Merge pull request #62 from lippirk/fix-iostat-rrds

Fix accumulation of latency and avgqu_sz from iostat

src/rrdp-iostat/rrdp_iostat.ml

@@ -574,7 +574,7 @@ module Stats_value = struct
         inflight = (get_stats_read_reqs_submitted s3 ++ get_stats_write_reqs_submitted s3) -- (opt get_stats_read_reqs_completed last_s3 ++ opt get_stats_write_reqs_completed last_s3);
       }
 
-  let sumup (values : t list) : t =
+  let accumulate (values : t list) : t =
     let (++) = Int64.add in
     List.fold_left (fun acc v ->
         {
@@ -681,12 +681,12 @@ module Iostats_value = struct
         avgqu_sz = avgqu_sz /. 5.;
       }
 
-  let sumup (values : t list) : t =
-    List.fold_left (fun acc v ->
-        {
-          latency = acc.latency +. v.latency;
-          avgqu_sz = acc.avgqu_sz +. v.avgqu_sz;
-        }) empty values
+  let accumulate (values : t list) : t =
+    let max acc v = { latency = Float.max acc.latency v.latency
+                    ; avgqu_sz = Float.max acc.avgqu_sz v.avgqu_sz
+                    }
+    in
+    List.fold_left max empty values
 
   let [@warning "-27"] make_ds  ~owner ~name ~key_format (value : t) =
     let ds_make = Ds.ds_make ~default:true in
@@ -761,15 +761,15 @@ let gen_metrics () =
       ) sr_vdi_to_stats in
 
   (* sum up to SR level stats values *)
-  let get_sr_to_stats_values ~stats_values ~sum_fun =
+  let get_sr_to_stats_values ~stats_values ~accumulate =
     let sr_to_stats_values = sr_to_sth stats_values in
     List.map (fun (sr, stats_values) ->
-        (sr, sum_fun stats_values)
+        (sr, accumulate stats_values)
       ) sr_to_stats_values
   in
 
-  let sr_to_iostats_values = get_sr_to_stats_values ~stats_values:sr_vdi_to_iostats_values ~sum_fun:Iostats_value.sumup in
-  let sr_to_stats_values   = get_sr_to_stats_values ~stats_values:sr_vdi_to_stats_values   ~sum_fun:Stats_value.sumup   in
+  let sr_to_iostats_values = get_sr_to_stats_values ~stats_values:sr_vdi_to_iostats_values ~accumulate:Iostats_value.accumulate in
+  let sr_to_stats_values   = get_sr_to_stats_values ~stats_values:sr_vdi_to_stats_values   ~accumulate:Stats_value.accumulate in
 
   (* create SR level data sources *)
   let data_sources_iostats = List.map (