Merge branch 'rickard/timer-optimization/OTP-12650'

* rickard/timer-optimization/OTP-12650:
  Timer fixes, documentation, and test cases

Conflicts:
	erts/emulator/beam/erl_hl_timer.c

3 files changed, 343 insertions, 63 deletions

diff --git a/erts/emulator/test/after_SUITE.erl b/erts/emulator/test/after_SUITE.erl
index 699a1436ce..c855481489 100644
--- a/erts/emulator/test/after_SUITE.erl
+++ b/erts/emulator/test/after_SUITE.erl
@@ -27,7 +27,8 @@
 	 init_per_group/2,end_per_group/2, 
 	 t_after/1, receive_after/1, receive_after_big/1,
 	 receive_after_errors/1, receive_var_zero/1, receive_zero/1,
-	 multi_timeout/1, receive_after_32bit/1]).
+	 multi_timeout/1, receive_after_32bit/1,
+	 receive_after_blast/1]).
 
 -export([init_per_testcase/2, end_per_testcase/2]).
 
@@ -40,7 +41,7 @@ suite() -> [{ct_hooks,[ts_install_cth]}].
 all() -> 
     [t_after, receive_after, receive_after_big,
      receive_after_errors, receive_var_zero, receive_zero,
-     multi_timeout, receive_after_32bit].
+     multi_timeout, receive_after_32bit, receive_after_blast].
 
 groups() -> 
     [].
@@ -244,4 +245,26 @@ recv_after_32bit(I, T) when I rem 2 =:= 0 ->
     receive after T -> exit(timeout) end;
 recv_after_32bit(_, _) ->
     receive after 16#ffffFFFF -> exit(timeout) end.
-		    
+
+blaster() ->
+    receive
+	{go, TimeoutTime} ->
+	    Tmo = TimeoutTime - erlang:monotonic_time(milli_seconds),
+	    receive after Tmo -> ok end
+    end.
+
+spawn_blasters(0) ->
+    [];
+spawn_blasters(N) ->
+    [spawn_monitor(fun () -> blaster() end)|spawn_blasters(N-1)].
+
+receive_after_blast(Config) when is_list(Config) ->
+    PMs = spawn_blasters(10000),
+    TimeoutTime = erlang:monotonic_time(milli_seconds) + 5000,
+    lists:foreach(fun ({P, _}) -> P ! {go, TimeoutTime} end, PMs),
+    lists:foreach(fun ({P, M}) ->
+			  receive
+			      {'DOWN', M, process, P, normal} ->
+				  ok
+			  end
+		  end, PMs).
diff --git a/erts/emulator/test/system_info_SUITE.erl b/erts/emulator/test/system_info_SUITE.erl
index 0fd6696536..e3ac2d5d83 100644
--- a/erts/emulator/test/system_info_SUITE.erl
+++ b/erts/emulator/test/system_info_SUITE.erl
@@ -264,6 +264,37 @@ memory_test(_Config) ->
 		     []),
     cmp_memory(MWs, "unlink procs"),
 
+    mem_workers_call(MWs, 
+		     fun () ->
+			     lists:foreach(
+			       fun (P) ->
+				       Tmr = erlang:start_timer(1 bsl 34,
+								P,
+								hello),
+				       Tmrs = case get('BIF_TMRS') of
+						  undefined -> [];
+						  Rs -> Rs
+					      end,
+				       true = is_reference(Tmr),
+				       put('BIF_TMRS', [Tmr|Tmrs])
+			       end, Ps)
+		     end,
+		     []),
+    cmp_memory(MWs, "start BIF timer procs"),
+
+    mem_workers_call(MWs, 
+		     fun () ->
+			     lists:foreach(fun (Tmr) ->
+						   true = is_reference(Tmr),
+						   true = is_integer(erlang:cancel_timer(Tmr))
+					   end, get('BIF_TMRS')),
+			     put('BIF_TMRS', undefined),
+			     garbage_collect()
+		     end,
+		     []),
+    erts_debug:set_internal_state(wait, deallocations),
+    cmp_memory(MWs, "cancel BIF timer procs"),
+
     DMs = mem_workers_call(MWs,
 			   fun () ->
 				   lists:map(fun (P) ->
diff --git a/erts/emulator/test/timer_bif_SUITE.erl b/erts/emulator/test/timer_bif_SUITE.erl
index 3701dd8437..d406456f98 100644
--- a/erts/emulator/test/timer_bif_SUITE.erl
+++ b/erts/emulator/test/timer_bif_SUITE.erl
@@ -26,11 +26,17 @@
 	 cancel_timer_1/1,
 	 start_timer_big/1, send_after_big/1,
 	 start_timer_e/1, send_after_e/1, cancel_timer_e/1,
-	 read_timer_trivial/1, read_timer/1,
-	 cleanup/1, evil_timers/1, registered_process/1]).
+	 read_timer_trivial/1, read_timer/1, read_timer_async/1,
+	 cleanup/1, evil_timers/1, registered_process/1, same_time_yielding/1,
+	 same_time_yielding_with_cancel/1, same_time_yielding_with_cancel_other/1,
+	 same_time_yielding_with_cancel_other_accessor/1, auto_cancel_yielding/1]).
 
