Messages in this thread | | | Subject | Re: [RESEND PATCH V2 1/4] perf/x86/intel: fix event update for auto-reload | From | "Liang, Kan" <> | Date | Wed, 10 Jan 2018 09:31:01 -0500 |
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On 1/10/2018 5:22 AM, Jiri Olsa wrote: > On Mon, Jan 08, 2018 at 07:15:13AM -0800, kan.liang@intel.com wrote: > > SNIP > >> There is nothing need to do in x86_perf_event_set_period(). Because it >> is fixed period. The period_left is already adjusted. >> >> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> >> --- >> arch/x86/events/intel/ds.c | 69 ++++++++++++++++++++++++++++++++++++++++++++-- >> 1 file changed, 67 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c >> index 3674a4b..cc1f373 100644 >> --- a/arch/x86/events/intel/ds.c >> +++ b/arch/x86/events/intel/ds.c >> @@ -1251,17 +1251,82 @@ get_next_pebs_record_by_bit(void *base, void *top, int bit) >> return NULL; >> } >> >> +/* >> + * Specific intel_pmu_save_and_restart() for auto-reload. >> + */ >> +static int intel_pmu_save_and_restart_reload(struct perf_event *event, >> + u64 reload_val, >> + int reload_times) >> +{ >> + struct hw_perf_event *hwc = &event->hw; >> + int shift = 64 - x86_pmu.cntval_bits; >> + u64 prev_raw_count, new_raw_count; >> + u64 delta; >> + >> + if ((reload_times == 0) || (reload_val == 0)) >> + return intel_pmu_save_and_restart(event); > > why is this check needed? AFAICS __intel_pmu_pebs_event is > called only if reload_times != 0 and reload_val is always > non zero for sampling >
Here is a sanity check for reload_times and reload_val. Right, usually they are non zero. I think it should not bring any issues. Right? If so, I think we may still keep it?
Thanks, Kan
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