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[PATCHv2,4/6] ui/vnc: optimize clearing in find_and_clear_dirty_height()

Message ID 1385023877-26524-5-git-send-email-pl@kamp.de
State New
Headers show

Commit Message

Peter Lieven Nov. 21, 2013, 8:51 a.m. UTC
The following artifical test (just the bitmap operation part) running
vnc_update_client 65536 times on a 2560x2048 surface illustrates the
performance difference:

All bits clean - vnc_update_client_new: 0.07 secs
                 vnc_update_client_new2: 0.07 secs
                 vnc_update_client_old: 10.98 secs

All bits dirty - vnc_update_client_new: 11.26 secs
               - vnc_update_client_new2: 0.29 secs
                 vnc_update_client_old: 20.19 secs

Few bits dirty - vnc_update_client_new: 0.07 secs
               - vnc_update_client_new2: 0.07 secs
                 vnc_update_client_old: 10.98 secs

vnc_update_client_new2 shows the performance of vnc_update_client
with this patch added.

Comparing with the test run of the last patch the performance
is at least unchanged while it is significantly improved
for the all bits dirty case.

Signed-off-by: Peter Lieven <pl@kamp.de>
---
 ui/vnc.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)
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Patch

diff --git a/ui/vnc.c b/ui/vnc.c
index 5dd1efe..3bbf2af 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -875,13 +875,10 @@  static int find_and_clear_dirty_height(struct VncState *vs,
     int h;
 
     for (h = 1; h < (height - y); h++) {
-        int tmp_x;
         if (!test_bit(last_x, vs->dirty[y + h])) {
             break;
         }
-        for (tmp_x = last_x; tmp_x < x; tmp_x++) {
-            clear_bit(tmp_x, vs->dirty[y + h]);
-        }
+        bitmap_clear(vs->dirty[y + h], last_x, x - last_x);
     }
 
     return h;