[dm-devel] [PATCH v2 17/20] libmultipath: path latency: fix default base num
Martin Wilck
mwilck at suse.com
Sat Jan 13 21:19:35 UTC 2018
I don't think anyone can measure latency to 1% accuracy. It's
better to not even pretend to be able to. 10% should be fine
even for the most latency-critical environments.
---
libmultipath/prioritizers/path_latency.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/libmultipath/prioritizers/path_latency.c b/libmultipath/prioritizers/path_latency.c
index 9d5397ec1b3a..b8c5bc7c50a4 100644
--- a/libmultipath/prioritizers/path_latency.c
+++ b/libmultipath/prioritizers/path_latency.c
@@ -42,8 +42,9 @@
#define DEF_IO_NUM 100
#define MAX_BASE_NUM 10
-#define MIN_BASE_NUM 1.01
-#define DEF_BASE_NUM 1.5
+#define MIN_BASE_NUM 1.1
+// This is 10**(1/4). 4 prio steps correspond to a factor of 10.
+#define DEF_BASE_NUM 1.77827941004
#define MAX_AVG_LATENCY 100000000. /* Unit: us */
#define MIN_AVG_LATENCY 1. /* Unit: us */
--
2.15.1
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