erts: Add system_flags(erts_alloc,"+M?sbct *")

to change sbct limit in runtime for chosen allocator type.

With great power comes great responsibility.

10 files changed, 242 insertions, 35 deletions

diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 24a091073d..5f3652eeb3 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -6707,6 +6707,23 @@ ok
 
     <func>
       <name name="system_flag" arity="2" clause_i="4"/>
+      <fsummary>Set system flag for erts_alloc.</fsummary>
+      <desc>
+        <p>Sets system flags for
+	<seealso marker="erts:erts_alloc"><c>erts_alloc(3)</c></seealso>.
+        <c><anno>Alloc</anno></c> is the allocator to affect, for example
+	<c>binary_alloc</c>. <c><anno>F</anno></c> is the flag to change and
+	<c><anno>V</anno></c> is the new value.</p>
+	<p>Only a subset of all <c>erts_alloc</c> flags can be changed
+	at run time. This subset is currently only the flag
+	<seealso marker="erts:erts_alloc#M_sbct"><c>sbct</c></seealso>.</p>
+        <p>Returns <c>ok</c> if the flag was set or <c>notsup</c> if not
+	supported by <c>erts_alloc</c>.</p>
+      </desc>
+    </func>
+
+    <func>
+      <name name="system_flag" arity="2" clause_i="5"/>
       <fsummary>Set system flag fullsweep_after.</fsummary>
       <desc>
         <p>Sets system flag <c>fullsweep_after</c>.
@@ -6725,7 +6742,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="5"/>
+      <name name="system_flag" arity="2" clause_i="6"/>
       <fsummary>Set system flag microstate_accounting.</fsummary>
       <desc>
         <p><marker id="system_flag_microstate_accounting"></marker>
@@ -6738,7 +6755,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="6"/>
+      <name name="system_flag" arity="2" clause_i="7"/>
       <fsummary>Set system flag min_heap_size.</fsummary>
       <desc>
         <p>Sets the default minimum heap size for processes. The size
@@ -6753,7 +6770,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="7"/>
+      <name name="system_flag" arity="2" clause_i="8"/>
       <fsummary>Set system flag min_bin_vheap_size.</fsummary>
       <desc>
         <p>Sets the default minimum binary virtual heap size for
@@ -6770,7 +6787,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="8"/>
+      <name name="system_flag" arity="2" clause_i="9"/>
       <fsummary>Set system flag max_heap_size.</fsummary>
       <type name="max_heap_size"/>
       <desc>
@@ -6788,7 +6805,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="9"/>
+      <name name="system_flag" arity="2" clause_i="10"/>
       <fsummary>Set system flag multi_scheduling.</fsummary>
       <desc>
         <p><marker id="system_flag_multi_scheduling"></marker>
@@ -6843,7 +6860,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="10"/>
+      <name name="system_flag" arity="2" clause_i="11"/>
       <fsummary>Set system flag scheduler_bind_type.</fsummary>
       <type name="scheduler_bind_type"/>
       <desc>
@@ -6969,7 +6986,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="11"/>
+      <name name="system_flag" arity="2" clause_i="12"/>
       <fsummary>Set system flag scheduler_wall_time.</fsummary>
       <desc>
         <p><marker id="system_flag_scheduler_wall_time"></marker>
@@ -6981,7 +6998,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="12"/>
+      <name name="system_flag" arity="2" clause_i="13"/>
       <fsummary>Set system flag schedulers_online.</fsummary>
       <desc>
         <p><marker id="system_flag_schedulers_online"></marker>
@@ -7009,7 +7026,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="13"/>
+      <name name="system_flag" arity="2" clause_i="14"/>
       <fsummary>Set system flag trace_control_word.</fsummary>
       <desc>
         <p>Sets the value of the node trace control word to
@@ -7023,7 +7040,7 @@ ok
     </func>
 
