Em Thu, Jun 08, 2017 at 10:40:44AM +0200, Thomas Richter escreveu: > On s390 the counter and sampling facility do not support a > precise IP skid level and sometimes returns EOPNOTSUPP when > structure member precise_ip in struct perf_event_attr > is not set to zero. > > On s390 commnd 'perf record -- true' fails with error EOPNOTSUPP. > This happens only when no events are specified on command line. > > The functions called are > ... > --> perf_evlist__add_default > --> perf_evsel__new_cycles > --> perf_event_attr__set_max_precise_ip > > The last function determines the value of structure member precise_ip > by invoking the perf_event_open() system call and checking the return code. > The first successful open is the value for precise_ip. > However the value is determined without setting member sample_period > and indicates no sampling. > On s390 the counter facility and sampling facility are different. > The above procedure determines a precise_ip value of 3 using the > counter facility. Later it uses the sampling facility with a value of 3 > and fails with EOPNOTSUPP. > > Fix this by changing function perf_evsel__new_cycles(). It is called > very early in the event setup. Delay the determination of > the value of precise_ip until the context is known. This is the case > when perf_evsel__config() is called. > Function perf_evsel__new_cycles() just marks precise_ip to be > determined later. > > Also change the modifier to 'P' for maximum detected precise level. This "Also" usually indicates that you are folding two changes into one patch, please break it into two, and also send it to the perf maintainers, I try to follow linux-perf-users, but you'll get usually faster patch processing if you send to whoever is listed in MAINTAINERS. - Arnaldo > Suggested-by: Hendrik Brueckner <brueckner@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Thomas Richter <tmricht@xxxxxxxxxxxxxxxxxx> > Reviewed-by: Hendrik Brueckner <brueckner@xxxxxxxxxxxxxxxxxx> > --- > tools/perf/util/evsel.c | 7 +++---- > 1 files changed, 3 insertions(+), 4 deletions(-) > > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c > index ac59710..9266908 100644 > --- a/tools/perf/util/evsel.c > +++ b/tools/perf/util/evsel.c > @@ -264,15 +264,14 @@ struct perf_evsel *perf_evsel__new_cycles(void) > > event_attr_init(&attr); > > - perf_event_attr__set_max_precise_ip(&attr); > - > evsel = perf_evsel__new(&attr); > if (evsel == NULL) > goto out; > > + evsel->precise_max = 1; > + > /* use asprintf() because free(evsel) assumes name is allocated */ > - if (asprintf(&evsel->name, "cycles%.*s", > - attr.precise_ip ? attr.precise_ip + 1 : 0, ":ppp") < 0) > + if (asprintf(&evsel->name, "cycles:P") < 0) > goto error_free; > out: > return evsel; > -- > 2.9.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-perf-users" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
