Commit 128f048f authored Jun 03, 2009 by Ingo Molnar

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 <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 233f0b95

kernel/perf_counter.c

+14 −5

Original line number	Diff line number	Diff line
		@@ -2822,13 +2822,22 @@ int perf_counter_overflow(struct perf_counter *counter,

		if (!throttle) {
		counter->hw.interrupts++;
		} else if (counter->hw.interrupts != MAX_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);
		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;
		}
		}

		/*

arch/x86/kernel/cpu/perf_counter.c

+1 −1

File changed.

Contains only whitespace changes.

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