Re: [PATCH] perf mem: enable simultaneous sampling of loads/stores

[Stephane Eranian]

On Tue, Dec 16, 2014 at 3:44 PM, Arnaldo Carvalho de Melo
<acme@xxxxxxxxxx> wrote:
>
> Em Tue, Dec 16, 2014 at 05:53:58PM +0100, Stephane Eranian escreveu:
> >
> > This patch modifies perf mem to default to sampling loads
> > and stores simultaneously. It could only do one or the other
> > before yet there was not hardware restriction preventing
> > simultaneous collection. With this patch, one run is sufficient
> > to collect both.
> >
> > By default load/stores are sampled now:
> > $ perf mem rec
> > $ perf mem rep
> >
> > It is still possible to sample only loads or stores by using the
> > -t option:
> >  $ perf mem -t load rec
> >  $ perf mem -t load rep
> > Or
> >  $ perf mem -t store rec
> >  $ perf mem -t store rep
> >
> > The perf report TUI will show one event at a time. The store
> > output will contain a Weight column which will be empty.
>
> Can you please update the man page and resubmit?
>
Ok, will do that.

>
> Are those unchecked strdups really needed?
>
Well, it all boils down to how cmd_xx() declares argv:
    - const char **argv
    - char *argv

If the latter, then cannot simply do rec[i++] = "report"
otherwise we may crash it the ever decides to modify that string.

Given that cmd_record() and cmd_report() use const char *argv, then
I can use literals. Right?

