Messages in this thread Patch in this message | | | Date | Thu, 18 Feb 2021 10:20:53 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH] perf record: Fix continue profiling after draining the buffer |
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Em Fri, Feb 05, 2021 at 11:46:12AM +0100, Jiri Olsa escreveu: > On Fri, Feb 05, 2021 at 07:35:22PM +0900, Namhyung Kim wrote: > > Hello, > > > > On Fri, Feb 5, 2021 at 3:50 PM Yang Jihong <yangjihong1@huawei.com> wrote: > > > > > > commit da231338ec9c098707c8a1e4d8a50e2400e2fe17 uses eventfd to solve rare race > > > where the setting and checking of 'done' which add done_fd to pollfd. > > > When draining buffer, revents of done_fd is 0 and evlist__filter_pollfd > > > function returns a non-zero value. > > > As a result, perf record does not stop profiling. > > > > > > The following simple scenarios can trigger this condition: > > > > > > sleep 10 & > > > perf record -p $! > > > > > > After the sleep process exits, perf record should stop profiling and exit. > > > However, perf record keeps running. > > > > > > If pollfd revents contains only POLLERR or POLLHUP, > > > perf record indicates that buffer is draining and need to stop profiling. > > > Use fdarray_flag__nonfilterable to set done eventfd to nonfilterable objects, > > > so that evlist__filter_pollfd does not filter and check done eventfd. > > > > > > Fixes: da231338ec9c (perf record: Use an eventfd to wakeup when done) > > > Signed-off-by: Yang Jihong <yangjihong1@huawei.com> > > > --- > > > tools/perf/builtin-record.c | 2 +- > > > tools/perf/util/evlist.c | 8 ++++++++ > > > tools/perf/util/evlist.h | 4 ++++ > > > 3 files changed, 13 insertions(+), 1 deletion(-) > > > > > > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c > > > index fd3911650612..51e593e896ea 100644 > > > --- a/tools/perf/builtin-record.c > > > +++ b/tools/perf/builtin-record.c > > > @@ -1663,7 +1663,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv) > > > status = -1; > > > goto out_delete_session; > > > } > > > - err = evlist__add_pollfd(rec->evlist, done_fd); > > > + err = evlist__add_wakeup_eventfd(rec->evlist, done_fd); > > > if (err < 0) { > > > pr_err("Failed to add wakeup eventfd to poll list\n"); > > > status = err; > > > diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c > > > index 05363a7247c4..fea4c1e8010d 100644 > > > --- a/tools/perf/util/evlist.c > > > +++ b/tools/perf/util/evlist.c > > > @@ -572,6 +572,14 @@ int evlist__filter_pollfd(struct evlist *evlist, short revents_and_mask) > > > return perf_evlist__filter_pollfd(&evlist->core, revents_and_mask); > > > } > > > > > > +#ifdef HAVE_EVENTFD_SUPPORT > > > +int evlist__add_wakeup_eventfd(struct evlist *evlist, int fd) > > > +{ > > > + return perf_evlist__add_pollfd(&evlist->core, fd, NULL, POLLIN, > > > + fdarray_flag__nonfilterable); > > > +} > > > +#endif > > > > Does it build when HAVE_EVENTFD_SUPPORT is not defined? > > yea, I was wondering the same.. but it's called only from > code within HAVE_EVENTFD_SUPPORT ifdef
Yes, this can't work on systems without eventfd, it will simply not build, and why do we have to make the definition of this function conditional on HAVE_EVENTFD_SUPPORT?
I'm missing something :-\
Yeah, this whole call to evlist__add_pollfd is already surrounded by #ifdef HAVE_EVENTFD_SUPPORT:
1656 if (zstd_init(&session->zstd_data, rec->opts.comp_level) < 0) { 1657 pr_err("Compression initialization failed.\n"); 1658 return -1; 1659 } 1660 #ifdef HAVE_EVENTFD_SUPPORT 1661 done_fd = eventfd(0, EFD_NONBLOCK); 1662 if (done_fd < 0) { 1663 pr_err("Failed to create wakeup eventfd, error: %m\n"); 1664 status = -1; 1665 goto out_delete_session; 1666 } 1667 err = evlist__add_pollfd(rec->evlist, done_fd); 1668 if (err < 0) { 1669 pr_err("Failed to add wakeup eventfd to poll list\n"); 1670 status = err; 1671 goto out_delete_session; 1672 } 1673 #endif // HAVE_EVENTFD_SUPPORT 1674 1675 session->header.env.comp_type = PERF_COMP_ZSTD; 1676 session->header.env.comp_level = rec->opts.comp_level;
Jiri, does your Acked-by stands? Namhyung?
- Arnaldo > jirka > > > > > Thanks, > > Namhyung > > > > > > > + > > > int evlist__poll(struct evlist *evlist, int timeout) > > > { > > > return perf_evlist__poll(&evlist->core, timeout); > > > diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h > > > index 1aae75895dea..6d4d62151bc8 100644 > > > --- a/tools/perf/util/evlist.h > > > +++ b/tools/perf/util/evlist.h > > > @@ -142,6 +142,10 @@ struct evsel *evlist__find_tracepoint_by_name(struct evlist *evlist, const char > > > int evlist__add_pollfd(struct evlist *evlist, int fd); > > > int evlist__filter_pollfd(struct evlist *evlist, short revents_and_mask); > > > > > > +#ifdef HAVE_EVENTFD_SUPPORT > > > +int evlist__add_wakeup_eventfd(struct evlist *evlist, int fd); > > > +#endif > > > + > > > int evlist__poll(struct evlist *evlist, int timeout); > > > > > > struct evsel *evlist__id2evsel(struct evlist *evlist, u64 id); > > > -- > > > 2.17.1 > > > > > >
--
- Arnaldo
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