     <func>
-      <name name="system_flag" arity="2" clause_i="14"/>
+      <name name="system_flag" arity="2" clause_i="15"/>
       <fsummary>Finalize the time offset.</fsummary>
       <desc>
         <p><marker id="system_flag_time_offset"></marker>
diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index 2b66bf6f4e..6adb244eb7 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -560,6 +560,7 @@ atom running_procs
 atom runtime
 atom safe
 atom save_calls
+atom sbct
 atom scheduler 
 atom scheduler_id
 atom schedulers_online
diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index d9048065c8..3c44573c24 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -4706,6 +4706,8 @@ BIF_RETTYPE system_flag_2(BIF_ALIST_2)
 	    "scheduled for removal in Erlang/OTP 18. For more\n"
 	    "information see the erlang:system_flag/2 documentation.\n");
 	return erts_bind_schedulers(BIF_P, BIF_ARG_2);
+    } else if (ERTS_IS_ATOM_STR("erts_alloc", BIF_ARG_1)) {
+        return erts_alloc_set_dyn_param(BIF_P, BIF_ARG_2);
     }
     error:
     BIF_ERROR(BIF_P, BADARG);
diff --git a/erts/emulator/beam/erl_alloc.c b/erts/emulator/beam/erl_alloc.c
index 67cd3afb25..625aa98edf 100644
--- a/erts/emulator/beam/erl_alloc.c
+++ b/erts/emulator/beam/erl_alloc.c
@@ -1272,22 +1272,32 @@ get_bool_value(char *param_end, char** argv, int* ip)
     return -1;
 }
 
+static Uint kb_to_bytes(Sint kb, Uint *bytes)
+{
+    const Uint max = ((~((Uint) 0))/1024) + 1;
+
+    if (kb < 0 || (Uint)kb > max)
+        return 0;
+    if ((Uint)kb == max)
+        *bytes = ~((Uint) 0);
+    else
+        *bytes = ((Uint) kb)*1024;
+    return 1;
+}
+
 static Uint
 get_kb_value(char *param_end, char** argv, int* ip)
 {
     Sint tmp;
-    Uint max = ((~((Uint) 0))/1024) + 1;
+    Uint bytes = 0;
     char *rest;
     char *param = argv[*ip]+1;
     char *value = get_value(param_end, argv, ip);
     errno = 0;
     tmp = (Sint) ErtsStrToSint(value, &rest, 10);
-    if (errno != 0 || rest == value || tmp < 0 || max < ((Uint) tmp))
+    if (errno != 0 || rest == value || !kb_to_bytes(tmp, &bytes))
 	bad_value(param, param_end, value);
-    if (max == (Uint) tmp)
-	return ~((Uint) 0);
-    else
-	return ((Uint) tmp)*1024;
+    return bytes;
 }
 
 static UWord
@@ -3486,6 +3496,65 @@ erts_request_alloc_info(struct process *c_p,
     return 1;
 }
 
