Re: [PATCH v9 1/7] perf pmu: "Compat" supports regular expression matching identifiers

[Jing Zhang]

在 2023/9/21 上午2:36, Ian Rogers 写道:
> On Mon, Sep 18, 2023 at 4:52 AM Jing Zhang <renyu.zj@xxxxxxxxxxxxxxxxx> wrote:
>>
>> The jevent "Compat" is used for uncore PMU alias or metric definitions.
>>
>> The same PMU driver has different PMU identifiers due to different
>> hardware versions and types, but they may have some common PMU event.
>> Since a Compat value can only match one identifier, when adding the
>> same event alias to PMUs with different identifiers, each identifier
>> needs to be defined once, which is not streamlined enough.
>>
>> So let "Compat" support using regular expression to match identifiers
>> for uncore PMU alias. For example, if the "Compat" value is set to
>> "43401|43c01", it would be able to match PMU identifiers such as "43401"
>> or "43c01", which correspond to CMN600_r0p0 or CMN700_r0p0.
>>
>> Signed-off-by: Jing Zhang <renyu.zj@xxxxxxxxxxxxxxxxx>
>> ---
>>  tools/perf/util/pmu.c | 23 +++++++++++++++++++++--
>>  tools/perf/util/pmu.h |  1 +
>>  2 files changed, 22 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
>> index e215985..7e2242f 100644
>> --- a/tools/perf/util/pmu.c
>> +++ b/tools/perf/util/pmu.c
>> @@ -28,6 +28,7 @@
>>  #include "strbuf.h"
>>  #include "fncache.h"
>>  #include "util/evsel_config.h"
>> +#include <regex.h>
>>
>>  struct perf_pmu perf_pmu__fake = {
>>         .name = "fake",
>> @@ -875,6 +876,24 @@ static bool pmu_uncore_alias_match(const char *pmu_name, const char *name)
>>         return res;
>>  }
>>
>> +bool pmu_uncore_identifier_match(const char *compat, const char *id)
>> +{
>> +       regex_t re;
>> +       regmatch_t pmatch[1];
>> +       int match;
>> +
>> +       if (regcomp(&re, compat, REG_EXTENDED) != 0) {
>> +               /* Warn unable to generate match particular string. */
>> +               pr_info("Invalid regular expression %s\n", compat);
>> +               return false;
>> +       }
>> +
>> +       match = !regexec(&re, id, 1, pmatch, 0);
> 
> I wonder if we can make the regular expressions like
> "^(434|436|43c|43a)" more like "(434|436|43c|43a).*", so that we fully
> match the id string, by here doing:
> 
> if (match) {
>   /* Ensure a full match. */
>   match = pmatch[0].rm_so == 0 && pmatch[0].rm_eo == strlen(id);
> }
> 

Ok, will do.


> I think longer term we can use jevents.py to generate a pmu-events.l,
> which would have a contents something like:
> 
> (434|436|43c|43a).*  { return PMU_....;}
> 
> That should make the matching faster but may add some restrictions
> onto the regular expression.

Could you please describe the function of pmu-event.l in more detail? I may not fully understand it.

Thanks,
Jing

> 
> Thanks,
> Ian
> 
>> +       regfree(&re);
>> +
>> +       return match;
>> +}
>> +
>>  static int pmu_add_cpu_aliases_map_callback(const struct pmu_event *pe,
>>                                         const struct pmu_events_table *table __maybe_unused,
>>                                         void *vdata)
>> @@ -915,8 +934,8 @@ static int pmu_add_sys_aliases_iter_fn(const struct pmu_event *pe,
>>         if (!pe->compat || !pe->pmu)
>>                 return 0;
>>
>> -       if (!strcmp(pmu->id, pe->compat) &&
>> -           pmu_uncore_alias_match(pe->pmu, pmu->name)) {
>> +       if (pmu_uncore_alias_match(pe->pmu, pmu->name) &&
>> +                       pmu_uncore_identifier_match(pe->compat, pmu->id)) {
>>                 perf_pmu__new_alias(pmu,
>>                                 pe->name,
>>                                 pe->desc,
>> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
>> index bd5d804..fc155ce 100644
>> --- a/tools/perf/util/pmu.h
>> +++ b/tools/perf/util/pmu.h
>> @@ -240,6 +240,7 @@ void pmu_add_cpu_aliases_table(struct perf_pmu *pmu,
>>  char *perf_pmu__getcpuid(struct perf_pmu *pmu);
>>  const struct pmu_events_table *pmu_events_table__find(void);
>>  const struct pmu_metrics_table *pmu_metrics_table__find(void);
>> +bool pmu_uncore_identifier_match(const char *compat, const char *id);
>>
>>  int perf_pmu__convert_scale(const char *scale, char **end, double *sval);
>>
>> --
>> 1.8.3.1
>>