linux-kernel - Re: [PATCH 1/2] perf vendor events: Add stepping in CPUID string for x86

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Date:   Thu, 15 Nov 2018 10:18:27 -0500
From:   "Liang, Kan" <kan.liang@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     acme@...nel.org, mingo@...hat.com, peterz@...radead.org,
        linux-kernel@...r.kernel.org, namhyung@...nel.org,
        ak@...ux.intel.com
Subject: Re: [PATCH 1/2] perf vendor events: Add stepping in CPUID string for
 x86



On 11/15/2018 9:26 AM, Liang, Kan wrote:
> 
> 
> On 11/15/2018 8:53 AM, Jiri Olsa wrote:
>> On Wed, Nov 14, 2018 at 01:24:15PM -0800, kan.liang@...ux.intel.com 
>> wrote:
>>
>> SNIP
>>
>>> diff --git a/tools/perf/arch/x86/util/header.c 
>>> b/tools/perf/arch/x86/util/header.c
>>> index fb0d71afee8b..b428a4b00bf7 100644
>>> --- a/tools/perf/arch/x86/util/header.c
>>> +++ b/tools/perf/arch/x86/util/header.c
>>> @@ -4,6 +4,7 @@
>>>   #include <stdio.h>
>>>   #include <stdlib.h>
>>>   #include <string.h>
>>> +#include <regex.h>
>>>   #include "../../util/header.h"
>>> @@ -70,9 +71,73 @@ get_cpuid_str(struct perf_pmu *pmu __maybe_unused)
>>>   {
>>>       char *buf = malloc(128);
>>> -    if (buf && __get_cpuid(buf, 128, "%s-%u-%X$") < 0) {
>>> +    if (buf && __get_cpuid(buf, 128, "%s-%u-%X-%X$") < 0) {
>>>           free(buf);
>>>           return NULL;
>>>       }
>>>       return buf;
>>>   }
>>> +
>>> +/* Full CPUID format for x86 is vendor-family-model-stepping */
>>> +static bool is_full_cpuid(const char *cpuid)
>>> +{
>>> +    const char *tmp = cpuid;
>>> +    int count = 0;
>>> +
>>> +    while ((tmp = strchr(tmp, '-')) != NULL) {
>>> +        count++;
>>> +        tmp++;
>>> +    }
>>> +
>>> +    if (count == 3)
>>> +        return true;
>>> +
>>> +    return false;
>>> +}
>>> +
>>> +int strcmp_cpuid_str(const char *mapcpuid, const char *cpuid)
>>> +{
>>> +    regex_t re;
>>> +    regmatch_t pmatch[1];
>>> +    int match;
>>> +    bool full_mapcpuid = is_full_cpuid(mapcpuid);
>>> +    bool full_cpuid = is_full_cpuid(cpuid);
>>
>> cpuid will be always full from now right? why do we need to check it?
>>
> 
> User may set cpuid by environment string "PERF_CPUID", which may not be 
> full format.
> 
>> also please move this to arch/x86/util/pmu.c
>> so it matches the weak function object
> 
> Sure.
> 

It looks like both pmu.c and header.c have cpuid related functions.
For example,
get_cpuid_str() has weak function in pmu.c. It's declaration in 
header.h. It's x86 specific function in x86/util/header.c
get_cpuid() has weak function in header.c. It's declaration in header.h. 
It's x86 specific function in x86/util/header.c

It looks like most of the cpuid related functions are in header.c/h.
I think it may be better to move all the cpuid related functions to 
header.c/h.

If it's OK for you, I will send a clean up patch later to move the weak 
functions strcmp_cpuid_str() and get_cpuid_str() to header.c

What do you think?

Thanks,
Kan