 -include_lib("test_server/include/test_server.hrl").
 
+-define(SHORT_TIMEOUT, 5000). %% Bif timers as short as this may be pre-allocated
+-define(TIMEOUT_YIELD_LIMIT, 100).
+-define(AUTO_CANCEL_YIELD_LIMIT, 100).
+
 init_per_testcase(_Case, Config) ->
     ?line Dog=test_server:timetrap(test_server:seconds(30)),
     case catch erts_debug:get_internal_state(available_internal_state) of
@@ -45,6 +51,7 @@ end_per_testcase(_Case, Config) ->
     ok.
 
 init_per_suite(Config) ->
+    erts_debug:set_internal_state(available_internal_state, true),
     Config.
 
 end_per_suite(_Config) ->
@@ -56,8 +63,12 @@ all() ->
     [start_timer_1, send_after_1, send_after_2,
      cancel_timer_1, start_timer_e, send_after_e,
      cancel_timer_e, start_timer_big, send_after_big,
-     read_timer_trivial, read_timer, cleanup, evil_timers,
-     registered_process].
+     read_timer_trivial, read_timer, read_timer_async,
+     cleanup, evil_timers, registered_process,
+     same_time_yielding, same_time_yielding_with_cancel,
+     same_time_yielding_with_cancel_other,
+     same_time_yielding_with_cancel_other_accessor,
+     auto_cancel_yielding].
 
 groups() -> 
     [].
@@ -162,7 +173,7 @@ cancel_timer_1(Config) when is_list(Config) ->
 start_timer_e(doc) -> ["Error cases for start_timer/3"];
 start_timer_e(Config) when is_list(Config) ->
     ?line {'EXIT', _} = (catch erlang:start_timer(-4, self(), hej)),
-    ?line {'EXIT', _} = (catch erlang:start_timer(4728472847827482,
+    ?line {'EXIT', _} = (catch erlang:start_timer(1 bsl 64,
 						  self(), hej)),
 
     ?line {'EXIT', _} = (catch erlang:start_timer(4.5, self(), hej)),
@@ -180,7 +191,7 @@ send_after_e(doc) -> ["Error cases for send_after/3"];
 send_after_e(suite) -> [];
 send_after_e(Config) when is_list(Config) ->
     ?line {'EXIT', _} = (catch erlang:send_after(-4, self(), hej)),
-    ?line {'EXIT', _} = (catch erlang:send_after(4728472847827482,
+    ?line {'EXIT', _} = (catch erlang:send_after(1 bsl 64,
 						 self(), hej)),
 
     ?line {'EXIT', _} = (catch erlang:send_after(4.5, self(), hej)),
@@ -213,44 +224,79 @@ read_timer_trivial(Config) when is_list(Config) ->
 read_timer(doc) -> ["Test that read_timer/1 seems to return the correct values."];
 read_timer(suite) -> [];
 read_timer(Config) when is_list(Config) ->
-    ?line Big = 1 bsl 31,
-    ?line R = erlang:send_after(Big, self(), hej_hopp),
+    process_flag(scheduler, 1),
+    Big = 1 bsl 31,
+    R = erlang:send_after(Big, self(), hej_hopp),
+
+    receive after 200 -> ok end,		% Delay and clear reductions.
+    Left = erlang:read_timer(R),
+    Left2 = erlang:cancel_timer(R),
+    case Left == Left2 of
+	true -> ok;
+	false -> Left = Left2 + 1
+    end,
+    false = erlang:read_timer(R),
 
-    ?line receive after 200 -> ok end,		% Delay and clear reductions.
-    ?line Left = erlang:read_timer(R),
-    ?line Left = erlang:cancel_timer(R),
-    ?line false = erlang:read_timer(R),
+    case Big - Left of
+	Diff when Diff >= 200, Diff < 10000 ->
+	    ok;
+	_Diff ->
+	    test_server:fail({big, Big, Left})
+    end,
+    process_flag(scheduler, 0),
+    ok.
 
