perf_counter: Generic per counter interrupt throttle

Introduce a generic per counter interrupt throttle.

This uses the perf_counter_overflow() quick disable to throttle a specific
counter when its going too fast when a pmu->unthrottle() method is provided
which can undo the quick disable.

Power needs to implement both the quick disable and the unthrottle method.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <20090525153931.703093461@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 13 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index 8c8177f859fe..c4b543d1a86f 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -623,6 +623,18 @@ try_generic:
         return 0;
 }
 
+static void x86_pmu_unthrottle(struct perf_counter *counter)
+{
+        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
+        struct hw_perf_counter *hwc = &counter->hw;
+
+        if (WARN_ON_ONCE(hwc->idx >= X86_PMC_IDX_MAX ||
+                                cpuc->counters[hwc->idx] != counter))
+                return;
+
+        x86_pmu.enable(hwc, hwc->idx);
+}
+
 void perf_counter_print_debug(void)
 {
         u64 ctrl, status, overflow, pmc_ctrl, pmc_count, prev_left, fixed;
@@ -1038,6 +1050,7 @@ static const struct pmu pmu = {
         .enable         = x86_pmu_enable,
         .disable        = x86_pmu_disable,
         .read           = x86_pmu_read,
+        .unthrottle     = x86_pmu_unthrottle,
 };
 
 const struct pmu *hw_perf_counter_init(struct perf_counter *counter)