | | Date | Thu, 13 Feb 2020 23:51:31 -0800 | Subject | [PATCH v6 4/6] perf: Add per perf_cpu_context min_heap storage | From | Ian Rogers <> |
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The storage required for visit_groups_merge's min heap needs to vary in order to support more iterators, such as when multiple nested cgroups' events are being visited. This change allows for 2 iterators and doesn't support growth. Based-on-work-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ian Rogers <irogers@google.com> --- include/linux/perf_event.h | 7 +++++ kernel/events/core.c | 53 ++++++++++++++++++++++++++------------ 2 files changed, 44 insertions(+), 16 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 68e21e828893..5060e31b32cc 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -862,6 +862,13 @@ struct perf_cpu_context { int sched_cb_usage; int online; + /* + * Per-CPU storage for iterators used in visit_groups_merge. The default + * storage is of size 2 to hold the CPU and any CPU event iterators. + */ + int itr_storage_cap; + struct perf_event **itr_storage; + struct perf_event *itr_default[2]; }; struct perf_output_handle { diff --git a/kernel/events/core.c b/kernel/events/core.c index 832e2a56a663..18e4bb871d85 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3419,36 +3419,48 @@ static void __heap_add(struct min_heap *heap, struct perf_event *event) } } -static noinline int visit_groups_merge(struct perf_event_groups *groups, - int cpu, +static noinline int visit_groups_merge(struct perf_cpu_context *cpuctx, + struct perf_event_groups *groups, int cpu, int (*func)(struct perf_event *, void *), void *data) { /* Space for per CPU and/or any CPU event iterators. */ struct perf_event *itrs[2]; - struct min_heap event_heap = { - .data = itrs, - .size = 0, - .cap = ARRAY_SIZE(itrs), - }; + struct min_heap event_heap; + struct perf_event **evt; struct perf_event *next; int ret; - __heap_add(&event_heap, perf_event_groups_first(groups, -1)); + if (cpuctx) { + event_heap = (struct min_heap){ + .data = cpuctx->itr_storage, + .size = 0, + .cap = cpuctx->itr_storage_cap, + }; + } else { + event_heap = (struct min_heap){ + .data = itrs, + .size = 0, + .cap = ARRAY_SIZE(itrs), + }; + /* Events not within a CPU context may be on any CPU. */ + __heap_add(&event_heap, perf_event_groups_first(groups, -1)); + } + evt = event_heap.data; + __heap_add(&event_heap, perf_event_groups_first(groups, cpu)); min_heapify_all(&event_heap, &perf_min_heap); while (event_heap.size) { - ret = func(itrs[0], data); + ret = func(*evt, data); if (ret) return ret; - next = perf_event_groups_next(itrs[0]); - if (next) { - min_heap_pop_push(&event_heap, &next, - &perf_min_heap); - } else + next = perf_event_groups_next(*evt); + if (next) + min_heap_pop_push(&event_heap, &next, &perf_min_heap); + else min_heap_pop(&event_heap, &perf_min_heap); } @@ -3519,7 +3531,10 @@ ctx_pinned_sched_in(struct perf_event_context *ctx, .can_add_hw = 1, }; - visit_groups_merge(&ctx->pinned_groups, + if (ctx != &cpuctx->ctx) + cpuctx = NULL; + + visit_groups_merge(cpuctx, &ctx->pinned_groups, smp_processor_id(), pinned_sched_in, &sid); } @@ -3534,7 +3549,10 @@ ctx_flexible_sched_in(struct perf_event_context *ctx, .can_add_hw = 1, }; - visit_groups_merge(&ctx->flexible_groups, + if (ctx != &cpuctx->ctx) + cpuctx = NULL; + + visit_groups_merge(cpuctx, &ctx->flexible_groups, smp_processor_id(), flexible_sched_in, &sid); } @@ -10395,6 +10413,9 @@ int perf_pmu_register(struct pmu *pmu, const char *name, int type) cpuctx->online = cpumask_test_cpu(cpu, perf_online_mask); __perf_mux_hrtimer_init(cpuctx, cpu); + + cpuctx->itr_storage_cap = ARRAY_SIZE(cpuctx->itr_default); + cpuctx->itr_storage = cpuctx->itr_default; } got_cpu_context: -- 2.25.0.265.gbab2e86ba0-goog
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