xbzrle: optimize XBZRLE to decrease the cache misses

[qemu.git] / docs / xbzrle.txt

diff --git a/docs/xbzrle.txt b/docs/xbzrle.txt
index cc3a26a91dd6c21bbd1a9050cf0d2aac15fb7813..52c8511a4c7f16f85ae0156beb9c4dd4f473c1bb 100644 (file)
--- a/docs/xbzrle.txt
+++ b/docs/xbzrle.txt
@@ -71,6 +71,14 @@ encoded buffer:
 encoded length 24
 e9 07 0f 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 03 01 67 01 01 69
 
+Cache update strategy
+=====================
+Keeping the hot pages in the cache is effective for decreased cache
+misses. XBZRLE uses a counter as the age of each page. The counter will
+increase after each ram dirty bitmap sync. When a cache conflict is
+detected, XBZRLE will only evict pages in the cache that are older than
+a threshold.
+
 Usage
 ======================
 1. Verify the destination QEMU version is able to decode the new format.