timeval: Remove backtrace feature.

The backtrace feature of timeval is useful because it provides a "poor
man's profile" view of Open vSwitch.  But it is not likely to be useful in
a multithreaded process, because signal delivery doesn't necessarily follow
the profile when there is more than one thread.  (A signal in a
multithreaded process are delivered to an arbitrary thread.)

Another problem with the backtrace feature is that it is difficult for
format_backtraces() to synchronize properly with the signal handler in a
multithreaded process.  In a single-threaded process, it can just block
the signal handler, but in a multithreaded process this does not prevent
signal delivery to threads other than the one running format_backtrace().

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ed Maste <emaste@freebsd.org>

1 files changed, 0 insertions, 6 deletions

diff --git a/lib/poll-loop.c b/lib/poll-loop.c
index ea00d265a..5f4b16c84 100644
--- a/lib/poll-loop.c
+++ b/lib/poll-loop.c
@@ -156,7 +156,6 @@ poll_immediate_wake(const char *where)
 static void
 log_wakeup(const char *where, const struct pollfd *pollfd, int timeout)
 {
-    static struct vlog_rate_limit trace_rl = VLOG_RATE_LIMIT_INIT(1, 1);
     static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(10, 10);
     enum vlog_level level;
     int cpu_usage;
@@ -200,11 +199,6 @@ log_wakeup(const char *where, const struct pollfd *pollfd, int timeout)
     }
     if (cpu_usage >= 0) {
         ds_put_format(&s, " (%d%% CPU usage)", cpu_usage);
-
-        if (!vlog_should_drop(THIS_MODULE, level, &trace_rl)) {
-            ds_put_char(&s, '\n');
-            format_backtraces(&s, 2);
-        }
     }
     VLOG(level, "%s", ds_cstr(&s));
     ds_destroy(&s);