From aaaa0e43511bb0f2e2d1b4791efa0e7e48b7bbbc Mon Sep 17 00:00:00 2001
From: Iustin Pop <iustin@google.com>
Date: Sat, 14 Feb 2009 22:22:26 +0100
Subject: [PATCH] Change the balancing algorithm
This patch changes the balancing algorithm to not iterate linearly over
the instances (in a random, but fixed order), instead selecting at each
step the best next move. This should allow a better score (most of the
time), and usually also a shorter solution.
---
src/Cluster.hs | 60 +++++++++++++++++++++++++++++++-------------------
1 file changed, 37 insertions(+), 23 deletions(-)
diff --git a/src/Cluster.hs b/src/Cluster.hs
index c45f9b93c..1ba22c55d 100644
--- a/src/Cluster.hs
+++ b/src/Cluster.hs
@@ -394,29 +394,43 @@ checkMove :: Table -- ^ The current solution
-> [Instance.Instance] -- ^ List of instances still to move
-> Table -- ^ The new solution
checkMove ini_tbl victims =
- let target = head victims
- opdx = Instance.pnode target
- osdx = Instance.snode target
- vtail = tail victims
- have_tail = (length vtail) > 0
- Table ini_nl _ _ _ = ini_tbl
- nodes = filter (\node -> let idx = Node.idx node
- in idx /= opdx && idx /= osdx)
- $ Container.elems ini_nl
- aft_failover = checkSingleStep ini_tbl target ini_tbl Failover
- next_tbl =
- foldl'
- (\ accu_p new_node ->
- let
- new_idx = Node.idx new_node
- pmoves = [ReplacePrimary new_idx,
- ReplaceSecondary new_idx]
- in
- foldl' (checkSingleStep ini_tbl target) accu_p pmoves
- ) aft_failover nodes
- in if have_tail then checkMove next_tbl vtail
- else next_tbl
-
+ let Table ini_nl _ _ ini_plc = ini_tbl
+ best_tbl =
+ foldl -- iterate over all instances, computing the best move
+ (\ step_tbl target ->
+ let
+ opdx = Instance.pnode target
+ osdx = Instance.snode target
+ nodes = filter (\node -> let idx = Node.idx node
+ in idx /= opdx && idx /= osdx)
+ $ Container.elems ini_nl
+ aft_failover = checkSingleStep ini_tbl
+ target ini_tbl Failover
+ next_tbl = -- iterate over the possible nodes for
+ -- this instance
+ foldl'
+ (\ accu_p new_node ->
+ let
+ new_idx = Node.idx new_node
+ pmoves = [ReplacePrimary new_idx,
+ ReplaceSecondary new_idx]
+ in
+ foldl' -- while doing both possible moves
+ (checkSingleStep ini_tbl target) accu_p pmoves
+ ) aft_failover nodes
+ in
+ compareTables step_tbl next_tbl
+ ) ini_tbl victims
+ in let
+ Table _ _ _ best_plc = best_tbl
+ (target, _, _) = head best_plc
+ vtail = filter (\inst -> Instance.idx inst /= target) victims
+ in
+ if length best_plc == length ini_plc then -- no advancement
+ ini_tbl
+ else
+ if null vtail then best_tbl
+ else checkMove best_tbl vtail
{- | Auxiliary function for solution computation.
--
GitLab