diff --git a/qemu/tests/balloon_check.py b/qemu/tests/balloon_check.py
index 70fb28467c077ab0d63f13ed2ca2bd8d868d4712..d6cf2444be2ef7fbec08e3b913f88e3b99841089 100644
--- a/qemu/tests/balloon_check.py
+++ b/qemu/tests/balloon_check.py
@@ -20,7 +20,6 @@ class BallooningTest(MemoryBaseTest):
 
     def __init__(self, test, params, env):
         self.test_round = 0
-        self.ratio = float(params.get("ratio", 0.1))
         super(BallooningTest, self).__init__(test, params, env)
 
         self.vm = env.get_vm(params["main_vm"])
@@ -183,19 +182,20 @@ class BallooningTest(MemoryBaseTest):
         max_size = self.ori_mem
         min_size = self.params.get("minmem", "512M")
         min_size = int(float(utils_misc.normalize_data_size(min_size)))
+        balloon_buffer = self.params.get("balloon_buffer", 300)
         if self.params.get('os_type') == 'windows':
             logging.info("Get windows miminum balloon value:")
             self.vm.balloon(1)
             balloon_timeout = self.params.get("balloon_timeout", 900)
             self.wait_for_balloon_complete(balloon_timeout)
-            used_size = int(self.get_ballooned_memory() + self.ratio * self.ori_mem)
+            used_size = min((self.get_ballooned_memory() + balloon_buffer), max_size)
             self.vm.balloon(max_size)
             self.wait_for_balloon_complete(balloon_timeout)
             self.ori_gmem = self.get_memory_status()
         else:
             vm_total = self.get_memory_status()
             vm_mem_free = self.get_free_mem()
-            used_size = vm_total - vm_mem_free + 16
+            used_size = min((self.ori_mem - vm_mem_free + balloon_buffer), max_size)
         if balloon_type == "enlarge":
             min_size = self.current_mmem
         elif balloon_type == "evict":
diff --git a/qemu/tests/cfg/balloon_check.cfg b/qemu/tests/cfg/balloon_check.cfg
index 55e719c03f469526be7c25ee3ef061323f09aa13..2154c12aaaf7c90246360268c177374a9c5e03b3 100644
--- a/qemu/tests/cfg/balloon_check.cfg
+++ b/qemu/tests/cfg/balloon_check.cfg
@@ -7,10 +7,6 @@
     balloon_dev_add_bus = yes
     iterations = 5
     free_mem_cmd = cat /proc/meminfo |grep MemFree
-    Linux:
-        ratio = 1
-    Windows:
-        ratio = 0.5
     variants:
         - balloon_base:
 
diff --git a/qemu/tests/cfg/balloon_hotplug.cfg b/qemu/tests/cfg/balloon_hotplug.cfg
index 1dfce90e03fa2f72fd4aa2e4bce8f72a668c5d2f..89b6eb779a4560e2951a009c5f7f84ea5156c72f 100644
--- a/qemu/tests/cfg/balloon_hotplug.cfg
+++ b/qemu/tests/cfg/balloon_hotplug.cfg
@@ -8,10 +8,6 @@
     free_mem_cmd = cat /proc/meminfo |grep MemFree
     reboot_method = shell
     shutdown_method = shell
-    Linux:
-        ratio = 1
-    Windows:
-        ratio = 0.5
     run_sub_test_after_balloon = no
     test_tags = "evict enlarge"
     balloon_type_evict = evict
diff --git a/qemu/tests/cfg/balloon_illegal.cfg b/qemu/tests/cfg/balloon_illegal.cfg
index 5b6199736ace81323877bb09a7e5cdf6965e1768..b6335078e55aed2d1ad2db10d43501c14dbf4c07 100644
--- a/qemu/tests/cfg/balloon_illegal.cfg
+++ b/qemu/tests/cfg/balloon_illegal.cfg
@@ -6,10 +6,6 @@
     balloon_dev_devid = balloon0
     balloon_dev_add_bus = yes
     free_mem_cmd = cat /proc/meminfo | grep MemFree
-    Linux:
-        ratio = 1
-    Windows:
-        ratio = 0.5
     illegal_value_check = yes
     test_tags = "evict enlarge"
     balloon_type_evict = evict
diff --git a/qemu/tests/cfg/balloon_in_use.cfg b/qemu/tests/cfg/balloon_in_use.cfg
index d15b0e727b5ec2d4ef9e1aa28d4357a122c14739..84789d8b2145c64648f706fc6f488297b8a00cff 100644
--- a/qemu/tests/cfg/balloon_in_use.cfg
+++ b/qemu/tests/cfg/balloon_in_use.cfg
@@ -5,7 +5,6 @@
     balloon_dev_devid = balloon0
     balloon_dev_add_bus = yes
     repeat_times = 5
-    ratio = 0.5
     wait_bg_time = 720
     time_for_video = 600
     start_vm = yes
diff --git a/qemu/tests/cfg/balloon_service.cfg b/qemu/tests/cfg/balloon_service.cfg
index ed3a3a6f23f03485f392da477285423444fb2f50..b51433911ea1e6a3637e45ea1a61e17fb614fc4c 100644
--- a/qemu/tests/cfg/balloon_service.cfg
+++ b/qemu/tests/cfg/balloon_service.cfg
@@ -25,7 +25,6 @@
     set_balloon_property = "guest-stats-polling-interval"
     get_balloon_property = "guest-stats"
     polling_sleep_time = 20
-    ratio = 0.1
     run_sub_test_after_balloon = no
     test_tags = "evict enlarge"
     balloon_type_evict = evict
diff --git a/qemu/tests/cfg/balloon_stress.cfg b/qemu/tests/cfg/balloon_stress.cfg
index 2533e3239a6dc7b493458ec04a2f42e7dfa40b43..ffa53d260d3659e03049ddd049654b146efc5e5f 100644
--- a/qemu/tests/cfg/balloon_stress.cfg
+++ b/qemu/tests/cfg/balloon_stress.cfg
@@ -24,7 +24,6 @@
         play_video_cmd = '"%s" "%s" /play /fullscreen'
         time_for_video = 1200
         guest_alias = "Win2008-sp2-32:2k8\x86,Win2008-sp2-64:2k8\amd64,Win2008-r2-64:2k8\amd64,Win2012-64:2k12\amd64,Win2012-64r2:2k12\amd64"
-        ratio = 0.5
     Linux:
         # Use a low stress to make sure guest can response during stress
         stress_args = "--cpu 4 --io 4 --vm 2 --vm-bytes 256M"
diff --git a/qemu/tests/cfg/win_virtio_driver_update_test.cfg b/qemu/tests/cfg/win_virtio_driver_update_test.cfg
index 20e9e1192c6976f074874c7ad9b4072c963be7fd..db589614ff5c893a8874da90fa92c37c9580ee0a 100644
--- a/qemu/tests/cfg/win_virtio_driver_update_test.cfg
+++ b/qemu/tests/cfg/win_virtio_driver_update_test.cfg
@@ -43,7 +43,6 @@
             run_bgstress = balloon_check
             virtio_balloon_pause = 10.0
             free_mem_cmd = cat /proc/meminfo |grep MemFree
-            ratio = 0.5
             run_sub_test_after_balloon = no
             test_tags = "evict enlarge"
             balloon_type_evict = evict