[Ocfs2-devel] o2net_sendpage reviews, thanks

From: Zhangguanghui <zhang.guanghui@h3c.com>
To: ocfs2-devel@oss.oracle.com
Subject: [Ocfs2-devel] o2net_sendpage reviews, thanks
Date: Tue, 30 Jun 2015 03:28:08 +0000	[thread overview]
Message-ID: <2015063011280785381652@h3c.com> (raw)
In-Reply-To: 2015063011180600247349@h3c.com

Hi

1.  In the callback o2net_sendpage -> sendpage()
2.  If sendpage (tcp socket send) continuously returns -EAGAIN, then get into an endless loop,
    even though the function of cond_resched() have already used.
3.  I think it is not reasonable, try to continuously send 20 times returns -EAGAIN ,
    shutdown the socket to avoid affecting the entire cluster.

Finally, any feedback about this process (positive or negative) would be greatly appreciated.

--- tcp.c       2015-06-30 11:46:54.727447919 +0800
+++ tcp.c.diff  2015-06-30 11:52:12.823447881 +0800
@@ -949,6 +949,7 @@
 {
        struct o2net_node *nn = o2net_nn_from_num(sc->sc_node->nd_num);
        ssize_t ret;
+       int send_fails = 20;

        while (1) {
                mutex_lock(&sc->sc_send_lock);
@@ -959,10 +960,11 @@
                mutex_unlock(&sc->sc_send_lock);
                if (ret == size)
                        break;
-               if (ret == (ssize_t)-EAGAIN) {
+               if (ret == (ssize_t)-EAGAIN && send_fails > 0) {
                        mlog(0, "sendpage of size %zu to " SC_NODEF_FMT
                             " returned EAGAIN\n", size, SC_NODEF_ARGS(sc));
                        cond_resched();
+                       --send_fails;
                        continue;
                }
                mlog(ML_ERROR, "sendpage of size %zu to " SC_NODEF_FMT

syslog:

/var/log/syslog:Jun 29 09:32:58 cvk47 kernel: [156022.769539] (kworker/u130:1,12041,9):o2net_sendpage:1026 sendpage of size 24 to node cvk61 (num 5) at 172.16.202.61:7100 returned EAGAINne

/var/log/syslog:Jun 29 09:32:58 cvk47 kernel: [156022.769542] (kworker/u130:1,12041,9):o2net_sendpage:1026 sendpage of size 24 to node cvk61 (num 5) at 172.16.202.61:7100 returned EAGAINne
/var/log/syslog:Jun 29 09:32:58 cvk47 kernel: [156022.769544] (kworker/u130:1,12041,9):o2net_sendpage:1026 sendpage of size 24 to node cvk61 (num 5) at 172.16.202.61:7100 returned EAGAINne
/var/log/syslog:Jun 29 09:32:58 cvk47 kernel: [156022.769546] (kworker/u130:1,12041,9):o2net_sendpage:1026 sendpage of

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zhangguanghui 10102
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