-    ?line case Big - Left of
-	      Diff when Diff >= 200, Diff < 10000 ->
-		  ok;
-	      _Diff ->
-		  test_server:fail({big, Big, Left})
-	  end,
+read_timer_async(doc) -> ["Test that read_timer/1 seems to return the correct values."];
+read_timer_async(suite) -> [];
+read_timer_async(Config) when is_list(Config) ->
+    process_flag(scheduler, 1),
+    Big = 1 bsl 33,
+    R = erlang:send_after(Big, self(), hej_hopp),
+
+    %% Access from another scheduler
+    process_flag(scheduler, erlang:system_info(schedulers_online)),
+
+    receive after 200 -> ok end,		% Delay and clear reductions.
+    ok = erlang:read_timer(R, [{async, true}]),
+    ok = erlang:cancel_timer(R, [{async, true}, {info, true}]),
+    ok = erlang:read_timer(R, [{async, true}]),
+
+    {read_timer, R, Left} = receive_one(),
+    {cancel_timer, R, Left2} = receive_one(),
+    case Left == Left2 of
+	true -> ok;
+	false -> Left = Left2 + 1
+    end,
+    {read_timer, R, false} = receive_one(),
+
+    case Big - Left of
+	Diff when Diff >= 200, Diff < 10000 ->
+	    ok;
+	_Diff ->
+	    test_server:fail({big, Big, Left})
+    end,
+    process_flag(scheduler, 0),
     ok.
 
