Re: [PATCH perf/core 03/10] perf-probe: Make --list shows only available cached events

Masami Hiramatsu
2016-07-14T06:14:25Z

On Wed, 13 Jul 2016 16:28:37 -0300
Arnaldo Carvalho de Melo <acme@kernel.org> wrote:

> Em Tue, Jul 12, 2016 at 07:04:54PM +0900, Masami Hiramatsu escreveu:
> > From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> >
> > Make "perf probe --cache --list" shows only available cached events
> > by checking build-id validity.
>
> Something is missing here, I tried following these steps and couldn't
> get to the same results, can you retry them at this point in time, i.e.
> after applying just the three first patches in this series?

Sorry, I missed some steps, see below;

>
> I'm continuing anyway, as I want to check the rest...
>
> - Arnaldo
>
> > E.g. without this patch:
> > ----
> > $ ./perf probe --cache --add oldevent=cmd_probe

Here, you have to change perf source code so that perf binary
build-id is changed.

And make a copy of perf (as perf.old) so that you can get build-id
of both binary.

> > $ make #(to update ./perf)

So, prese ensure that the new perf binary has different build-id.

If both binary has same build-id, you'll see just one cache.

Thank you,

> > $ ./perf probe --cache --add newevent=cmd_probe
> > $ ./perf probe --cache --list
> > /home/mhiramat/ksrc/linux/tools/perf/perf (061e90539bac69
> > probe_perf:newevent=cmd_probe
> > /home/mhiramat/ksrc/linux/tools/perf/perf (c2e44d614e33e1
> > probe_perf:oldevent=cmd_probe
> > ----
> > It shows both of old and new events but user can not use old one.
> > With this;
> > ----
> > $ ./perf probe --cache -l
> > /home/mhiramat/ksrc/linux/tools/perf/perf (061e90539bac69
> > probe_perf:newevent=cmd_probe
> > ----
> > This show only new event which is on the existing binary.
> >
> > Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> > ---
> > Changes in v13:
> > - Instead of the perf-list, apply this change for perf-probe --list
> > because of avoiding to confuse user.
> > Changes in v7:
> > - Validate build-id via sysfs if it is for kallsyms,
> > Changes in v4:
> > - Rename a parameter 'valid' to 'validonly' :)
> > ---
> > tools/perf/builtin-probe.c | 2 +-
> > tools/perf/util/build-id.c | 33 ++++++++++++++++++++++++++++++++-
> > tools/perf/util/build-id.h | 2 +-
> > tools/perf/util/probe-file.c | 2 +-
> > 4 files changed, 35 insertions(+), 4 deletions(-)
> >
> > diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
> > index a1a5cd1..de75af5 100644
> > --- a/tools/perf/builtin-probe.c
> > +++ b/tools/perf/builtin-probe.c
> > @@ -370,7 +370,7 @@ static int del_perf_probe_caches(struct strfilter *filter)
> > struct str_node *nd;
> > int ret;
> >
> > - bidlist = build_id_cache__list_all();
> > + bidlist = build_id_cache__list_all(false);
> > if (!bidlist) {
> > ret = -errno;
> > pr_debug("Failed to get buildids: %d\n", ret);
> > diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
> > index e1a1640..8e86a83 100644
> > --- a/tools/perf/util/build-id.c
> > +++ b/tools/perf/util/build-id.c
> > @@ -206,6 +206,31 @@ out:
> > return ret;
> > }
> >
> > +/* Check if the given build_id cache is valid on current running system */
> > +static bool build_id_cache__valid_id(char *sbuild_id)
> > +{
> > + char real_sbuild_id[SBUILD_ID_SIZE] = "";
> > + char *pathname;
> > + int ret = 0;
> > + bool result = false;
> > +
> > + pathname = build_id_cache__origname(sbuild_id);
> > + if (!pathname)
> > + return false;
> > +
> > + if (!strcmp(pathname, DSO__NAME_KALLSYMS))
> > + ret = sysfs__sprintf_build_id("/", real_sbuild_id);
> > + else if (pathname[0] == '/')
> > + ret = filename__sprintf_build_id(pathname, real_sbuild_id);
> > + else
> > + ret = -EINVAL; /* Should we support other special DSO cache? */
> > + if (ret >= 0)
> > + result = (strcmp(sbuild_id, real_sbuild_id) == 0);
> > + free(pathname);
> > +
> > + return result;
> > +}
> > +
> > static const char *build_id_cache__basename(bool is_kallsyms, bool is_vdso)
> > {
> > return is_kallsyms ? "kallsyms" : (is_vdso ? "vdso" : "elf");
> > @@ -433,13 +458,17 @@ static bool lsdir_bid_tail_filter(const char *name __maybe_unused,
> > return (i == SBUILD_ID_SIZE - 3) && (d->d_name[i] == '\0');
> > }
> >
> > -struct strlist *build_id_cache__list_all(void)
> > +struct strlist *build_id_cache__list_all(bool validonly)
> > {
> > struct strlist *toplist, *linklist = NULL, *bidlist;
> > struct str_node *nd, *nd2;
> > char *topdir, *linkdir = NULL;
> > char sbuild_id[SBUILD_ID_SIZE];
> >
> > + /* for filename__ functions */
> > + if (validonly)
> > + symbol__init(NULL);
> > +
> > /* Open the top-level directory */
> > if (asprintf(&topdir, "%s/.build-id/", buildid_dir) < 0)
> > return NULL;
> > @@ -470,6 +499,8 @@ struct strlist *build_id_cache__list_all(void)
> > if (snprintf(sbuild_id, SBUILD_ID_SIZE, "%s%s",
> > nd->s, nd2->s) != SBUILD_ID_SIZE - 1)
> > goto err_out;
> > + if (validonly && !build_id_cache__valid_id(sbuild_id))
> > + continue;
> > if (strlist__add(bidlist, sbuild_id) < 0)
> > goto err_out;
> > }
> > diff --git a/tools/perf/util/build-id.h b/tools/perf/util/build-id.h
> > index b742e27..64e740f 100644
> > --- a/tools/perf/util/build-id.h
> > +++ b/tools/perf/util/build-id.h
> > @@ -34,7 +34,7 @@ char *build_id_cache__origname(const char *sbuild_id);
> > char *build_id_cache__linkname(const char *sbuild_id, char *bf, size_t size);
> > char *build_id_cache__cachedir(const char *sbuild_id, const char *name,
> > bool is_kallsyms, bool is_vdso);
> > -struct strlist *build_id_cache__list_all(void);
> > +struct strlist *build_id_cache__list_all(bool validonly);
> > int build_id_cache__list_build_ids(const char *pathname,
> > struct strlist **result);
> > bool build_id_cache__cached(const char *sbuild_id);
> > diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> > index b642d06..b062545 100644
> > --- a/tools/perf/util/probe-file.c
> > +++ b/tools/perf/util/probe-file.c
> > @@ -806,7 +806,7 @@ int probe_cache__show_all_caches(struct strfilter *filter)
> > pr_debug("list cache with filter: %s\n", buf);
> > free(buf);
> >
> > - bidlist = build_id_cache__list_all();
> > + bidlist = build_id_cache__list_all(true);
> > if (!bidlist) {
> > pr_debug("Failed to get buildids: %d\n", errno);
> > return -EINVAL;

--
Masami Hiramatsu <mhiramat@kernel.org>