[Qemu-devel] [PATCH] vnc: return directly if no vnc client connected

[Qemu-devel] [PATCH] vnc: return directly if no vnc client connected

[arei.gonglei]

From: ChenLiang <chenliang88@huawei.com>

graphic_hw_update and vnc_refresh_server_surface aren't
need to do when no vnc client connected. It can reduce
lock contention, because vnc_refresh will hold global big
lock two millisecond every three seconds.

Signed-off-by: ChenLiang <chenliang88@huawei.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
---
 ui/vnc.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/ui/vnc.c b/ui/vnc.c
index 0fe6eff..092ba2e 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -2768,6 +2768,11 @@ static void vnc_refresh(DisplayChangeListener *dcl)
     VncState *vs, *vn;
     int has_dirty, rects = 0;
 
+    if (QTAILQ_EMPTY(&vd->clients)) {
+        update_displaychangelistener(&vd->dcl, VNC_REFRESH_INTERVAL_MAX);
+        return;
+    }
+
     graphic_hw_update(NULL);
 
     if (vnc_trylock_display(vd)) {
@@ -2783,11 +2788,6 @@ static void vnc_refresh(DisplayChangeListener *dcl)
         /* vs might be free()ed here */
     }
 
-    if (QTAILQ_EMPTY(&vd->clients)) {
-        update_displaychangelistener(&vd->dcl, VNC_REFRESH_INTERVAL_MAX);
-        return;
-    }
-
     if (has_dirty && rects) {
         vd->dcl.update_interval /= 2;
         if (vd->dcl.update_interval < VNC_REFRESH_INTERVAL_BASE) {
-- 
1.7.12.4

Re: [Qemu-devel] [PATCH] vnc: return directly if no vnc client connected

[Gerd Hoffmann]

On Mo, 2014-09-29 at 15:00 +0800, arei.gonglei@huawei.com wrote:
> graphic_hw_update and vnc_refresh_server_surface aren't
> need to do when no vnc client connected. It can reduce
> lock contention, because vnc_refresh will hold global big
> lock two millisecond every three seconds.

Added to vnc patch queue.

thanks,
  Gerd