Messages in this thread Patch in this message | | | From | Yang Jihong <> | Subject | [PATCH] perf/core: Fix account interrupt throttle | Date | Thu, 12 Jan 2023 11:38:11 +0800 |
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In literal sense of "max_samples_per_tick", if hwc->interrupts == max_samples_per_tick, it should not be throttled, therefore, the judgment condition should be changed to "hwc->interrupts > max_samples_per_tick".
In fact, this may cause the hardlockup to fail, The minimum value of max_samples_per_tick may be 1, in this case, the return value of __perf_event_account_interrupt function is 1. As a result, nmi_watchdog gets throttled, which would stop PMU (Use x86 architecture as an example, see x86_pmu_handle_irq).
Signed-off-by: Yang Jihong <yangjihong1@huawei.com> --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index d56328e5080e..ced98e028d86 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9414,7 +9414,7 @@ __perf_event_account_interrupt(struct perf_event *event, int throttle) } else { hwc->interrupts++; if (unlikely(throttle - && hwc->interrupts >= max_samples_per_tick)) { + && hwc->interrupts > max_samples_per_tick)) { __this_cpu_inc(perf_throttled_count); tick_dep_set_cpu(smp_processor_id(), TICK_DEP_BIT_PERF_EVENTS); hwc->interrupts = MAX_INTERRUPTS; -- 2.30.GIT
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