diff --git a/qapi/migration.json b/qapi/migration.json
index bebe9f7..744d05f 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -966,16 +966,26 @@
 # @announce-step: Increase in delay (in milliseconds) between
 #     subsequent packets in the announcement (Since 4.0)
 #
-# @compress-level: compression level
+# @compress-level: Set the compression level to be used in live
+#     migration, the compression level is an integer between 0 and 9,
+#     where 0 means no compression, 1 means the best compression
+#     speed, and 9 means best compression ratio which will consume
+#     more CPU.
 #
-# @compress-threads: compression thread count
+# @compress-threads: Set compression thread count to be used in live
+#     migration, the compression thread count is an integer between 1
+#     and 255.
 #
 # @compress-wait-thread: Controls behavior when all compression
 #     threads are currently busy.  If true (default), wait for a free
 #     compression thread to become available; otherwise, send the page
 #     uncompressed.  (Since 3.1)
 #
-# @decompress-threads: decompression thread count
+# @decompress-threads: Set decompression thread count to be used in
+#     live migration, the decompression thread count is an integer
+#     between 1 and 255. Usually, decompression is at least 4 times as
+#     fast as compression, so set the decompress-threads to the number
+#     about 1/4 of compress-threads is adequate.
 #
 # @throttle-trigger-threshold: The ratio of bytes_dirty_period and
 #     bytes_xfer_period to trigger throttling.  It is expressed as
@@ -1042,8 +1052,8 @@
 # @downtime-limit: set maximum tolerated downtime for migration.
 #     maximum downtime in milliseconds (Since 2.8)
 #
-# @x-checkpoint-delay: the delay time between two COLO checkpoints.
-#     (Since 2.8)
+# @x-checkpoint-delay: The delay time (in ms) between two COLO
+#     checkpoints in periodic mode.  (Since 2.8)
 #
 # @block-incremental: Affects how much storage is migrated when the
 #     block migration capability is enabled.  When false, the entire
@@ -1064,8 +1074,8 @@
 #     postcopy.  Defaults to 0 (unlimited).  In bytes per second.
 #     (Since 3.0)
 #
-# @max-cpu-throttle: maximum cpu throttle percentage.  The default
-#     value is 99. (Since 3.1)
+# @max-cpu-throttle: maximum cpu throttle percentage.  Defaults to 99.
+#     (Since 3.1)
 #
 # @multifd-compression: Which compression method to use.  Defaults to
 #     none.  (Since 5.0)