 cleanup(doc) -> [];
 cleanup(suite) -> [];
 cleanup(Config) when is_list(Config) ->
-    {skipped, "Test needs to be UPDATED for new timer implementation"}.
-
-cleanup_test(Config) when is_list(Config) ->
     ?line Mem = mem(),
     %% Timer on dead process
     ?line P1 = spawn(fun () -> ok end),
     ?line wait_until(fun () -> process_is_cleaned_up(P1) end),
-    ?line T1 = erlang:start_timer(10000, P1, "hej"),
-    ?line T2 = erlang:send_after(10000, P1, "hej"),
+    ?line T1 = erlang:start_timer(?SHORT_TIMEOUT*2, P1, "hej"),
+    ?line T2 = erlang:send_after(?SHORT_TIMEOUT*2, P1, "hej"),
     receive after 1000 -> ok end,
     ?line Mem = mem(),
     ?line false = erlang:read_timer(T1),
     ?line false = erlang:read_timer(T2),
     ?line Mem = mem(),
     %% Process dies before timeout
-    ?line P2 = spawn(fun () -> receive after 500 -> ok end end),
-    ?line T3 = erlang:start_timer(10000, P2, "hej"),
-    ?line T4 = erlang:send_after(10000, P2, "hej"),
-    ?line true = Mem < mem(),
+    ?line P2 = spawn(fun () -> receive after (?SHORT_TIMEOUT div 10) -> ok end end),
+    ?line T3 = erlang:start_timer(?SHORT_TIMEOUT*2, P2, "hej"),
+    ?line T4 = erlang:send_after(?SHORT_TIMEOUT*2, P2, "hej"),
+    ?line true = mem_larger_than(Mem),
     ?line true = is_integer(erlang:read_timer(T3)),
     ?line true = is_integer(erlang:read_timer(T4)),
     ?line wait_until(fun () -> process_is_cleaned_up(P2) end),
@@ -259,21 +305,22 @@ cleanup_test(Config) when is_list(Config) ->
     ?line false = erlang:read_timer(T4),
     ?line Mem = mem(),
     %% Cancel timer
-    ?line P3 = spawn(fun () -> receive after 20000 -> ok end end),
-    ?line T5 = erlang:start_timer(10000, P3, "hej"),
-    ?line T6 = erlang:send_after(10000, P3, "hej"),
-    ?line true = Mem < mem(),
+    ?line P3 = spawn(fun () -> receive after ?SHORT_TIMEOUT*4 -> ok end end),
+    ?line T5 = erlang:start_timer(?SHORT_TIMEOUT*2, P3, "hej"),
+    ?line T6 = erlang:send_after(?SHORT_TIMEOUT*2, P3, "hej"),
+    ?line true = mem_larger_than(Mem),
     ?line true = is_integer(erlang:cancel_timer(T5)),
     ?line true = is_integer(erlang:cancel_timer(T6)),
     ?line false = erlang:read_timer(T5),
     ?line false = erlang:read_timer(T6),
     ?line exit(P3, kill),
+    ?line wait_until(fun () -> process_is_cleaned_up(P3) end),
     ?line Mem = mem(),
     %% Timeout
     ?line Ref = make_ref(),
-    ?line T7 = erlang:start_timer(500, self(), Ref),
-    ?line T8 = erlang:send_after(500, self(), Ref),
-    ?line true = Mem < mem(),
+    ?line T7 = erlang:start_timer(?SHORT_TIMEOUT+1, self(), Ref),
+    ?line T8 = erlang:send_after(?SHORT_TIMEOUT+1, self(), Ref),
+    ?line true = mem_larger_than(Mem),
     ?line true = is_integer(erlang:read_timer(T7)),
     ?line true = is_integer(erlang:read_timer(T8)),
     ?line receive {timeout, T7, Ref} -> ok end,
@@ -423,15 +470,12 @@ evil_recv_timeouts(TOs, N, M) ->
 registered_process(doc) -> [];
 registered_process(suite) -> [];
 registered_process(Config) when is_list(Config) ->
-    {skipped, "Test needs to be UPDATED for new timer implementation"}.
-
-registered_process_test(Config)  when is_list(Config) ->
     ?line Mem = mem(),
     %% Cancel
-    ?line T1 = erlang:start_timer(500, ?MODULE, "hej"),
-    ?line T2 = erlang:send_after(500, ?MODULE, "hej"),
+    ?line T1 = erlang:start_timer(?SHORT_TIMEOUT+1, ?MODULE, "hej"),
+    ?line T2 = erlang:send_after(?SHORT_TIMEOUT+1, ?MODULE, "hej"),
     ?line undefined = whereis(?MODULE),
-    ?line true = Mem < mem(),
+    ?line true = mem_larger_than(Mem),
     ?line true = is_integer(erlang:cancel_timer(T1)),
     ?line true = is_integer(erlang:cancel_timer(T2)),
     ?line false = erlang:read_timer(T1),
@@ -439,10 +483,10 @@ registered_process_test(Config)  when is_list(Config) ->
     ?line Mem = mem(),
     %% Timeout register after start
     ?line Ref1 = make_ref(),
-    ?line T3 = erlang:start_timer(500, ?MODULE, Ref1),
-    ?line T4 = erlang:send_after(500, ?MODULE, Ref1),
+    ?line T3 = erlang:start_timer(?SHORT_TIMEOUT+1, ?MODULE, Ref1),
+    ?line T4 = erlang:send_after(?SHORT_TIMEOUT+1, ?MODULE, Ref1),
     ?line undefined = whereis(?MODULE),
-    ?line true = Mem < mem(),
+    ?line true = mem_larger_than(Mem),
     ?line true = is_integer(erlang:read_timer(T3)),
     ?line true = is_integer(erlang:read_timer(T4)),
     ?line true = register(?MODULE, self()),
@@ -451,9 +495,9 @@ registered_process_test(Config)  when is_list(Config) ->
     ?line Mem = mem(),
     %% Timeout register before start
     ?line Ref2 = make_ref(),
-    ?line T5 = erlang:start_timer(500, ?MODULE, Ref2),
-    ?line T6 = erlang:send_after(500, ?MODULE, Ref2),
-    ?line true = Mem < mem(),
+    ?line T5 = erlang:start_timer(?SHORT_TIMEOUT+1, ?MODULE, Ref2),
+    ?line T6 = erlang:send_after(?SHORT_TIMEOUT+1, ?MODULE, Ref2),
+    ?line true = mem_larger_than(Mem),
     ?line true = is_integer(erlang:read_timer(T5)),
     ?line true = is_integer(erlang:read_timer(T6)),
     ?line receive {timeout, T5, Ref2} -> ok end,
@@ -462,19 +506,135 @@ registered_process_test(Config)  when is_list(Config) ->
     ?line true = unregister(?MODULE),
     ?line ok.
 
