Re: [PATCH] perf bench: add benchmark for evlist open/close operations
From: Riccardo Mancini
Date: Tue Aug 10 2021 - 06:32:02 EST
Hi Arnaldo,
On Mon, 2021-08-09 at 17:28 -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Aug 09, 2021 at 05:23:31PM -0300, Arnaldo Carvalho de Melo escreveu:
> > Em Mon, Aug 09, 2021 at 10:11:02PM +0200, Riccardo Mancini escreveu:
> > > +static struct evlist *bench__create_evlist(char *evstr)
> > > +{
> > > + struct evlist *evlist;
> > > + struct parse_events_error err;
> > > + int ret;
>
> > > + evlist = evlist__new();
> > > + if (!evlist) {
> > > + pr_err("Not enough memory to create evlist\n");
> > > + return NULL;
> > > + }
>
> > > + bzero(&err, sizeof(err));
>
> > man bzero
> >
> > The bzero() function is deprecated (marked as LEGACY in POSIX.1-2001);
> > use memset(3) in new programs. POSIX.1-2008 removes the specification of
> > bzero(). The bzero() function first appeared in 4.3BSD.
Oops, I didn't know, but I saw it is being used in some parts in perf, maybe we
should get rid of them:
$ rg -c bzero
builtin-lock.c:1
arch/powerpc/util/kvm-stat.c:1
builtin-stat.c:1
builtin-trace.c:2
bench/evlist-open-close.c:1
bench/numa.c:5
tests/parse-events.c:1
tests/backward-ring-buffer.c:1
tests/bpf.c:2
util/metricgroup.c:1
util/parse-events.c:1
>
> > I'm replacing it with a memset().
>
> This one is also equivalent:
>
> tools/perf/tests/pmu-events.c: struct parse_events_error error = { .idx = 0, };
>
> https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html
>
> That text is a bit roundabout, as it says that the members that are not
> explicitely initialized will be initialized as variables with static
> storage duration, i.e. zeroed.
Would it be the same doing the shorter {0}. It would be a general solution for
these init-to-zero cases.
Unrelated to this small issue, I noticed I forgot to check the return of
bench__create_evlist. Would you like me to send a v2 fixing both issues or are
you able to apply this other small change yourself?
diff --git a/tools/perf/bench/evlist-open-close.c b/tools/perf/bench/evlist-open-close.c
index 40bce06f5ca7bef3..f0b9c330f34f2984 100644
--- a/tools/perf/bench/evlist-open-close.c
+++ b/tools/perf/bench/evlist-open-close.c
@@ -168,7 +168,11 @@ static int bench_evlist_open_close__run(char *evstr)
for (i = 0; i < iterations; i++) {
pr_debug("Started iteration %d\n", i);
+
evlist = bench__create_evlist(evstr);
+ if (!evlist)
+ return -ENOMEM;
+
gettimeofday(&start, NULL);
err = bench__do_evlist_open_close(evlist);
if (err) {
Thanks,
Riccardo
>
> - Arnaldo