[incubator-nuttx] branch master updated: tcp_netpoll.c: Fix a performance issue with CONFIG_NET_TCP_WRITE_BUFFERS

[xi...@apache.org]

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xiaoxiang pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/incubator-nuttx.git


The following commit(s) were added to refs/heads/master by this push:
     new acc3596  tcp_netpoll.c: Fix a performance issue with CONFIG_NET_TCP_WRITE_BUFFERS
acc3596 is described below

commit acc3596adc919ec63a443e4a37133ef51bed68e4
Author: YAMAMOTO Takashi <ya...@midokura.com>
AuthorDate: Mon Apr 5 16:21:17 2021 +0900

    tcp_netpoll.c: Fix a performance issue with CONFIG_NET_TCP_WRITE_BUFFERS
    
    Tested with a modified version of webclient, which uses non-blocking i/o.
    The packet dumps look more reasonable with this change.
---
 net/tcp/tcp_netpoll.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/net/tcp/tcp_netpoll.c b/net/tcp/tcp_netpoll.c
index 505eef8..03ffe0f 100644
--- a/net/tcp/tcp_netpoll.c
+++ b/net/tcp/tcp_netpoll.c
@@ -97,7 +97,18 @@ static uint16_t tcp_poll_eventhandler(FAR struct net_driver_s *dev,
 
       /* A poll is a sign that we are free to send data. */
 
-      else if (psock_tcp_cansend(info->psock) >= 0)
+      /* Wake up poll() speculatively on TCP_ACKDATA.
+       * Note: our event handler is usually executed before
+       * psock_send_eventhandler, which might free IOBs/WRBs on TCP_ACKDATA.
+       * Revisit: consider some kind of priority for devif callback to allow
+       * this callback to be inserted after psock_send_eventhandler.
+       */
+
+      else if (psock_tcp_cansend(info->psock) >= 0
+#if defined(CONFIG_NET_TCP_WRITE_BUFFERS)
+               || (flags & TCP_ACKDATA) != 0
+#endif
+              )
         {
           eventset |= (POLLOUT & info->fds->events);
         }
@@ -198,7 +209,11 @@ int tcp_pollsetup(FAR struct socket *psock, FAR struct pollfd *fds)
 
   if ((fds->events & POLLOUT) != 0)
     {
-      cb->flags |= TCP_POLL;
+      cb->flags |= TCP_POLL
+#if defined(CONFIG_NET_TCP_WRITE_BUFFERS)
+                   | TCP_ACKDATA
+#endif
+                   ;
     }
 
   if ((fds->events & POLLIN) != 0)