| Message ID | 1594447781-27115-1-git-send-email-sridhar.samudrala@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v4] fs/epoll: Enable non-blocking busypoll when epoll timeout is 0 | expand |
On Fri, Jul 10, 2020 at 11:13 PM Sridhar Samudrala <sridhar.samudrala@intel.com> wrote: > > This patch triggers non-blocking busy poll when busy_poll is enabled, > 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@intel.com> > > v4: > - Fix a typo (Andy) > v3: > - reset napi_id if no event available after busy poll (Alex) > v2: > - Added net_busy_loop_on() check (Eric) > --- > fs/eventpoll.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/fs/eventpoll.c b/fs/eventpoll.c > index 12eebcdea9c8..10da7a8e1c2b 100644 > --- a/fs/eventpoll.c > +++ b/fs/eventpoll.c > @@ -1847,6 +1847,22 @@ 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. > + */ > + if (!eavail && net_busy_loop_on()) { > + ep_busy_loop(ep, timed_out); > + > + write_lock_irq(&ep->lock); > + eavail = ep_events_available(ep); > + write_unlock_irq(&ep->lock); > + > + if (!eavail) > + ep_reset_busy_poll_napi_id(ep); > + } > + > goto send_events; > } > This addresses the concern that I had. Reviewed-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 12eebcdea9c8..10da7a8e1c2b 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1847,6 +1847,22 @@ 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. + */ + if (!eavail && net_busy_loop_on()) { + ep_busy_loop(ep, timed_out); + + write_lock_irq(&ep->lock); + eavail = ep_events_available(ep); + write_unlock_irq(&ep->lock); + + if (!eavail) + ep_reset_busy_poll_napi_id(ep); + } + goto send_events; }
This patch triggers non-blocking busy poll when busy_poll is enabled, 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@intel.com> v4: - Fix a typo (Andy) v3: - reset napi_id if no event available after busy poll (Alex) v2: - Added net_busy_loop_on() check (Eric) --- fs/eventpoll.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)