[PATCH for-8.0] nbd/server: Request TCP_NODELAY

[Eric Blake]

Nagle's algorithm adds latency in order to reduce network packet
overhead on small packets.  But when we are already using corking to
merge smaller packets into transactional requests, the extra delay
from TCP defaults just gets in the way.

For reference, qemu as an NBD client already requests TCP_NODELAY (see
nbd_connect() in nbd/client-connection.c); as does libnbd as a client
[1], and nbdkit as a server [2].

[1] 
https://gitlab.com/nbdkit/libnbd/-/blob/a48a1142/generator/states-connect.c#L39
[2] https://gitlab.com/nbdkit/nbdkit/-/blob/45b72f5b/server/sockets.c#L430

CC: Florian Westphal <fw@strlen.de>
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 nbd/server.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/nbd/server.c b/nbd/server.c
index a4750e41880..976223860bf 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -2755,6 +2755,7 @@ void nbd_client_new(QIOChannelSocket *sioc,
     }
     client->tlsauthz = g_strdup(tlsauthz);
     client->sioc = sioc;
+    qio_channel_set_delay(QIO_CHANNEL(cioc), false);
     object_ref(OBJECT(client->sioc));
     client->ioc = QIO_CHANNEL(sioc);
     object_ref(OBJECT(client->ioc));

base-commit: e3debd5e7d0ce031356024878a0a18b9d109354a
-- 
2.39.2