From 128f048f0f0d2a477ad2555e7acd2ad15a1b6061 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Wed, 3 Jun 2009 22:19:36 +0200 Subject: [PATCH] perf_counter: Fix throttling lock-up Throttling logic is broken and we can lock up with too small hw sampling intervals. Make the throttling code more robust: disable counters even if we already disabled them. ( Also clean up whitespace damage i noticed while reading various pieces of code related to throttling. ) Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Corey Ashford Cc: Marcelo Tosatti Cc: Arnaldo Carvalho de Melo Cc: Thomas Gleixner LKML-Reference: Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_counter.c | 2 +- kernel/perf_counter.c | 19 ++++++++++++++----- 2 files changed, 15 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 12cc05ed9f4..8f53f3a7da2 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -91,7 +91,7 @@ static u64 intel_pmu_raw_event(u64 event) #define CORE_EVNTSEL_INV_MASK 0x00800000ULL #define CORE_EVNTSEL_COUNTER_MASK 0xFF000000ULL -#define CORE_EVNTSEL_MASK \ +#define CORE_EVNTSEL_MASK \ (CORE_EVNTSEL_EVENT_MASK | \ CORE_EVNTSEL_UNIT_MASK | \ CORE_EVNTSEL_EDGE_MASK | \ diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index ab4455447f8..0bb03f15a5b 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -2822,11 +2822,20 @@ int perf_counter_overflow(struct perf_counter *counter, if (!throttle) { counter->hw.interrupts++; - } else if (counter->hw.interrupts != MAX_INTERRUPTS) { - counter->hw.interrupts++; - if (HZ*counter->hw.interrupts > (u64)sysctl_perf_counter_limit) { - counter->hw.interrupts = MAX_INTERRUPTS; - perf_log_throttle(counter, 0); + } else { + if (counter->hw.interrupts != MAX_INTERRUPTS) { + counter->hw.interrupts++; + if (HZ*counter->hw.interrupts > (u64)sysctl_perf_counter_limit) { + counter->hw.interrupts = MAX_INTERRUPTS; + perf_log_throttle(counter, 0); + ret = 1; + } + } else { + /* + * Keep re-disabling counters even though on the previous + * pass we disabled it - just in case we raced with a + * sched-in and the counter got enabled again: + */ ret = 1; } } -- 2.41.0