[Qemu-devel] [PATCH v5 09/10] migration: optimize xbzrle by reducing data copy

[<arei.gonglei@huawei.com>]

From: ChenLiang <chenliang88@huawei.com>

Reducing data copy can reduce cpu overhead.

Signed-off-by: ChenLiang <chenliang88@huawei.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
---
 arch_init.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 84a4bd3..94b62e2 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -373,11 +373,8 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t **current_data,
 
     prev_cached_page = get_cached_data(XBZRLE.cache, current_addr);
 
-    /* save current buffer into memory */
-    memcpy(XBZRLE.current_buf, *current_data, TARGET_PAGE_SIZE);
-
     /* XBZRLE encoding (if there is no overflow) */
-    encoded_len = xbzrle_encode_buffer(prev_cached_page, XBZRLE.current_buf,
+    encoded_len = xbzrle_encode_buffer(prev_cached_page, *current_data,
                                        TARGET_PAGE_SIZE, XBZRLE.encoded_buf,
                                        TARGET_PAGE_SIZE);
     if (encoded_len == 0) {
@@ -396,7 +393,8 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t **current_data,
 
     /* we need to update the data in the cache, in order to get the same data */
     if (!last_stage) {
-        memcpy(prev_cached_page, XBZRLE.current_buf, TARGET_PAGE_SIZE);
+        xbzrle_decode_buffer(XBZRLE.encoded_buf, encoded_len, prev_cached_page,
+                             TARGET_PAGE_SIZE);
     }
 
     /* Send XBZRLE based compressed page */
-- 
1.7.12.4