commit c522d0e2dee3774884a731691a702126901a1a88
author aliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162> Fri Mar 20 15:59:24 2009 +0000
committer aliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162> Fri Mar 20 15:59:24 2009 +0000
tree 3a214688f7148c604774d5f04f8ec985c7b61d1f
parent 23decc87cc5e52eb3021cf05b64347b884698b17

vnc: throttle screen updates. (Gerd Hoffmann)

This patch makes the vnc server code skip screen refreshes in case
there is data in the output buffer.  This reduces the refresh rate to
throttle the bandwidth needed in case the network link is saturated.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6862 c046a42c-6fe2-441c-8c8c-71466251a162

vnc.c

diff --git a/vnc.c b/vnc.c
index de9edea..6d93215 100644
--- a/vnc.c
+++ b/vnc.c
@@ -657,6 +657,7 @@
 
 static void vnc_copy(VncState *vs, int src_x, int src_y, int dst_x, int dst_y, int w, int h)
 {
+    vs->force_update = 1;
     vnc_update_client(vs);
 
     vnc_write_u8(vs, 0);  /* msg id */
@@ -710,6 +711,12 @@
         int saved_offset;
         int has_dirty = 0;
 
+        if (vs->output.offset && !vs->audio_cap && !vs->force_update) {
+            /* kernel send buffers are full -> drop frames to throttle */
+            qemu_mod_timer(vs->timer, qemu_get_clock(rt_clock) + VNC_REFRESH_INTERVAL);
+            return;
+        }
+
         vga_hw_update();
 
         /*
@@ -745,7 +752,7 @@
             server_row += ds_get_linesize(vs->ds);
         }
 
-        if (!has_dirty && !vs->audio_cap) {
+        if (!has_dirty && !vs->audio_cap && !vs->force_update) {
             qemu_mod_timer(vs->timer, qemu_get_clock(rt_clock) + VNC_REFRESH_INTERVAL);
             return;
         }
@@ -789,6 +796,7 @@
         vs->output.buffer[saved_offset] = (n_rectangles >> 8) & 0xFF;
         vs->output.buffer[saved_offset + 1] = n_rectangles & 0xFF;
         vnc_flush(vs);
+        vs->force_update = 0;
 
     }
 
@@ -1407,6 +1415,7 @@
 
     int i;
     vs->need_update = 1;
+    vs->force_update = 1;
     if (!incremental) {
         for (i = 0; i < h; i++) {
             vnc_set_bits(vs->guest.dirty[y_position + i],

vnc.h

diff --git a/vnc.h b/vnc.h
index ce9aa49..3ae95f3 100644
--- a/vnc.h
+++ b/vnc.h
@@ -121,6 +121,7 @@
 
     VncDisplay *vd;
     int need_update;
+    int force_update;
     uint32_t features;
     int absolute;
     int last_x;