From 2613eab11996c8d1439c2a44fbca52807be7faa6 Mon Sep 17 00:00:00 2001 From: Khazhismel Kumykov Date: Thu, 30 Apr 2020 16:48:30 -0400 Subject: dm mpath: add Historical Service Time Path Selector This new selector keeps an exponential moving average of the service time for each path (losely defined as delta between start_io and end_io), and uses this along with the number of inflight requests to estimate future service time for a path. Since we don't have a prober to account for temporally slow paths, re-try "slow" paths every once in a while (num_paths * historical_service_time). To account for fast paths transitioning to slow, if a path has not completed any request within (num_paths * historical_service_time), limit the number of outstanding requests. To account for low volume situations where number of inflight IOs would be zero, the last finish time of each path is factored in. Signed-off-by: Khazhismel Kumykov Co-developed-by: Gabriel Krisman Bertazi Signed-off-by: Gabriel Krisman Bertazi Signed-off-by: Mike Snitzer --- drivers/md/Kconfig | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'drivers/md/Kconfig') diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig index 6cb6188a61df..6665b56865b7 100644 --- a/drivers/md/Kconfig +++ b/drivers/md/Kconfig @@ -452,6 +452,17 @@ config DM_MULTIPATH_ST If unsure, say N. +config DM_MULTIPATH_HST + tristate "I/O Path Selector based on historical service time" + depends on DM_MULTIPATH + help + This path selector is a dynamic load balancer which selects + the path expected to complete the incoming I/O in the shortest + time by comparing estimated service time (based on historical + service time). + + If unsure, say N. + config DM_DELAY tristate "I/O delaying target" depends on BLK_DEV_DM -- cgit