-mem() ->
-    TSrvs = erts_internal:get_bif_timer_servers(),
-    lists:foldl(fun (Tab, Sz) ->
-			case lists:member(ets:info(Tab, owner), TSrvs) of
-			    true ->
-				ets:info(Tab, memory) + Sz;
-			    false ->
-				Sz
-			end
-		end,
-		0,
-		ets:all())*erlang:system_info({wordsize,external}).
-					    
+same_time_yielding(Config) when is_list(Config) ->
+    Mem = mem(),
+    SchdlrsOnln = erlang:system_info(schedulers_online),
+    Tmo = erlang:monotonic_time(milli_seconds) + 3000,
+    Tmrs = lists:map(fun (I) ->
+			     process_flag(scheduler, (I rem SchdlrsOnln) + 1),
+			     erlang:start_timer(Tmo, self(), hej, [{abs, true}])
+		     end,
+		     lists:seq(1, (?TIMEOUT_YIELD_LIMIT*3+1)*SchdlrsOnln)),
+    true = mem_larger_than(Mem),
+    lists:foreach(fun (Tmr) -> receive {timeout, Tmr, hej} -> ok end end, Tmrs),
+    Done = erlang:monotonic_time(milli_seconds),
+    true = Done >= Tmo,
+    case erlang:system_info(build_type) of
+	opt -> true = Done < Tmo + 200;
+	_ -> true = Done < Tmo + 1000
+    end,
+    Mem = mem(),
+    ok.
+
+same_time_yielding_with_cancel(Config) when is_list(Config) ->
+    same_time_yielding_with_cancel_test(false, false).
+
+same_time_yielding_with_cancel_other(Config) when is_list(Config) ->
+    same_time_yielding_with_cancel_test(true, false).
+
+same_time_yielding_with_cancel_other_accessor(Config) when is_list(Config) ->
+    same_time_yielding_with_cancel_test(true, true).
+
+do_cancel_tmrs(Tmo, Tmrs, Tester) ->
+    BeginCancel = erlang:convert_time_unit(Tmo,
+					   milli_seconds,
+					   micro_seconds) - 100,
+    busy_wait_until(fun () ->
+			    erlang:monotonic_time(micro_seconds) >= BeginCancel
+		    end),
+    lists:foreach(fun (Tmr) ->
+			  erlang:cancel_timer(Tmr,
+					      [{async, true},
+					       {info, true}])
+		  end, Tmrs),
+    case Tester == self() of
+	true -> ok;
+	false -> forward_msgs(Tester)
+    end.
+
+same_time_yielding_with_cancel_test(Other, Accessor) ->
+    Mem = mem(),
+    SchdlrsOnln = erlang:system_info(schedulers_online),
+    Tmo = erlang:monotonic_time(milli_seconds) + 3000,
+    Tester = self(),
+    Cancelor = case Other of
+		   false ->
+		       Tester;
+		   true ->
+		       spawn(fun () ->
+				     receive
+					 {timers, Tmrs} ->
+					     do_cancel_tmrs(Tmo, Tmrs, Tester)
+				     end
+			     end)
+	       end,
+    Opts = case Accessor of
+	       false -> [{abs, true}];
+	       true -> [{accessor, Cancelor}, {abs, true}]
+	   end,
+    Tmrs = lists:map(fun (I) ->
+			     process_flag(scheduler, (I rem SchdlrsOnln) + 1),
+			     erlang:start_timer(Tmo, self(), hej, Opts)
+		     end,
+		     lists:seq(1, (?TIMEOUT_YIELD_LIMIT*3+1)*SchdlrsOnln)),
+    true = mem_larger_than(Mem),
+    case Other of
+	false ->
+	    do_cancel_tmrs(Tmo, Tmrs, Tester);
+	true ->
+	    Cancelor ! {timers, Tmrs}
+    end,
+    {Tmos, Cncls} = lists:foldl(fun (Tmr, {T, C}) ->
+					receive
+					    {timeout, Tmr, hej} ->
+						receive
+						    {cancel_timer, Tmr, Info} ->
+							false = Info,
+							{T+1, C}
+						end;
+					    {cancel_timer, Tmr, false} ->
+						receive
+						    {timeout, Tmr, hej} ->
+							{T+1, C}
+						end;
+					    {cancel_timer, Tmr, TimeLeft} ->
+						true = is_integer(TimeLeft),
+						{T, C+1}
+					end
+				end,
+				{0, 0},
+				Tmrs),
+    io:format("Timeouts: ~p Cancels: ~p~n", [Tmos, Cncls]),
+    Mem = mem(),
+    case Other of
+	true -> exit(Cancelor, bang);
+	false -> ok
+    end,
+    {comment,
+     "Timeouts: " ++ integer_to_list(Tmos) ++ " Cancels: "
+     ++ integer_to_list(Cncls)}.
+
+auto_cancel_yielding(Config) when is_list(Config) ->
+    Mem = mem(),
+    SchdlrsOnln = erlang:system_info(schedulers_online),
+    P = spawn(fun () ->
+		      lists:foreach(
+			fun (I) ->
+				process_flag(scheduler, (I rem SchdlrsOnln)+1),
+				erlang:start_timer((1 bsl 28)+I*10, self(), hej)
+			end,
+			lists:seq(1,
+				  ((?AUTO_CANCEL_YIELD_LIMIT*3+1)
+				   *SchdlrsOnln))),
+		      receive after infinity -> ok end
+	      end),
+    true = mem_larger_than(Mem),
+    exit(P, bang),
+    wait_until(fun () -> process_is_cleaned_up(P) end),
+    receive after 1000 -> ok end,
+    Mem = mem(),
+    ok.
+
 process_is_cleaned_up(P) when is_pid(P) ->
     undefined == erts_debug:get_internal_state({process_status, P}).
 
