Messages in this thread | | | Date | Thu, 18 Feb 2021 14:09:40 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH] perf record: Fix continue profiling after draining the buffer |
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Em Thu, Feb 18, 2021 at 10:20:53AM -0300, Arnaldo Carvalho de Melo escreveu: > 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?
Thanks tested and applied, together with Jiri's Tested-by,
- Arnaldo
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