linux-kernel - Re: [PATCH v5 1/2] perf pmus: Sort pmus by name then suffix

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Date:   Fri, 25 Aug 2023 13:49:56 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Ravi Bangoria <ravi.bangoria@....com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        John Garry <john.g.garry@...cle.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/2] perf pmus: Sort pmus by name then suffix

Em Fri, Aug 25, 2023 at 08:56:44AM -0700, Ian Rogers escreveu:
> On Fri, Aug 25, 2023 at 7:51 AM Arnaldo Carvalho de Melo
> <acme@...nel.org> wrote:
> >
> > Em Fri, Aug 25, 2023 at 11:48:08AM -0300, Arnaldo Carvalho de Melo escreveu:
> > > Em Fri, Aug 25, 2023 at 06:52:36AM -0700, Ian Rogers escreveu:
> > > > Sort PMUs by name. If two PMUs have the same name but differ by
> > > > suffix, sort the suffixes numerically. For example, "breakpoint" comes
> > > > before "cpu", "uncore_imc_free_running_0" comes before
> > > > "uncore_imc_free_running_1". Suffixes need to be treated specially as
> > > > otherwise they will be ordered like 0, 1, 10, 11, .., 2, 20, 21, ..,
> > > > etc. Only PMUs starting 'uncore_' are considered to have a potential
> > > > suffix.
> > > >
> > > > Sorting of PMUs is done so that later patches can skip duplicate
> > > > uncore PMUs that differ only by there suffix.
> > > >
> > > > Signed-off-by: Ian Rogers <irogers@...gle.com>
> > > > ---
> > > >  tools/perf/util/pmus.c | 48 ++++++++++++++++++++++++++++++++++++++++++
> > > >  1 file changed, 48 insertions(+)
> > > >
> > > > diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c
> > > > index 4dd5912617ff..b1f6a64693fe 100644
> > > > --- a/tools/perf/util/pmus.c
> > > > +++ b/tools/perf/util/pmus.c
> > > > @@ -1,8 +1,10 @@
> > > >  // SPDX-License-Identifier: GPL-2.0
> > > >  #include <linux/list.h>
> > > > +#include <linux/list_sort.h>
> > > >  #include <linux/zalloc.h>
> > > >  #include <subcmd/pager.h>
> > > >  #include <sys/types.h>
> > > > +#include <ctype.h>
> > > >  #include <dirent.h>
> > > >  #include <pthread.h>
> > > >  #include <string.h>
> > > > @@ -33,6 +35,31 @@ static LIST_HEAD(other_pmus);
> > > >  static bool read_sysfs_core_pmus;
> > > >  static bool read_sysfs_all_pmus;
> > > >
> > > > +static int pmu_name_len_no_suffix(const char *str, unsigned long *num)
> > > > +{
> > > > +   int orig_len, len;
> > > > +
> > > > +   orig_len = len = strlen(str);
> > > > +
> > > > +   /* Non-uncore PMUs have their full length, for example, i915. */
> > > > +   if (strncmp(str, "uncore_", 7))
> > > > +           return len;
> > >
> > > I applied the patch, but we have strstarts() for this case, to avoid
> > > having to count the size of the prefix in tools/include/linux/string.h,
> > > that we copied from the kernel sources:
> > >
> > > /**
> > >  * strstarts - does @str start with @prefix?
> > >  * @str: string to examine
> > >  * @prefix: prefix to look for.
> > >  */
> > > static inline bool strstarts(const char *str, const char *prefix)
> > > {
> > >         return strncmp(str, prefix, strlen(prefix)) == 0;
> > > }
> > >
> > > I'll change it, ok?
> 
> Makes sense to me. We also do this same strncmp here:
> https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/util/parse-events.y?h=perf-tools-next#n315

I did it in this case, to keep 'git blame' info in place, will look for
the other cases and do it.

This is something that should be automated somehow, maybe here is a good
opportunity for checkpatch to do something useful :-)

- Arnaldo

> So perhaps do a follow up patch cleaning up all instances of the not
> use of strstarts.
> 
> Thanks,
> Ian
> 
> > This:
> >
> > diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c
> > index b1f6a64693fe0d49..bbf84ccc3aba7d5c 100644
> > --- a/tools/perf/util/pmus.c
> > +++ b/tools/perf/util/pmus.c
> > @@ -1,6 +1,7 @@
> >  // SPDX-License-Identifier: GPL-2.0
> >  #include <linux/list.h>
> >  #include <linux/list_sort.h>
> > +#include <linux/string.h>
> >  #include <linux/zalloc.h>
> >  #include <subcmd/pager.h>
> >  #include <sys/types.h>
> > @@ -42,7 +43,7 @@ static int pmu_name_len_no_suffix(const char *str, unsigned long *num)
> >         orig_len = len = strlen(str);
> >
> >         /* Non-uncore PMUs have their full length, for example, i915. */
> > -       if (strncmp(str, "uncore_", 7))
> > +       if (!strstarts(str, "uncore_"))
> >                 return len;
> >
> >         /*

-- 

- Arnaldo