@@ -484,6 +644,19 @@ wait_until(Pred) when is_function(Pred) ->
 	_ -> receive after 50 -> ok end, wait_until(Pred)
     end.
 
+busy_wait_until(Pred) when is_function(Pred) ->
+    case catch Pred() of
+	true -> ok;
+	_ -> busy_wait_until(Pred)
+    end.
+
+forward_msgs(To) ->
+    receive
+	Msg ->
+	    To ! Msg
+    end,
+    forward_msgs(To).
+
 get(Time, Msg) ->
     receive 
 	Msg ->
@@ -566,5 +739,58 @@ type(X) when is_port(X) -> {port, node(X)};
 type(X) when is_binary(X) -> binary;
 type(X) when is_atom(X) -> atom;
 type(_) -> unknown.
-    
 
+
+mem_larger_than(no_fix_alloc) ->
+    true;
+mem_larger_than(Mem) ->
+    mem() > Mem.
+
+mem() ->
+    erts_debug:set_internal_state(wait, deallocations),
+    erts_debug:set_internal_state(wait, deallocations),
+    case mem_get() of
+	{-1, -1} -> no_fix_alloc;
+	{A, U} -> io:format("mem = ~p ~p~n", [A, U]), U
+    end.
+
+mem_get() ->
+    % Bif timer memory
+    Ref = make_ref(),
+    erlang:system_info({memory_internal, Ref, [fix_alloc]}),
+    mem_recv(erlang:system_info(schedulers), Ref, {0, 0}).
+
+mem_recv(0, _Ref, AU) ->
+    AU;
+mem_recv(N, Ref, AU) ->
+    receive
+	{Ref, _, IL} ->
+	    mem_recv(N-1, Ref, mem_parse_ilists(IL, AU))
+    end.
+
+
+mem_parse_ilists([], AU) ->
+    AU;
+mem_parse_ilists([I|Is], AU) ->
+    mem_parse_ilists(Is, mem_parse_ilist(I, AU)).
+
+mem_parse_ilist({fix_alloc, false}, _) ->
+    {-1, -1};
+mem_parse_ilist({fix_alloc, _, IDL}, {A, U}) ->
+    case lists:keyfind(fix_types, 1, IDL) of
+	{fix_types, TL} ->
+	    {ThisA, ThisU} = mem_get_btm_aus(TL, 0, 0),
+	    {ThisA + A, ThisU + U};
+	{fix_types, Mask, TL} ->
+	    {ThisA, ThisU} = mem_get_btm_aus(TL, 0, 0),
+	    {(ThisA + A) band Mask , (ThisU + U) band Mask}
+    end.
+
+mem_get_btm_aus([], A, U) ->
+    {A, U};
+mem_get_btm_aus([{BtmType, BtmA, BtmU} | Types],
+	    A, U) when BtmType == bif_timer;
+		       BtmType == accessor_bif_timer ->
+    mem_get_btm_aus(Types, BtmA+A, BtmU+U);
+mem_get_btm_aus([_|Types], A, U) ->
+    mem_get_btm_aus(Types, A, U).