+Eterm erts_alloc_set_dyn_param(Process* c_p, Eterm tuple)
+{
+    ErtsAllocatorThrSpec_t *tspec;
+    ErtsAlcType_t ai;
+    Allctr_t* allctr;
+    Eterm* tp;
+    Eterm res;
+
+    if (!is_tuple_arity(tuple, 3))
+        goto badarg;
+
+    tp = tuple_val(tuple);
+
+    /*
+     * Ex: {ets_alloc, sbct, 256000}
+     */
+    if (!is_atom(tp[1]) || !is_atom(tp[2]) || !is_integer(tp[3]))
+        goto badarg;
+
+    for (ai = ERTS_ALC_A_MIN; ai <= ERTS_ALC_A_MAX; ai++)
+        if (erts_is_atom_str(erts_alc_a2ad[ai], tp[1], 0))
+            break;
+
+    if (ai > ERTS_ALC_A_MAX)
+        goto badarg;
+
+    if (!erts_allctrs_info[ai].enabled ||
+        !erts_allctrs_info[ai].alloc_util) {
+        return am_notsup;
+    }
+
+    if (tp[2] == am_sbct) {
+        Uint sbct;
+        int i, ok;
+
+        if (!term_to_Uint(tp[3], &sbct))
+            goto badarg;
+
+        tspec = &erts_allctr_thr_spec[ai];
+        if (tspec->enabled) {
+            ok = 0;
+            for (i = 0; i < tspec->size; i++) {
+                allctr = tspec->allctr[i];
+                ok |= allctr->try_set_dyn_param(allctr, am_sbct, sbct);
+            }
+        }
+        else {
+            allctr = erts_allctrs_info[ai].extra;
+            ok = allctr->try_set_dyn_param(allctr, am_sbct, sbct);
+        }
+        return ok ? am_ok : am_notsup;
+    }
+    return am_notsup;
+
+badarg:
+    ERTS_BIF_PREP_ERROR(res, c_p, EXC_BADARG);
+    return res;
+}
+
 /* 
  * The allocator wrapper prelocking stuff below is about the locking order.
  * It only affects wrappers (erl_mtrace.c and erl_instrument.c) that keep locks
diff --git a/erts/emulator/beam/erl_alloc.h b/erts/emulator/beam/erl_alloc.h
index 56a3b73bf9..33a9fa0bac 100644
--- a/erts/emulator/beam/erl_alloc.h
+++ b/erts/emulator/beam/erl_alloc.h
@@ -173,6 +173,8 @@ __decl_noreturn void erts_realloc_n_enomem(ErtsAlcType_t,void*,Uint)
 __decl_noreturn void erts_alc_fatal_error(int,int,ErtsAlcType_t,...)	
      __noreturn;
 
+Eterm erts_alloc_set_dyn_param(struct process*, Eterm);
+
 /* --- DO *NOT* USE THESE DEPRECATED FUNCTIONS ---    Instead use:       */
 void *safe_alloc(Uint)               __deprecated; /* erts_alloc()       */
 void *safe_realloc(void *, Uint)     __deprecated; /* erts_realloc()     */
diff --git a/erts/emulator/beam/erl_alloc_util.c b/erts/emulator/beam/erl_alloc_util.c
index 016d85fe2a..0bf95a65be 100644
--- a/erts/emulator/beam/erl_alloc_util.c
+++ b/erts/emulator/beam/erl_alloc_util.c
@@ -4226,7 +4226,6 @@ static struct {
     Eterm e;
     Eterm t;
     Eterm ramv;
-    Eterm sbct;
 #if HAVE_ERTS_MSEG
     Eterm asbcst;
     Eterm rsbcst;
@@ -4318,7 +4317,6 @@ init_atoms(Allctr_t *allctr)
 	AM_INIT(e);
 	AM_INIT(t);
 	AM_INIT(ramv);
-	AM_INIT(sbct);
 #if HAVE_ERTS_MSEG
 	AM_INIT(asbcst);
 	AM_INIT(rsbcst);
@@ -5011,7 +5009,7 @@ info_options(Allctr_t *allctr,
 		 bld_uint(hpp, szp, allctr->mseg_opt.abs_shrink_th));
 #endif
 	add_2tup(hpp, szp, &res,
-		 am.sbct,
+		 am_sbct,
 		 bld_uint(hpp, szp, allctr->sbc_threshold));
 	add_2tup(hpp, szp, &res, am.ramv, allctr->ramv ? am_true : am_false);
 	add_2tup(hpp, szp, &res, am.t, (allctr->t ? am_true : am_false));
@@ -5974,6 +5972,37 @@ erts_alcu_realloc_mv_thr_pref(ErtsAlcType_t type, void *extra,
 
