| Message ID | 1592590409-35439-1-git-send-email-sridhar.samudrala@intel.com |
|---|---|
| State | Not Applicable |
| Delegated to: | David Miller |
| Headers | show |
| Series | fs/epoll: Enable non-blocking busypoll with epoll timeout of 0 | expand |
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@intel.com> > --- > 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) { > + ep_busy_loop(ep, timed_out); > + write_lock_irq(&ep->lock); > + eavail = ep_events_available(ep); > + write_unlock_irq(&ep->lock); > + } > + > goto send_events; > } > >
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@intel.com> >> --- >> 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)) { >> + ep_busy_loop(ep, timed_out); >> + write_lock_irq(&ep->lock); >> + eavail = ep_events_available(ep); >> + write_unlock_irq(&ep->lock); >> + } >> + >> goto send_events; >> } >>
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@intel.com> >>> --- >>> 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; >>> } >>>
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) { + ep_busy_loop(ep, timed_out); + write_lock_irq(&ep->lock); + eavail = ep_events_available(ep); + write_unlock_irq(&ep->lock); + } + goto send_events; }
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@intel.com> --- fs/eventpoll.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)