hbal: Add a new min-score option

This new parameter causes the algorithm to finish (or even not start at
all) if we reach/have a score better than it.

diff --git a/Ganeti/HTools/Cluster.hs b/Ganeti/HTools/Cluster.hs
index 2474fa4..966362d 100644 (file)
--- a/Ganeti/HTools/Cluster.hs
+++ b/Ganeti/HTools/Cluster.hs
@@ -15,6 +15,7 @@ module Ganeti.HTools.Cluster
     , Solution(..)
     , Table(..)
     , Removal
+    , Score
     -- * Generic functions
     , totalResources
     -- * First phase functions

diff --git a/hbal.1 b/hbal.1
index 767b4ef..da58ebe 100644 (file)
--- a/hbal.1
+++ b/hbal.1
@@ -9,6 +9,7 @@ hbal \- Cluster balancer for Ganeti
 .B "[-o]"
 .BI "[-l" limit "]"
 .BI "[-O" name... "]"
+.BI "[-e" score "]"
 .BI "[-m " cluster "]"
 .BI "[-n " nodes-file " ]"
 .BI "[-i " instances-file "]"
@@ -248,6 +249,25 @@ the percentage of instances on offline nodes)
 .RE
 
 .TP
+.BI "-e" score ", --min-score=" score
+This parameter denotes the minimum score we are happy with and alters
+the computation in two ways:
+.RS
+.RS 4
+.TP 3
+\(em
+if the cluster has the initial score lower than this value, then we
+don't enter the algorithm at all, and exit with success
+.TP
+\(em
+during the iterative process, if we reach a score lower than this
+value, we exit the algorithm
+.RE
+The default value of the parameter is currently \fI1e-9\fR (chosen
+empirically).
+.RE
+
+.TP
 .BI "-n" nodefile ", --nodes=" nodefile
 The name of the file holding node information (if not collecting via
 RAPI), instead of the default \fInodes\fR file (but see below how to

diff --git a/hbal.hs b/hbal.hs
index bcd517a..b6c2d16 100644 (file)
--- a/hbal.hs
+++ b/hbal.hs
@@ -35,6 +35,7 @@ data Options = Options
     , optMaster    :: String         -- ^ Collect data from RAPI
     , optVerbose   :: Int            -- ^ Verbosity level
     , optOffline   :: [String]       -- ^ Names of offline nodes
+    , optMinScore  :: Cluster.Score  -- ^ The minimum score we aim for
     , optShowVer   :: Bool           -- ^ Just show the program version
     , optShowHelp  :: Bool           -- ^ Just show the help
     } deriving Show
@@ -53,6 +54,7 @@ defaultOptions  = Options
  , optMaster    = ""
  , optVerbose   = 0
  , optOffline   = []
+ , optMinScore  = 1e-9
  , optShowVer   = False
  , optShowHelp  = False
  }
@@ -90,7 +92,10 @@ options =
       "increase the verbosity level"
     , Option ['O']     ["offline"]
       (ReqArg (\ n opts -> opts { optOffline = n:optOffline opts }) "NODE")
-       " set node as offline"
+      " set node as offline"
+    , Option ['e']     ["min-score"]
+      (ReqArg (\ e opts -> opts { optMinScore = read e }) "EPSILON")
+      " mininum score to aim for"
     , Option ['V']     ["version"]
       (NoArg (\ opts -> opts { optShowVer = True}))
       "show the version of the program"
@@ -111,9 +116,11 @@ iterateDepth :: Cluster.Table    -- ^ The starting table
              -> Int              -- ^ Max instance name len
              -> [[String]]       -- ^ Current command list
              -> Bool             -- ^ Wheter to be silent
+             -> Cluster.Score    -- ^ Score at which to stop
              -> IO (Cluster.Table, [[String]]) -- ^ The resulting table and
                                                -- commands
-iterateDepth ini_tbl max_rounds ktn kti nmlen imlen cmd_strs oneline =
+iterateDepth ini_tbl max_rounds ktn kti nmlen imlen
+             cmd_strs oneline min_score =
     let Cluster.Table ini_nl ini_il ini_cv ini_plc = ini_tbl
         all_inst = Container.elems ini_il
         node_idx = map Node.idx . filter (not . Node.offline) $
@@ -133,9 +140,9 @@ iterateDepth ini_tbl max_rounds ktn kti nmlen imlen cmd_strs oneline =
           putStrLn sol_line
           hFlush stdout
         (if fin_cv < ini_cv then -- this round made success, try deeper
-             if allowed_next
+             if allowed_next && fin_cv > min_score
              then iterateDepth fin_tbl max_rounds ktn kti
-                  nmlen imlen upd_cmd_strs oneline
+                  nmlen imlen upd_cmd_strs oneline min_score
              -- don't go deeper, but return the better solution
              else return (fin_tbl, upd_cmd_strs)
          else
@@ -215,6 +222,17 @@ main = do
 
   let ini_cv = Cluster.compCV nl
       ini_tbl = Cluster.Table nl il ini_cv []
+      min_cv = optMinScore opts
+
+  when (ini_cv < min_cv) $ do
+         (if oneline then
+              printf "%.8f %d %.8f %8.3f\n"
+                     ini_cv (0::Integer) ini_cv (1::Double)
+          else printf "Cluster is already well balanced (initial score %.6g,\n\
+                      \minimum score %.6g).\nNothing to do, exiting\n"
+                      ini_cv min_cv)
+         exitWith ExitSuccess
+
   unless oneline (if verbose > 1 then
                       printf "Initial coefficients: overall %.8f, %s\n"
                       ini_cv (Cluster.printStats nl)
@@ -227,7 +245,7 @@ main = do
       nmlen = mlen_fn ktn
 
   (fin_tbl, cmd_strs) <- iterateDepth ini_tbl (optMaxLength opts)
-                         ktn kti nmlen imlen [] oneline
+                         ktn kti nmlen imlen [] oneline min_cv
   let (Cluster.Table fin_nl _ fin_cv fin_plc) = fin_tbl
       ord_plc = reverse fin_plc
       sol_msg = if null fin_plc