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

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Fri, Jul 01, 2016 at 05:03:12PM +0900, Masami Hiramatsu escreveu:
> From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> 
> 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@hitachi.com>
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
>  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