On 04/13/2018 03:25 PM, Frediano Ziglio wrote:
Cork is a system interface implemented by Linux and some *BSD systems to
tell the system that other data are expected to be written to a socket.
This allows the system to reduce network fragmentation waiting for network
packets to be complete.
Using some replay capture and some instrumentation resulted in a
bandwith reduction of 11% and a packet reduction of 56%.
The tests was done using replay utility so results could be a bit different
from real cases as:
- replay goes as fast as it can, for instance packets could
be merged by the kernel decreasing packet numbers and a bit
byte spent (this actually make the following improves worse);
- there are fewer channels (no much cursor, sound, etc).
The following tests shows count packet and total bytes from server to
client using a real network. I used a direct cable connection using 1gb
connection and 2 laptops.
cork: 537 1582240
cork: 681 1823754
cork: 524 1583287
cork: 538 1582350
no cork: 1329 1834630
no cork: 1290 1829094
no cork: 1289 1830164
no cork: 1317 1833589
no cork: 1320 1835705
Signed-off-by: Frediano Ziglio <fziglio@xxxxxxxxxx>
---
server/red-stream.c | 40 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 39 insertions(+), 1 deletion(-)
diff --git a/server/red-stream.c b/server/red-stream.c
index 9a9c1a0f..18c4a935 100644
--- a/server/red-stream.c
+++ b/server/red-stream.c
@@ -24,6 +24,7 @@
#include <unistd.h>
#include <sys/socket.h>
#include <fcntl.h>
+#include <netinet/tcp.h>
#include <glib.h>
@@ -37,6 +38,11 @@
#include "red-stream.h"
#include "reds.h"
+// compatibility for *BSD systems
+#ifndef TCP_CORK
+#define TCP_CORK TCP_NOPUSH
+#endif
+
struct AsyncRead {
void *opaque;
uint8_t *now;
@@ -83,6 +89,8 @@ struct RedStreamPrivate {
* deallocated when main_dispatcher handles the SPICE_CHANNEL_EVENT_DISCONNECTED
* event, either from same thread or by call back from main thread. */
SpiceChannelEventInfo* info;
+ bool use_cork;
+ bool corked;
ssize_t (*read)(RedStream *s, void *buf, size_t nbyte);
ssize_t (*write)(RedStream *s, const void *buf, size_t nbyte);
@@ -92,6 +100,16 @@ struct RedStreamPrivate {
SpiceCoreInterfaceInternal *core;
};
+/**
+ * Set TCP_CORK on socket
+ */
+/* NOTE: enabled must be int */
+static int socket_set_cork(int socket, int enabled)
+{
+ SPICE_VERIFY(sizeof(enabled) == sizeof(int));
+ return setsockopt(socket, IPPROTO_TCP, TCP_CORK, &enabled, sizeof(enabled));
+}
+
static ssize_t stream_write_cb(RedStream *s, const void *buf, size_t size)
{
return write(s->socket, buf, size);
@@ -205,11 +223,31 @@ bool red_stream_write_all(RedStream *stream, const void *in_buf, size_t n)
bool red_stream_set_auto_flush(RedStream *s, bool auto_flush)
{
- return auto_flush;
+ if (s->priv->use_cork == !auto_flush) {
+ return true;
+ }
+
+ s->priv->use_cork = !auto_flush;
+ if (s->priv->use_cork) {
+ if (socket_set_cork(s->socket, 1)) {
+ s->priv->use_cork = false;
+ return false;
+ } else {
+ s->priv->corked = true;
+ }
+ } else if (s->priv->corked) {
+ socket_set_cork(s->socket, 0);
+ s->priv->corked = false;
+ }
Hi Frediano,
It would be simpler to use !auto_flash or s->priv->use_cork
and also only keep one of use_cork and corked.
Possibly the logic is a bit different and not exactly what you want.
if (socket_set_cork(s->socket, !auto_flash)) {
return false;
}
s->priv->use_cork = !auto_flash;
+ return true;
}
Uri.
void red_stream_flush(RedStream *s)
{
+ if (s->priv->corked) {
+ socket_set_cork(s->socket, 0);
+ socket_set_cork(s->socket, 1);
+ }
}
#if HAVE_SASL
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