From: Anton Ivanov <[email protected]>
If we are not obtaining any useful information out of the poll(),
such as is a fd busy or not, we do not need to do a poll() if
an immediate_wake() has been requested.
This cuts out all the pollfd hash additions, forming the poll
arguments and the actual poll() after a call to
poll_immediate_wake()
Signed-off-by: Anton Ivanov <[email protected]>
---
lib/poll-loop.c | 69 ++++++++++++++++++++++++++++++++-----------------
lib/timeval.c | 11 +++++++-
2 files changed, 56 insertions(+), 24 deletions(-)
diff --git a/lib/poll-loop.c b/lib/poll-loop.c
index 4e751ff2c..09bc4f5c4 100644
--- a/lib/poll-loop.c
+++ b/lib/poll-loop.c
@@ -53,6 +53,7 @@ struct poll_loop {
* wake up immediately, or LLONG_MAX to wait forever. */
long long int timeout_when; /* In msecs as returned by time_msec(). */
const char *timeout_where; /* Where 'timeout_when' was set. */
+ bool immediate_wake;
};
static struct poll_loop *poll_loop(void);
@@ -107,6 +108,13 @@ poll_create_node(int fd, HANDLE wevent, short int events,
const char *where)
COVERAGE_INC(poll_create_node);
+ if (loop->immediate_wake) {
+ /* We have been asked to bail out of this poll loop.
+ * There is no point to engage in yack shaving a poll hmap.
+ */
+ return;
+ }
+
/* Both 'fd' and 'wevent' cannot be set. */
ovs_assert(!fd != !wevent);
@@ -181,8 +189,15 @@ poll_wevent_wait_at(HANDLE wevent, const char *where)
void
poll_timer_wait_at(long long int msec, const char *where)
{
- long long int now = time_msec();
+ long long int now;
long long int when;
+ struct poll_loop *loop = poll_loop();
+
+ if (loop->immediate_wake) {
+ return;
+ }
+
+ now = time_msec();
if (msec <= 0) {
/* Wake up immediately. */
@@ -229,7 +244,9 @@ poll_timer_wait_until_at(long long int when, const char
*where)
void
poll_immediate_wake_at(const char *where)
{
+ struct poll_loop *loop = poll_loop();
poll_timer_wait_at(0, where);
+ loop->immediate_wake = true;
}
/* Logs, if appropriate, that the poll loop was awakened by an event
@@ -320,10 +337,10 @@ poll_block(void)
{
struct poll_loop *loop = poll_loop();
struct poll_node *node;
- struct pollfd *pollfds;
+ struct pollfd *pollfds = NULL;
HANDLE *wevents = NULL;
int elapsed;
- int retval;
+ int retval = 0;
int i;
/* Register fatal signal events before actually doing any real work for
@@ -335,34 +352,38 @@ poll_block(void)
}
timewarp_run();
- pollfds = xmalloc(hmap_count(&loop->poll_nodes) * sizeof *pollfds);
+ if (!loop->immediate_wake) {
+ pollfds = xmalloc(hmap_count(&loop->poll_nodes) * sizeof *pollfds);
#ifdef _WIN32
- wevents = xmalloc(hmap_count(&loop->poll_nodes) * sizeof *wevents);
+ wevents = xmalloc(hmap_count(&loop->poll_nodes) * sizeof *wevents);
#endif
- /* Populate with all the fds and events. */
- i = 0;
- HMAP_FOR_EACH (node, hmap_node, &loop->poll_nodes) {
- pollfds[i] = node->pollfd;
+ /* Populate with all the fds and events. */
+ i = 0;
+ HMAP_FOR_EACH (node, hmap_node, &loop->poll_nodes) {
+ pollfds[i] = node->pollfd;
#ifdef _WIN32
- wevents[i] = node->wevent;
- if (node->pollfd.fd && node->wevent) {
- short int wsa_events = 0;
- if (node->pollfd.events & POLLIN) {
- wsa_events |= FD_READ | FD_ACCEPT | FD_CLOSE;
- }
- if (node->pollfd.events & POLLOUT) {
- wsa_events |= FD_WRITE | FD_CONNECT | FD_CLOSE;
+ wevents[i] = node->wevent;
+ if (node->pollfd.fd && node->wevent) {
+ short int wsa_events = 0;
+ if (node->pollfd.events & POLLIN) {
+ wsa_events |= FD_READ | FD_ACCEPT | FD_CLOSE;
+ }
+ if (node->pollfd.events & POLLOUT) {
+ wsa_events |= FD_WRITE | FD_CONNECT | FD_CLOSE;
+ }
+ WSAEventSelect(node->pollfd.fd, node->wevent, wsa_events);
}
- WSAEventSelect(node->pollfd.fd, node->wevent, wsa_events);
- }
#endif
- i++;
- }
+ i++;
+ }
- retval = time_poll(pollfds, hmap_count(&loop->poll_nodes), wevents,
- loop->timeout_when, &elapsed);
+ retval = time_poll(pollfds, hmap_count(&loop->poll_nodes), wevents,
+ loop->timeout_when, &elapsed);
+ } else {
+ retval = time_poll(NULL, 0, NULL, loop->timeout_when, &elapsed);
+ }
if (retval < 0) {
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
VLOG_ERR_RL(&rl, "poll: %s", ovs_strerror(-retval));
@@ -381,6 +402,7 @@ poll_block(void)
free_poll_nodes(loop);
loop->timeout_when = LLONG_MAX;
loop->timeout_where = NULL;
+ loop->immediate_wake = false;
free(pollfds);
free(wevents);
@@ -417,6 +439,7 @@ poll_loop(void)
loop = xzalloc(sizeof *loop);
loop->timeout_when = LLONG_MAX;
hmap_init(&loop->poll_nodes);
+ loop->immediate_wake = false;
xpthread_setspecific(key, loop);
}
return loop;
diff --git a/lib/timeval.c b/lib/timeval.c
index 193c7bab1..c6ac87376 100644
--- a/lib/timeval.c
+++ b/lib/timeval.c
@@ -323,7 +323,13 @@ time_poll(struct pollfd *pollfds, int n_pollfds, HANDLE
*handles OVS_UNUSED,
}
#ifndef _WIN32
- retval = poll(pollfds, n_pollfds, time_left);
+ /* Pollfds is NULL only if we are doing a immediate_wake
+ * shortcut. Otherwise there is at least one fd in it for
+ * the signals pipe fd.
+ */
+ if (n_pollfds != 0) {
+ retval = poll(pollfds, n_pollfds, time_left);
+ }
if (retval < 0) {
retval = -errno;
}
@@ -331,6 +337,9 @@ time_poll(struct pollfd *pollfds, int n_pollfds, HANDLE
*handles OVS_UNUSED,
if (n_pollfds > MAXIMUM_WAIT_OBJECTS) {
VLOG_ERR("Cannot handle more than maximum wait objects\n");
} else if (n_pollfds != 0) {
+ /* If we are doing an immediate_wake shortcut n_pollfds is
+ * zero, so we skip the actual call.
+ */
retval = WaitForMultipleObjects(n_pollfds, handles, FALSE,
time_left);
}
