Re: [PATCH perf/core v13 01/15] perf probe: Use cache entry if possible

From: Arnaldo Carvalho de Melo
Date: Fri Jul 01 2016 - 09:20:37 EST

Em Fri, Jul 01, 2016 at 05:03:12PM +0900, Masami Hiramatsu escreveu:
> From: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
>
> Before analyzing debuginfo, try to find a corresponding entry
> from probe cache always. This does not depend on --cache,
> the --cache enables to store/update cache, but looking up
> the cache is always enabled.
>
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
> Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> ---
> Changes in v12:
> - Rename strlist__for_each to strlist__for_each_entry.
>
> Changes in v6:
> - Remove fallback lookup routine by using function name
> as cached event name, because it should be done by following
> patch which supports %cached-event.

cool, keeping the entries for changes for this specific patch helps in
swapping back into my brain the history of this patch, helping in
re-re-re-re-reviewing 8-)

> ---
> tools/perf/util/probe-event.c | 65 ++++++++++++++++++++++++++++++++++++++++-
> tools/perf/util/probe-file.c | 20 ++++++++++++-
> tools/perf/util/probe-file.h | 5 +++
> 3 files changed, 86 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 55f41d5..47b6b8b 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -2474,17 +2474,24 @@ static int probe_trace_event__set_name(struct probe_trace_event *tev,
> char buf[64];
> int ret;
>
> + /* If probe_event or trace_event already have the name, reuse it */
> if (pev->event)
> event = pev->event;
> - else
> + else if (tev->event)
> + event = tev->event;
> + else {
> + /* Or generate new one from probe point */
> if (pev->point.function &&
> (strncmp(pev->point.function, "0x", 2) != 0) &&
> !strisglob(pev->point.function))
> event = pev->point.function;
> else
> event = tev->point.realname;
> + }
> if (pev->group)
> group = pev->group;
> + else if (tev->group)
> + group = tev->group;
> else
> group = PERFPROBE_GROUP;
>
> @@ -2531,7 +2538,7 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
> for (i = 0; i < ntevs; i++) {
> tev = &tevs[i];
> /* Skip if the symbol is out of .text or blacklisted */
> - if (!tev->point.symbol)
> + if (!tev->point.symbol && !pev->uprobes)
> continue;
>
> /* Set new name for tev (and update namelist) */
> @@ -2844,6 +2851,55 @@ errout:
>
> bool __weak arch__prefers_symtab(void) { return false; }
>
> +static int find_probe_trace_events_from_cache(struct perf_probe_event *pev,
> + struct probe_trace_event **tevs)
> +{
> + struct probe_cache *cache;
> + struct probe_cache_entry *entry;
> + struct probe_trace_event *tev;
> + struct str_node *node;
> + int ret, i;
> +
> + cache = probe_cache__new(pev->target);
> + if (!cache)
> + return 0;
> +
> + entry = probe_cache__find(cache, pev);
> + if (!entry) {
> + ret = 0;
> + goto out;
> + }
> +
> + ret = strlist__nr_entries(entry->tevlist);
> + if (ret > probe_conf.max_probes) {
> + pr_debug("Too many entries matched in the cache of %s\n",
> + pev->target ? : "kernel");
> + ret = -E2BIG;
> + goto out;
> + }
> +
> + *tevs = zalloc(ret * sizeof(*tev));
> + if (!*tevs) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + i = 0;
> + strlist__for_each_entry(node, entry->tevlist) {
> + tev = &(*tevs)[i++];
> + ret = parse_probe_trace_command(node->s, tev);
> + if (ret < 0)
> + goto out;
> + /* Set the uprobes attribute as same as original */
> + tev->uprobes = pev->uprobes;
> + }
> + ret = i;
> +
> +out:
> + probe_cache__delete(cache);
> + return ret;
> +}
> +
> static int convert_to_probe_trace_events(struct perf_probe_event *pev,
> struct probe_trace_event **tevs)
> {
> @@ -2866,6 +2922,11 @@ static int convert_to_probe_trace_events(struct perf_probe_event *pev,
> if (ret > 0)
> return ret;
>
> + /* At first, we need to lookup cache entry */
> + ret = find_probe_trace_events_from_cache(pev, tevs);
> + if (ret > 0)
> + return ret; /* Found in probe cache */
> +
> if (arch__prefers_symtab() && !perf_probe_event_need_dwarf(pev)) {
> ret = find_probe_trace_events_from_map(pev, tevs);
> if (ret > 0)
> diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> index 1c12c1a..a94ee47 100644
> --- a/tools/perf/util/probe-file.c
> +++ b/tools/perf/util/probe-file.c
> @@ -524,7 +524,7 @@ static bool streql(const char *a, const char *b)
> return !strcmp(a, b);
> }
>
> -static struct probe_cache_entry *
> +struct probe_cache_entry *
> probe_cache__find(struct probe_cache *pcache, struct perf_probe_event *pev)
> {
> struct probe_cache_entry *entry = NULL;
> @@ -548,6 +548,24 @@ found:
> return entry;
> }
>
> +struct probe_cache_entry *
> +probe_cache__find_by_name(struct probe_cache *pcache,
> + const char *group, const char *event)
> +{
> + struct probe_cache_entry *entry = NULL;
> +
> + list_for_each_entry(entry, &pcache->entries, node) {
> + /* Hit if same event name or same command-string */
> + if (streql(entry->pev.group, group) &&
> + streql(entry->pev.event, event))
> + goto found;
> + }
> + entry = NULL;
> +
> +found:
> + return entry;
> +}
> +
> int probe_cache__add_entry(struct probe_cache *pcache,
> struct perf_probe_event *pev,
> struct probe_trace_event *tevs, int ntevs)
> diff --git a/tools/perf/util/probe-file.h b/tools/perf/util/probe-file.h
> index d872e3d..910aa74 100644
> --- a/tools/perf/util/probe-file.h
> +++ b/tools/perf/util/probe-file.h
> @@ -38,5 +38,8 @@ int probe_cache__add_entry(struct probe_cache *pcache,
> int probe_cache__commit(struct probe_cache *pcache);
> void probe_cache__purge(struct probe_cache *pcache);
> void probe_cache__delete(struct probe_cache *pcache);
> -
> +struct probe_cache_entry *probe_cache__find(struct probe_cache *pcache,
> + struct perf_probe_event *pev);
> +struct probe_cache_entry *probe_cache__find_by_name(struct probe_cache *pcache,
> + const char *group, const char *event);
> #endif