>
> - Arnaldo
>
> > Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
> > ---
> >  tools/perf/builtin-mem.c | 107 ++++++++++++++++++++++++++++++++++++++++-------
> >  1 file changed, 92 insertions(+), 15 deletions(-)
> >
> > diff --git a/tools/perf/builtin-mem.c b/tools/perf/builtin-mem.c
> > index 24db6ff..52dbaae 100644
> > --- a/tools/perf/builtin-mem.c
> > +++ b/tools/perf/builtin-mem.c
> > @@ -7,10 +7,13 @@
> >  #include "util/session.h"
> >  #include "util/data.h"
> >
> > -#define MEM_OPERATION_LOAD   "load"
> > -#define MEM_OPERATION_STORE  "store"
> > +#define MEM_OPERATION_LOAD   0x1
> > +#define MEM_OPERATION_STORE  0x2
> >
> > -static const char    *mem_operation          = MEM_OPERATION_LOAD;
> > +/*
> > + * default to both load an store sampling
> > + */
> > +static int mem_operation = MEM_OPERATION_LOAD | MEM_OPERATION_STORE;
> >
> >  struct perf_mem {
> >       struct perf_tool        tool;
> > @@ -25,26 +28,30 @@ static int __cmd_record(int argc, const char **argv)
> >  {
> >       int rec_argc, i = 0, j;
> >       const char **rec_argv;
> > -     char event[64];
> >       int ret;
> >
> > -     rec_argc = argc + 4;
> > +     rec_argc = argc + 7; /* max number of arguments */
> >       rec_argv = calloc(rec_argc + 1, sizeof(char *));
> >       if (!rec_argv)
> >               return -1;
> >
> >       rec_argv[i++] = strdup("record");
> > -     if (!strcmp(mem_operation, MEM_OPERATION_LOAD))
> > +
> > +     if (mem_operation & MEM_OPERATION_LOAD)
> >               rec_argv[i++] = strdup("-W");
> > +
> >       rec_argv[i++] = strdup("-d");
> > -     rec_argv[i++] = strdup("-e");
> >
> > -     if (strcmp(mem_operation, MEM_OPERATION_LOAD))
> > -             sprintf(event, "cpu/mem-stores/pp");
> > -     else
> > -             sprintf(event, "cpu/mem-loads/pp");
> > +     if (mem_operation & MEM_OPERATION_LOAD) {
> > +             rec_argv[i++] = strdup("-e");
> > +             rec_argv[i++] = strdup("cpu/mem-loads/pp");
> > +     }
> > +
> > +     if (mem_operation & MEM_OPERATION_STORE) {
> > +             rec_argv[i++] = strdup("-e");
> > +             rec_argv[i++] = strdup("cpu/mem-stores/pp");
> > +     }
> >
> > -     rec_argv[i++] = strdup(event);
> >       for (j = 1; j < argc; j++, i++)
> >               rec_argv[i] = argv[j];
> >
> > @@ -170,7 +177,7 @@ static int report_events(int argc, const char **argv, struct perf_mem *mem)
> >        * there is no weight (cost) associated with stores, so don't print
> >        * the column
> >        */
> > -     if (strcmp(mem_operation, MEM_OPERATION_LOAD))
> > +     if (!(mem_operation & MEM_OPERATION_LOAD))
> >               rep_argv[i++] = strdup("--sort=mem,sym,dso,symbol_daddr,"
> >                                      "dso_daddr,tlb,locked");
> >
> > @@ -182,6 +189,75 @@ static int report_events(int argc, const char **argv, struct perf_mem *mem)
> >       return ret;
> >  }
> >
> > +struct mem_mode {
> > +     const char *name;
> > +     int mode;
> > +};
> > +
> > +#define MEM_OPT(n, m) \
> > +     { .name = n, .mode = (m) }
> > +
> > +#define MEM_END { .name = NULL }
> > +
> > +static const struct mem_mode mem_modes[]={
> > +     MEM_OPT("load", MEM_OPERATION_LOAD),
> > +     MEM_OPT("store", MEM_OPERATION_STORE),
> > +     MEM_END
> > +};
> > +
> > +static int
> > +parse_mem_ops(const struct option *opt, const char *str, int unset)
> > +{
> > +     int *mode = (int *)opt->value;
> > +     const struct mem_mode *m;
> > +     char *s, *os = NULL, *p;
> > +     int ret = -1;
> > +
> > +     if (unset)
> > +             return 0;
> > +
> > +     /* str may be NULL in case no arg is passed to -t */
> > +     if (str) {
> > +             /* because str is read-only */
> > +             s = os = strdup(str);
> > +             if (!s)
> > +                     return -1;
> > +
> > +             /* reset mode */
> > +             *mode = 0;
> > +
> > +             for (;;) {
> > +                     p = strchr(s, ',');
> > +                     if (p)
> > +                             *p = '\0';
> > +
> > +                     for (m = mem_modes; m->name; m++) {
> > +                             if (!strcasecmp(s, m->name))
> > +                                     break;
> > +                     }
> > +                     if (!m->name) {
> > +                             fprintf(stderr, "unknown sampling op %s,"
> > +                                         " check man page\n", s);
> > +                             goto error;
> > +                     }
> > +
> > +                     *mode |= m->mode;
> > +
> > +                     if (!p)
> > +                             break;
> > +
> > +                     s = p + 1;
> > +             }
> > +     }
> > +     ret = 0;
> > +
> > +     if (*mode == 0)
> > +             *mode = MEM_OPERATION_LOAD;
> > +error:
> > +     free(os);
> > +     return ret;
> > +}
> > +
> >  int cmd_mem(int argc, const char **argv, const char *prefix __maybe_unused)
> >  {
> >       struct stat st;
> > @@ -199,8 +275,9 @@ int cmd_mem(int argc, const char **argv, const char *prefix __maybe_unused)
> >               .input_name              = "perf.data",
> >       };
> >       const struct option mem_options[] = {
> > -     OPT_STRING('t', "type", &mem_operation,
> > -                "type", "memory operations(load/store)"),
> > +     OPT_CALLBACK('t', "type", &mem_operation,
> > +                "type", "memory operations(load,store) Default load,store",
> > +                 parse_mem_ops),
> >       OPT_BOOLEAN('D', "dump-raw-samples", &mem.dump_raw,
> >                   "dump raw samples in ASCII"),
> >       OPT_BOOLEAN('U', "hide-unresolved", &mem.hide_unresolved,
> > --
> > 1.9.1
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