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SubjectRe: [RESEND PATCH V2 1/4] perf/x86/intel: fix event update for auto-reload
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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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