linux-kernel - Re: [PATCH 2/4] perf: Add filter_match() as a parameter for pinned/flexible_sched

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Date:   Mon, 29 Apr 2019 11:31:26 -0400
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Mark Rutland <mark.rutland@....com>
Cc:     peterz@...radead.org, tglx@...utronix.de, mingo@...hat.com,
        linux-kernel@...r.kernel.org, eranian@...gle.com, tj@...nel.org,
        ak@...ux.intel.com
Subject: Re: [PATCH 2/4] perf: Add filter_match() as a parameter for
 pinned/flexible_sched_in()



On 4/29/2019 11:12 AM, Mark Rutland wrote:
> On Mon, Apr 29, 2019 at 07:44:03AM -0700, kan.liang@...ux.intel.com wrote:
>> From: Kan Liang <kan.liang@...ux.intel.com>
>>
>> A fast path will be introduced in the following patches to speed up the
>> cgroup events sched in, which only needs a simpler filter_match().
>>
>> Add filter_match() as a parameter for pinned/flexible_sched_in().
>>
>> No functional change.
> 
> I suspect that the cost you're trying to avoid is pmu_filter_match()
> iterating over the entire group, which arm systems rely upon for correct
> behaviour on big.LITTLE systems.
> 
> Is that the case?

No. In X86, we don't use pmu_filter_match(). The fast path still keeps 
this filter.
perf_cgroup_match() is the one I want to avoid.

Thanks,
Kan

> 
> Thanks,
> Mark.
> 
>>
>> Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
>> ---
>>   kernel/events/core.c | 15 +++++++++------
>>   1 file changed, 9 insertions(+), 6 deletions(-)
>>
>> diff --git a/kernel/events/core.c b/kernel/events/core.c
>> index 388dd42..782fd86 100644
>> --- a/kernel/events/core.c
>> +++ b/kernel/events/core.c
>> @@ -3251,7 +3251,8 @@ static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
>>   }
>>   
>>   static int visit_groups_merge(struct perf_event_groups *groups, int cpu,
>> -			      int (*func)(struct perf_event *, void *), void *data)
>> +			      int (*func)(struct perf_event *, void *, int (*)(struct perf_event *)),
>> +			      void *data)
>>   {
>>   	struct perf_event **evt, *evt1, *evt2;
>>   	int ret;
>> @@ -3271,7 +3272,7 @@ static int visit_groups_merge(struct perf_event_groups *groups, int cpu,
>>   			evt = &evt2;
>>   		}
>>   
>> -		ret = func(*evt, data);
>> +		ret = func(*evt, data, event_filter_match);
>>   		if (ret)
>>   			return ret;
>>   
>> @@ -3287,7 +3288,8 @@ struct sched_in_data {
>>   	int can_add_hw;
>>   };
>>   
>> -static int pinned_sched_in(struct perf_event *event, void *data)
>> +static int pinned_sched_in(struct perf_event *event, void *data,
>> +			   int (*filter_match)(struct perf_event *))
>>   {
>>   	struct sched_in_data *sid = data;
>>   
>> @@ -3300,7 +3302,7 @@ static int pinned_sched_in(struct perf_event *event, void *data)
>>   		return 0;
>>   #endif
>>   
>> -	if (!event_filter_match(event))
>> +	if (!filter_match(event))
>>   		return 0;
>>   
>>   	if (group_can_go_on(event, sid->cpuctx, sid->can_add_hw)) {
>> @@ -3318,7 +3320,8 @@ static int pinned_sched_in(struct perf_event *event, void *data)
>>   	return 0;
>>   }
>>   
>> -static int flexible_sched_in(struct perf_event *event, void *data)
>> +static int flexible_sched_in(struct perf_event *event, void *data,
>> +			     int (*filter_match)(struct perf_event *))
>>   {
>>   	struct sched_in_data *sid = data;
>>   
>> @@ -3331,7 +3334,7 @@ static int flexible_sched_in(struct perf_event *event, void *data)
>>   		return 0;
>>   #endif
>>   
>> -	if (!event_filter_match(event))
>> +	if (!filter_match(event))
>>   		return 0;
>>   
>>   	if (group_can_go_on(event, sid->cpuctx, sid->can_add_hw)) {
>> -- 
>> 2.7.4
>>