diff options
| author |   Cyrill Gorcunov <gorcunov@openvz.org> | 2010-06-03 01:23:04 +0400 |
|---|---|---|
| committer |   Ingo Molnar <mingo@elte.hu> | 2010-06-09 11:12:35 +0200 |
| commit | 68aa00ac0a82e9a876c799bf6be7622b8f1c8517 (patch) | |
| tree | af59ed93f50dd539389956e5fe97f3ac0cd85cbe /arch/x86/kernel/cpu/perf_event_p4.c | |
| parent | perf: Cleanup {start,commit,cancel}_txn details (diff) | |
| download | linux-dev-68aa00ac0a82e9a876c799bf6be7622b8f1c8517.tar.xz linux-dev-68aa00ac0a82e9a876c799bf6be7622b8f1c8517.zip | |
perf, x86: Make a second write to performance counter if needed
On Netburst PMU we need a second write to a performance counter
due to cpu erratum.
A simple flag test instead of alternative instructions was choosen
because wrmsrl is already a macro and if virtualization is turned
on will need an additional wrapper call which is more expencise.
nb: we should propably switch to jump-labels as only this facility
reach the mainline.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Lin Ming <ming.m.lin@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20100602212304.GC5264@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/cpu/perf_event_p4.c')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event_p4.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_p4.c b/arch/x86/kernel/cpu/perf_event_p4.c index ae85d69644d1..9286e736a70a 100644 --- a/arch/x86/kernel/cpu/perf_event_p4.c +++ b/arch/x86/kernel/cpu/perf_event_p4.c @@ -829,6 +829,15 @@ static __initconst const struct x86_pmu p4_pmu = { .max_period = (1ULL << 39) - 1, .hw_config = p4_hw_config, .schedule_events = p4_pmu_schedule_events, + /* + * This handles erratum N15 in intel doc 249199-029, + * the counter may not be updated correctly on write + * so we need a second write operation to do the trick + * (the official workaround didn't work) + * + * the former idea is taken from OProfile code + */ + .perfctr_second_write = 1, }; static __init int p4_pmu_init(void) |