[etop] Show CPU utilization for last interval only

Since commit 265998a7e412cd382315632964846569c370a5a2, etop reports
the CPU (scheduler) utilization since the tool was started instead of
for the last interval only. This is now corrected.

4 files changed, 38 insertions, 25 deletions

diff --git a/lib/observer/src/etop.erl b/lib/observer/src/etop.erl
index fcb900960b..925f4456bb 100644
--- a/lib/observer/src/etop.erl
+++ b/lib/observer/src/etop.erl
@@ -23,7 +23,7 @@
 -export([start/0, start/1, config/2, stop/0, dump/1, help/0]).
 %% Internal
 -export([update/1]).
--export([loadinfo/1, meminfo/2, getopt/2]).
+-export([loadinfo/2, meminfo/2, getopt/2]).
 
 -include("etop.hrl").
 -include("etop_defs.hrl").
@@ -319,18 +319,18 @@ output(graphical) -> exit({deprecated, "Use observer instead"});
 output(text) -> etop_txt.
 
 
-loadinfo(SysI) ->
+loadinfo(SysI,Prev) ->
     #etop_info{n_procs = Procs, 
 	       run_queue = RQ, 
 	       now = Now,
 	       wall_clock = WC,
 	       runtime = RT} = SysI,
-    Cpu = calculate_cpu_utilization(WC,RT),
+    Cpu = calculate_cpu_utilization(WC,RT,Prev#etop_info.runtime),
     Clock = io_lib:format("~2.2.0w:~2.2.0w:~2.2.0w",
 			 tuple_to_list(element(2,calendar:now_to_datetime(Now)))),
     {Cpu,Procs,RQ,Clock}.
 
-calculate_cpu_utilization({_,WC},{_,RT}) ->
+calculate_cpu_utilization({_,WC},{_,RT},_) ->
     %% Old version of observer_backend, using statistics(wall_clock)
     %% and statistics(runtime)
     case {WC,RT} of
@@ -341,15 +341,23 @@ calculate_cpu_utilization({_,WC},{_,RT}) ->
 	_ ->
 	    round(100*RT/WC)
     end;
-calculate_cpu_utilization(_,undefined) ->
+calculate_cpu_utilization(_,undefined,_) ->
     %% First time collecting - no cpu utilization has been measured
     %% since scheduler_wall_time flag is not yet on
     0;
-calculate_cpu_utilization(_,RTInfo) ->
+calculate_cpu_utilization(WC,RTInfo,undefined) ->
+    %% Second time collecting - RTInfo shows scheduler_wall_time since
+    %% flag was set to true. Faking previous values by setting
+    %% everything to zero.
+    ZeroRT = [{Id,0,0} || {Id,_,_} <- RTInfo],
+    calculate_cpu_utilization(WC,RTInfo,ZeroRT);
+calculate_cpu_utilization(_,RTInfo,PrevRTInfo) ->
     %% New version of observer_backend, using statistics(scheduler_wall_time)
-    Sum = lists:foldl(fun({_,A,T},{AAcc,TAcc}) -> {A+AAcc,T+TAcc} end,
+    Sum = lists:foldl(fun({{_, A0, T0}, {_, A1, T1}},{AAcc,TAcc}) ->
+                              {(A1 - A0)+AAcc,(T1 - T0)+TAcc}
+                      end,
 		      {0,0},
-		      RTInfo),
+		      lists:zip(PrevRTInfo,RTInfo)),
     case Sum of
 	{0,0} ->
 	    0;
diff --git a/lib/observer/src/etop_txt.erl b/lib/observer/src/etop_txt.erl
index 3b4c176478..6b8f9df24f 100644
--- a/lib/observer/src/etop_txt.erl
+++ b/lib/observer/src/etop_txt.erl
@@ -22,35 +22,35 @@
 
 %%-compile(export_all).
 -export([init/1,stop/1]).
--export([do_update/3]).
+-export([do_update/4]).
 
 -include("etop.hrl").
 -include("etop_defs.hrl").
 
--import(etop,[loadinfo/1,meminfo/2]).
+-import(etop,[loadinfo/2,meminfo/2]).
 
 -define(PROCFORM,"~-15w~-20s~8w~8w~8w~8w ~-20s~n").
 
 stop(Pid) -> Pid ! stop.
 
 init(Config) ->
-    loop(Config).
+    loop(#etop_info{},Config).
 
-loop(Config) ->
-    Info = do_update(Config),
+loop(Prev,Config) ->
+    Info = do_update(Prev,Config),
     receive 
 	stop -> stopped;
-	{dump,Fd} -> do_update(Fd,Info,Config), loop(Config); 
-	{config,_,Config1} -> loop(Config1)
-    after Config#opts.intv -> loop(Config)
+	{dump,Fd} -> do_update(Fd,Info,Prev,Config), loop(Info,Config);
+	{config,_,Config1} -> loop(Info,Config1)
+    after Config#opts.intv -> loop(Info,Config)
     end.
 
-do_update(Config) ->
+do_update(Prev,Config) ->
     Info = etop:update(Config),
-    do_update(standard_io,Info,Config).
+    do_update(standard_io,Info,Prev,Config).
 
-do_update(Fd,Info,Config) ->
-    {Cpu,NProcs,RQ,Clock} = loadinfo(Info),
+do_update(Fd,Info,Prev,Config) ->
+    {Cpu,NProcs,RQ,Clock} = loadinfo(Info,Prev),
     io:nl(Fd),
     writedoubleline(Fd),
     case Info#etop_info.memi of
diff --git a/lib/observer/src/observer_pro_wx.erl b/lib/observer/src/observer_pro_wx.erl
index ee6829b847..f07b9e295a 100644
--- a/lib/observer/src/observer_pro_wx.erl
+++ b/lib/observer/src/observer_pro_wx.erl
@@ -511,7 +511,13 @@ table_holder(#holder{info=Info, attrs=Attrs,
 	    table_holder(S0);
 	{dump, Fd} ->
 	    EtopInfo = (S0#holder.etop)#etop_info{procinfo=array:to_list(Info)},
-	    etop_txt:do_update(Fd, EtopInfo, #opts{node=Node}),
+            %% The empty #etop_info{} below is a dummy previous info
+            %% value. It is used by etop to calculate the scheduler
+            %% utilization since last update. When dumping to file,
+            %% there is no previous measurement to use, so we just add
+            %% a dummy here, and the value shown will be since the
+            %% tool was started.
+	    etop_txt:do_update(Fd, EtopInfo, #etop_info{}, #opts{node=Node}),
 	    file:close(Fd),
 	    table_holder(S0);
 	stop ->
diff --git a/lib/runtime_tools/src/observer_backend.erl b/lib/runtime_tools/src/observer_backend.erl
index e943fb4a3e..b27bc63d15 100644
--- a/lib/runtime_tools/src/observer_backend.erl
+++ b/lib/runtime_tools/src/observer_backend.erl
@@ -314,13 +314,12 @@ etop_collect(Collector) ->
 
     case SchedulerWallTime of
 	undefined ->
-	    spawn(fun() -> flag_holder_proc(Collector) end),
+            erlang:system_flag(scheduler_wall_time,true),
+            spawn(fun() -> flag_holder_proc(Collector) end),
             ok;
 	_ ->
 	    ok
-    end,
-
-    erlang:system_flag(scheduler_wall_time,true).
+    end.
 
 flag_holder_proc(Collector) ->
     Ref = erlang:monitor(process,Collector),