On Mon, 2013-06-03 at 11:02 +0300, Eliezer Tamir wrote: > A very naive select/poll busy-poll support. > Add busy-polling to sock_poll(). > When poll/select have nothing to report, call the low-level > sock_poll() again untill we are out of time or we find something. > Rigth now we poll every socket once, this is subpotimal > but impoves latency when the number of sockets polled is not large. > > Signed-off-by: Alexander Duyck <[email protected]> > Signed-off-by: Jesse Brandeburg <[email protected]> > Tested-by: Willem de Bruijn <[email protected]> > Signed-off-by: Eliezer Tamir <[email protected]> > --- > > fs/select.c | 7 +++++++ > net/socket.c | 10 +++++++++- > 2 files changed, 16 insertions(+), 1 deletions(-) > > diff --git a/fs/select.c b/fs/select.c > index 8c1c96c..f116bf0 100644 > --- a/fs/select.c > +++ b/fs/select.c > @@ -27,6 +27,7 @@ > #include <linux/rcupdate.h> > #include <linux/hrtimer.h> > #include <linux/sched/rt.h> > +#include <net/ll_poll.h> > > #include <asm/uaccess.h> > > @@ -400,6 +401,7 @@ int do_select(int n, fd_set_bits *fds, struct timespec > *end_time) > poll_table *wait; > int retval, i, timed_out = 0; > unsigned long slack = 0; > + cycles_t ll_time = ll_end_time(); > > rcu_read_lock(); > retval = max_select_fd(n, fds); > @@ -486,6 +488,8 @@ int do_select(int n, fd_set_bits *fds, struct timespec > *end_time) > break; > } > > + if (can_poll_ll(ll_time)) > + continue; > /* > * If this is the first loop and we have a timeout > * given, then we convert to ktime_t and set the to > @@ -750,6 +754,7 @@ static int do_poll(unsigned int nfds, struct poll_list > *list, > ktime_t expire, *to = NULL; > int timed_out = 0, count = 0; > unsigned long slack = 0; > + cycles_t ll_time = ll_end_time(); > > /* Optimise the no-wait case */ > if (end_time && !end_time->tv_sec && !end_time->tv_nsec) { > @@ -795,6 +800,8 @@ static int do_poll(unsigned int nfds, struct poll_list > *list, > if (count || timed_out) > break; > > + if (can_poll_ll(ll_time)) > + continue; > /* > * If this is the first loop and we have a timeout > * given, then we convert to ktime_t and set the to > diff --git a/net/socket.c b/net/socket.c > index 721f4e7..02d0e15 100644 > --- a/net/socket.c > +++ b/net/socket.c > @@ -1148,13 +1148,21 @@ EXPORT_SYMBOL(sock_create_lite); > /* No kernel lock held - perfect */ > static unsigned int sock_poll(struct file *file, poll_table *wait) > { > + unsigned int poll_result; > struct socket *sock; > > /* > * We can't return errors to poll, so it's either yes or no. > */ > sock = file->private_data; > - return sock->ops->poll(file, sock, wait); > + > + poll_result = sock->ops->poll(file, sock, wait); > + > + if (!(poll_result & (POLLRDNORM | POLLERR | POLLRDHUP | POLLHUP)) && > + sk_valid_ll(sock->sk) && sk_poll_ll(sock->sk, 1)) > + poll_result = sock->ops->poll(file, sock, NULL); > + > + return poll_result; > } > > static int sock_mmap(struct file *file, struct vm_area_struct *vma) >
In fact, for TCP, POLLOUT event being ready can also be triggered by incoming messages, as the ACK might allow the user application to push more data in the write queue. And you might check wait->_key to avoid testing flags that user is not interested into. ------------------------------------------------------------------------------ Get 100% visibility into Java/.NET code with AppDynamics Lite It's a free troubleshooting tool designed for production Get down to code-level detail for bottlenecks, with <2% overhead. Download for free and get started troubleshooting in minutes. http://p.sf.net/sfu/appdyn_d2d_ap2 _______________________________________________ E1000-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/e1000-devel To learn more about Intel® Ethernet, visit http://communities.intel.com/community/wired
