Messages in this thread | | | Date | Tue, 12 May 2020 14:12:32 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH] perf record: Use an eventfd to wakeup when done |
| |
On Tue, May 12, 2020 at 02:59:36PM +1000, Anand K Mistry wrote:
SNIP
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c > index 1ab349abe90469..099ecaa66732a2 100644 > --- a/tools/perf/builtin-record.c > +++ b/tools/perf/builtin-record.c > @@ -53,6 +53,7 @@ > #include <unistd.h> > #include <sched.h> > #include <signal.h> > +#include <sys/eventfd.h> > #include <sys/mman.h> > #include <sys/wait.h> > #include <sys/types.h> > @@ -518,15 +519,28 @@ static int record__pushfn(struct mmap *map, void *to, void *bf, size_t size) > > static volatile int signr = -1; > static volatile int child_finished; > +static int done_fd = -1; > > static void sig_handler(int sig) > { > + u64 tmp = 1; > if (sig == SIGCHLD) > child_finished = 1; > else > signr = sig; > > done = 1; > + > + /* > + * It is possible for this signal handler to run after done is checked > + * in the main loop, but before the perf counter fds are polled. If this > + * happens, the poll() will continue to wait even though done is set, > + * and will only break out if either another signal is received, or the > + * counters are ready for read. To ensure the poll() doesn't sleep when > + * done is set, use an eventfd (done_fd) to wake up the poll(). > + */ > + if (write(done_fd, &tmp, sizeof(tmp)) < 0) > + pr_err("failed to signal wakeup fd\n"); > } > > static void sigsegv_handler(int sig) > @@ -1424,6 +1438,17 @@ static int __cmd_record(struct record *rec, int argc, const char **argv) > int fd; > float ratio = 0; > > + done_fd = eventfd(0, EFD_NONBLOCK); > + if (done_fd < 0) { > + pr_err("Failed to create wakeup eventfd, error: %m\n"); > + return -1; > + } > + err = evlist__add_pollfd(rec->evlist, done_fd); > + if (err < 0) { > + pr_err("Failed to add wakeup eventfd to poll list\n"); > + return -1; > + }
sorry I did not notice before, but I think we also need to close done_fd descriptor on the exit path
also please change subject to PATCHv3 for the next version
thanks, jirka
> + > atexit(record__sig_exit); > signal(SIGCHLD, sig_handler); > signal(SIGINT, sig_handler); > -- > 2.26.2.645.ge9eca65c58-goog >
| |