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SubjectRe: [PATCH v2 2/5] perf pmu: Support more complex PMU event aliasing
On Mon, Jun 17, 2019 at 10:06:08AM +0100, John Garry wrote:
> On 16/06/2019 10:58, Jiri Olsa wrote:
> > On Fri, Jun 14, 2019 at 10:08:00PM +0800, John Garry wrote:
> > > The jevent "Unit" field is used for uncore PMU alias definition.
> > >
> > > The form uncore_pmu_example_X is supported, where "X" is a wildcard,
> > > to support multiple instances of the same PMU in a system.
> > >
> > > Unfortunately this format not suitable for all uncore PMUs; take the Hisi
> > > DDRC uncore PMU for example, where the name is in the form
> > > hisi_scclX_ddrcY.
> > >
> > > For the current jevent parsing, we would be required to hardcode an uncore
> > > alias translation for each possible value of X. This is not scalable.
> > >
> > > Instead, add support for "Unit" field in the form "hisi_sccl,ddrc", where
> > > we can match by hisi_scclX and ddrcY. Tokens in Unit field are
> > > delimited by ','.
> > >
> > > Signed-off-by: John Garry <john.garry@huawei.com>
> > > ---
> > > tools/perf/util/pmu.c | 39 ++++++++++++++++++++++++++++++++++-----
> > > 1 file changed, 34 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> > > index 7e7299fee550..bc71c60589b5 100644
> > > --- a/tools/perf/util/pmu.c
> > > +++ b/tools/perf/util/pmu.c
> > > @@ -700,6 +700,39 @@ struct pmu_events_map *perf_pmu__find_map(struct perf_pmu *pmu)
> > > return map;
> > > }
> > >
> > > +static bool pmu_uncore_alias_match(const char *pmu_name, const char *name)
> > > +{
> > > + char *tmp, *tok, *str;
> > > + bool res;
> > > +
> > > + str = strdup(pmu_name);
> > > + if (!str)
> > > + return false;
> > > +
> > > + /*
> > > + * uncore alias may be from different PMU with common
> > > + * prefix or matching tokens.
> > > + */
> > > + tok = strtok_r(str, ",", &tmp);
> > > + if (strncmp(pmu_name, tok, strlen(tok))) {
> >
>
> Hi Jirka,

heya,
sry for late reply

>
> > if tok is NULL in here we crash
> >
>
> As I see, tok could not be NULL. If str contains no delimiters, then we just
> return same as str in tok.
>
> Can you see tok being NULL?

well, if there's no ',' in the str it returns NULL, right?
and IIUC this function is still called for standard uncore
pmu names

>
> > > + res = false;
> > > + goto out;
> > > + }
> > > +
> > > + for (; tok; name += strlen(tok), tok = strtok_r(NULL, ",", &tmp)) {
> >
> > why is name shifted in here?
>
> I want to ensure that we match the tokens in order and also guard against
> possible repeated token matches in 'name'.

i might not understand this correctly.. so

str is the alias name that can contain ',' now, like:
hisi_sccl,ddrc

and name is still pmu with no ',' ... please make this or
proper version that in some comment

thanks,
jirka

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