On 6/24/2020 9:49 AM, Eric Dumazet wrote:
On 6/24/20 9:32 AM, Samudrala, Sridhar wrote:
Adding Dave, Eric for review and see if we can get this in via net-next
as this is mainly useful for networking workloads doing busypoll.
Thanks
Sridhar
On 6/19/2020 11:13 AM, Sridhar Samudrala wrote:
This patch triggers non-blocking busy poll when busy_poll is enabled and
epoll is called with a timeout of 0 and is associated with a napi_id.
This enables an app thread to go through napi poll routine once by calling
epoll with a 0 timeout.
poll/select with a 0 timeout behave in a similar manner.
Signed-off-by: Sridhar Samudrala <sridhar.samudrala@xxxxxxxxx>
---
fs/eventpoll.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 12eebcdea9c8..5f55078d6381 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1847,6 +1847,19 @@ static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
eavail = ep_events_available(ep);
write_unlock_irq(&ep->lock);
+ /*
+ * Trigger non-blocking busy poll if timeout is 0 and there are
+ * no events available. Passing timed_out(1) to ep_busy_loop
+ * will make sure that busy polling is triggered only once and
+ * only if sysctl.net.core.busy_poll is set to non-zero value.
+ */
+ if (!eavail) {
Maybe avoid all this stuff for the typical case of busy poll being not used ?
if (!evail && net_busy_loop_on)) {
Sure. will submit a v2 with this change.
+ ep_busy_loop(ep, timed_out);
+ write_lock_irq(&ep->lock);
+ eavail = ep_events_available(ep);
+ write_unlock_irq(&ep->lock);
+ }
+
goto send_events;
}
