linux-kernel - Re: [PATCH v1 3/5] perf tools: Check if mem

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Date:   Tue, 25 May 2021 14:14:38 +0800
From:   "Jin, Yao" <yao.jin@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v1 3/5] perf tools: Check if mem_events is supported for
 hybrid

Hi Jiri,

On 5/25/2021 1:19 AM, Jiri Olsa wrote:
> On Thu, May 20, 2021 at 03:00:38PM +0800, Jin Yao wrote:
>> Check if the mem_events ('mem-loads' and 'mem-stores') exist
>> in the sysfs path.
>>
>> For Alderlake, the hybrid cpu pmu are "cpu_core" and "cpu_atom".
>> Check the existing of following paths:
>> /sys/devices/cpu_atom/events/mem-loads
>> /sys/devices/cpu_atom/events/mem-stores
>> /sys/devices/cpu_core/events/mem-loads
>> /sys/devices/cpu_core/events/mem-stores
>>
>> If the patch exists, the mem_event is supported.
>>
>> Signed-off-by: Jin Yao <yao.jin@...ux.intel.com>
>> ---
>>   tools/perf/util/mem-events.c | 43 +++++++++++++++++++++++++++++-------
>>   1 file changed, 35 insertions(+), 8 deletions(-)
>>
>> diff --git a/tools/perf/util/mem-events.c b/tools/perf/util/mem-events.c
>> index c736eaded06c..e8f6e745eaf0 100644
>> --- a/tools/perf/util/mem-events.c
>> +++ b/tools/perf/util/mem-events.c
>> @@ -12,14 +12,16 @@
>>   #include "mem-events.h"
>>   #include "debug.h"
>>   #include "symbol.h"
>> +#include "pmu.h"
>> +#include "pmu-hybrid.h"
>>   
>>   unsigned int perf_mem_events__loads_ldlat = 30;
>>   
>>   #define E(t, n, s) { .tag = t, .name = n, .sysfs_name = s }
>>   
>>   static struct perf_mem_event perf_mem_events[PERF_MEM_EVENTS__MAX] = {
>> -	E("ldlat-loads",	"cpu/mem-loads,ldlat=%u/P",	"cpu/events/mem-loads"),
>> -	E("ldlat-stores",	"cpu/mem-stores/P",		"cpu/events/mem-stores"),
>> +	E("ldlat-loads",	"%s/mem-loads,ldlat=%u/P",	"%s/events/mem-loads"),
>> +	E("ldlat-stores",	"%s/mem-stores/P",		"%s/events/mem-stores"),
>>   	E(NULL,			NULL,				NULL),
> 
> so this was generic place, now it's x86 specific, I wonder we should
> move it under arch/x86 to avoid confusion
> 

Yes, I will move x86 specific perf_mem_events[] to arch/x86/util/mem-events.c.

>>   };
>>   #undef E
>> @@ -100,6 +102,18 @@ int perf_mem_events__parse(const char *str)
>>   	return -1;
>>   }
>>   
>> +static bool perf_mem_events__supported(const char *mnt, char *sysfs_name)
>> +{
>> +	char path[PATH_MAX];
>> +	struct stat st;
>> +
>> +	scnprintf(path, PATH_MAX, "%s/devices/%s", mnt, sysfs_name);
>> +	if (!stat(path, &st))
>> +		return true;
>> +
>> +	return false;
> 
> could be just 'return !stat(path, &st);' right?
> 

Right :)

>> +}
>> +
>>   int perf_mem_events__init(void)
>>   {
>>   	const char *mnt = sysfs__mount();
>> @@ -110,9 +124,10 @@ int perf_mem_events__init(void)
>>   		return -ENOENT;
>>   
>>   	for (j = 0; j < PERF_MEM_EVENTS__MAX; j++) {
>> -		char path[PATH_MAX];
>>   		struct perf_mem_event *e = perf_mem_events__ptr(j);
>> -		struct stat st;
>> +		struct perf_pmu *pmu;
>> +		char sysfs_name[100];
>> +		int unsupported = 0;
>>   
>>   		/*
>>   		 * If the event entry isn't valid, skip initialization
>> @@ -121,11 +136,23 @@ int perf_mem_events__init(void)
>>   		if (!e->tag)
>>   			continue;
>>   
>> -		scnprintf(path, PATH_MAX, "%s/devices/%s",
>> -			  mnt, e->sysfs_name);
>> +		if (!perf_pmu__has_hybrid()) {
>> +			scnprintf(sysfs_name, sizeof(sysfs_name),
>> +				  e->sysfs_name, "cpu");
>> +			e->supported = perf_mem_events__supported(mnt, sysfs_name);
>> +		} else {
>> +			perf_pmu__for_each_hybrid_pmu(pmu) {
>> +				scnprintf(sysfs_name, sizeof(sysfs_name),
>> +					  e->sysfs_name, pmu->name);
>> +				if (!perf_mem_events__supported(mnt, sysfs_name))
>> +					unsupported++;
>> +			}
>> +
>> +			e->supported = (unsupported == 0) ? true : false;
> 
> could you just do in the above loop:
> 			e->supported |= perf_mem_events__supported(mnt, sysfs_name);
> 

That's OK, thanks!

Thanks
Jin Yao

> jirka
> 
>> +		}
>>   
>> -		if (!stat(path, &st))
>> -			e->supported = found = true;
>> +		if (e->supported)
>> +			found = true;
>>   	}
>>   
>>   	return found ? 0 : -ENOENT;
>> -- 
>> 2.17.1
>>
>