linux-kernel - Re: [PATCH perf/core v11 07/20] perf probe: Add --cache option to cache the probe definitions

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Date:	Thu, 16 Jun 2016 06:38:30 +0900
From:	Masami Hiramatsu <mhiramat@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	linux-kernel@...r.kernel.org, Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	Hemant Kumar <hemant@...ux.vnet.ibm.com>,
	Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
	Brendan Gregg <brendan.d.gregg@...il.com>
Subject: Re: [PATCH perf/core v11 07/20] perf probe: Add --cache option to
 cache the probe definitions

On Wed, 15 Jun 2016 14:38:59 -0300
Arnaldo Carvalho de Melo <acme@...nel.org> wrote:

> Em Wed, Jun 15, 2016 at 12:28:40PM +0900, Masami Hiramatsu escreveu:
> > From: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> > 
> > Add --cache option to cache the probe definitions. This
> > just saves the result of the dwarf analysis to probe cache.
> 
> So, I applied up to this patch and will test build and send to Ingo
> today, but from this point on I think you should provide usage examples,
> i.e. use the options introduced, showing what effects it has on
> the cache, etc.

Hmm, OK, I'll add that on perf-probe.txt, but anyway, unless [8/23]
perf probe just write events in cache files, but not reuse (read)
the cache entries. IOW, it would be just a waste of disk space....

Thank you,

> 
> - Arnaldo
>  
> > Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> > Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> > ---
> >  Changes in v11:
> >   - Check failure of probe_cache operations and warn it.
> >  Changes in v10:
> >   - Split into 5 subpatches.
> >  Changes in v6:
> >   - Remove unneeded O_APPEND from open(). (Thanks Namhyung!)
> >   - Fix to check the return value of probe_cache_entry__new and strdup.(ditto)
> >  Changes in v5:
> >   - Move probe_cache* definitions. (code cleanup)
> > 
> >  Changes in v4:
> >   - Remove cache saving failure message.
> > ---
> >  tools/perf/Documentation/perf-probe.txt |    4 ++++
> >  tools/perf/builtin-probe.c              |    1 +
> >  tools/perf/util/probe-event.c           |    9 +++++++++
> >  tools/perf/util/probe-event.h           |    1 +
> >  4 files changed, 15 insertions(+)
> > 
> > diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt
> > index 3a8a9ba..947db6f 100644
> > --- a/tools/perf/Documentation/perf-probe.txt
> > +++ b/tools/perf/Documentation/perf-probe.txt
> > @@ -109,6 +109,10 @@ OPTIONS
> >  	Dry run. With this option, --add and --del doesn't execute actual
> >  	adding and removal operations.
> >  
> > +--cache::
> > +	Cache the probes (with --add option). Any events which successfully added
> > +	are also stored in the cache file.
> > +
> >  --max-probes=NUM::
> >  	Set the maximum number of probe points for an event. Default is 128.
> >  
> > diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
> > index 9af859b..6d7ab431 100644
> > --- a/tools/perf/builtin-probe.c
> > +++ b/tools/perf/builtin-probe.c
> > @@ -512,6 +512,7 @@ __cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
> >  		    "Enable symbol demangling"),
> >  	OPT_BOOLEAN(0, "demangle-kernel", &symbol_conf.demangle_kernel,
> >  		    "Enable kernel symbol demangling"),
> > +	OPT_BOOLEAN(0, "cache", &probe_conf.cache, "Manipulate probe cache"),
> >  	OPT_END()
> >  	};
> >  	int ret;
> > diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> > index cbc8a8b..084756c 100644
> > --- a/tools/perf/util/probe-event.c
> > +++ b/tools/perf/util/probe-event.c
> > @@ -2514,6 +2514,7 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
> >  {
> >  	int i, fd, ret;
> >  	struct probe_trace_event *tev = NULL;
> > +	struct probe_cache *cache = NULL;
> >  	struct strlist *namelist;
> >  
> >  	fd = probe_file__open(PF_FL_RW | (pev->uprobes ? PF_FL_UPROBE : 0));
> > @@ -2555,6 +2556,14 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
> >  	}
> >  	if (ret == -EINVAL && pev->uprobes)
> >  		warn_uprobe_event_compat(tev);
> > +	if (ret == 0 && probe_conf.cache) {
> > +		cache = probe_cache__new(pev->target);
> > +		if (!cache ||
> > +		    probe_cache__add_entry(cache, pev, tevs, ntevs) < 0 ||
> > +		    probe_cache__commit(cache) < 0)
> > +			pr_warning("Failed to add event to probe cache\n");
> > +		probe_cache__delete(cache);
> > +	}
> >  
> >  	strlist__delete(namelist);
> >  close_out:
> > diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
> > index 0b024ba..432b690 100644
> > --- a/tools/perf/util/probe-event.h
> > +++ b/tools/perf/util/probe-event.h
> > @@ -12,6 +12,7 @@ struct probe_conf {
> >  	bool	show_location_range;
> >  	bool	force_add;
> >  	bool	no_inlines;
> > +	bool	cache;
> >  	int	max_probes;
> >  };
> >  extern struct probe_conf probe_conf;


-- 
Masami Hiramatsu <mhiramat@...nel.org>