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| author | Ingo Molnar <mingo@elte.hu> | 2009-05-17 10:04:45 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-05-17 12:27:37 +0200 |
| commit | d2517a49d55536b38c7a87e5289550cfedaa4dcc (patch) | |
| tree | ee36f662094f0f09575cd2fbc4e6a67a716081d0 /arch | |
| parent | 0203026b58b4299ba7281c0b4b417207c1f05d0e (diff) | |
| download | blackbird-op-linux-d2517a49d55536b38c7a87e5289550cfedaa4dcc.tar.gz blackbird-op-linux-d2517a49d55536b38c7a87e5289550cfedaa4dcc.zip | |
perf_counter, x86: fix zero irq_period counters
The quirk to irq_period unearthed an unrobustness we had in the
hw_counter initialization sequence: we left irq_period at 0, which
was then quirked up to 2 ... which then generated a _lot_ of
interrupts during 'perf stat' runs, slowed them down and skewed
the counter results in general.
Initialize irq_period to the maximum instead.
[ Impact: fix perf stat results ]
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_counter.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 886dcf334bc3..5bfd30ab3920 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -286,6 +286,9 @@ static int __hw_perf_counter_init(struct perf_counter *counter) hwc->nmi = 1; } + if (!hwc->irq_period) + hwc->irq_period = x86_pmu.max_period; + atomic64_set(&hwc->period_left, min(x86_pmu.max_period, hwc->irq_period)); |
