[Qemu-devel] [PATCH v2 2/2] xbzrle: check 8 bytes at a time after an concurrency scene

[<arei.gonglei@huawei.com>]

From: ChenLiang <chenliang88@huawei.com>

The logic of old code is correct. But Checking byte by byte will
consume time after an concurrency scene.

Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: ChenLiang <chenliang88@huawei.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
---
 xbzrle.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/xbzrle.c b/xbzrle.c
index bf08c56..f2824db 100644
--- a/xbzrle.c
+++ b/xbzrle.c
@@ -50,16 +50,24 @@ int xbzrle_encode_buffer(uint8_t *old_buf, uint8_t *new_buf, int slen,
 
         /* word at a time for speed */
         if (!res) {
-            while (i < slen &&
-                   (*(long *)(old_buf + i)) == (*(long *)(new_buf + i))) {
-                i += sizeof(long);
-                zrun_len += sizeof(long);
-            }
-
-            /* go over the rest */
-            while (i < slen && old_buf[i] == new_buf[i]) {
-                zrun_len++;
-                i++;
+            while (i < slen) {
+                if ((*(long *)(old_buf + i)) == (*(long *)(new_buf + i))) {
+                    i += sizeof(long);
+                    zrun_len += sizeof(long);
+                } else {
+                    /* go over the rest */
+                    for (j = 0; j < sizeof(long); j++) {
+                        if (old_buf[i] == new_buf[i]) {
+                            i++;
+                            zrun_len++;
+                        } else {
+                            break;
+                        }
+                    }
+                    if (j != sizeof(long)) {
+                        break;
+                    }
+                }
             }
         }
 
-- 
1.7.12.4