 #endif
 
+static Uint adjust_sbct(Allctr_t* allctr, Uint sbct)
+{
+#ifndef ARCH_64
+    if (sbct > 0) {
+	Uint max_mbc_block_sz = UNIT_CEILING(sbct - 1 + ABLK_HDR_SZ);
+	if (max_mbc_block_sz + UNIT_FLOOR(allctr->min_block_size - 1) > MBC_ABLK_SZ_MASK
+	    || max_mbc_block_sz < sbct) { /* wrap around */
+	    /*
+	     * By limiting sbc_threshold to (hard limit - min_block_size)
+	     * we avoid having to split off free "residue blocks"
+	     * smaller than min_block_size.
+	     */
+	    max_mbc_block_sz = MBC_ABLK_SZ_MASK - UNIT_FLOOR(allctr->min_block_size - 1);
+	    sbct = max_mbc_block_sz - ABLK_HDR_SZ + 1;
+	}
+    }
+#endif
+    return sbct;
+}
+
+int erts_alcu_try_set_dyn_param(Allctr_t* allctr, Eterm param, Uint value)
+{
+    const Uint MIN_DYN_SBCT = 4000;  /* a lame catastrophe prevention */
+
+    if (param == am_sbct && value >= MIN_DYN_SBCT) {
+        allctr->sbc_threshold = adjust_sbct(allctr, value);
+        return 1;
+    }
+    return 0;
+}
+
 /* ------------------------------------------------------------------------- */
 
 int
@@ -6089,22 +6118,7 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
     }
 #endif
 
-    allctr->sbc_threshold		= init->sbct;
-#ifndef ARCH_64
-    if (allctr->sbc_threshold > 0) {
-	Uint max_mbc_block_sz = UNIT_CEILING(allctr->sbc_threshold - 1 + ABLK_HDR_SZ); 
-	if (max_mbc_block_sz + UNIT_FLOOR(allctr->min_block_size - 1) > MBC_ABLK_SZ_MASK
-	    || max_mbc_block_sz < allctr->sbc_threshold) { /* wrap around */
-	    /* 
-	     * By limiting sbc_threshold to (hard limit - min_block_size)
-	     * we avoid having to split off free "residue blocks"
-	     * smaller than min_block_size.
-	     */
-	    max_mbc_block_sz = MBC_ABLK_SZ_MASK - UNIT_FLOOR(allctr->min_block_size - 1);
-	    allctr->sbc_threshold = max_mbc_block_sz - ABLK_HDR_SZ + 1;
-	}
-    }
-#endif
+    allctr->sbc_threshold = adjust_sbct(allctr, init->sbct);
 
 #if HAVE_ERTS_MSEG
     if (allctr->mseg_opt.abs_shrink_th > ~((UWord) 0) / 100)
@@ -6167,6 +6181,9 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
         allctr->sys_realloc = &erts_alcu_sys_realloc;
         allctr->sys_dealloc = &erts_alcu_sys_dealloc;
     }
+
+    allctr->try_set_dyn_param = &erts_alcu_try_set_dyn_param;
+
 #if HAVE_ERTS_MSEG
     if (init->mseg_alloc) {
         ASSERT(init->mseg_realloc && init->mseg_dealloc);
@@ -6181,6 +6198,7 @@ erts_alcu_start(Allctr_t *allctr, AllctrInit_t *init)
         allctr->mseg_realloc = &erts_alcu_mseg_realloc;
         allctr->mseg_dealloc = &erts_alcu_mseg_dealloc;
     }
+
     /* If a custom carrier alloc function is specified, make sure it's used */
     if (init->mseg_alloc && !init->sys_alloc) {
         allctr->crr_set_flgs = CFLG_FORCE_MSEG;
diff --git a/erts/emulator/beam/erl_alloc_util.h b/erts/emulator/beam/erl_alloc_util.h
index d2cdc3a320..6c0c5ca86a 100644
--- a/erts/emulator/beam/erl_alloc_util.h
+++ b/erts/emulator/beam/erl_alloc_util.h
@@ -227,6 +227,8 @@ void* erts_alcu_literal_32_sys_realloc(Allctr_t*, void *ptr, Uint *size_p, Uint
 void  erts_alcu_literal_32_sys_dealloc(Allctr_t*, void *ptr, Uint size, int superalign);
 #endif
 
+int erts_alcu_try_set_dyn_param(Allctr_t*, Eterm param, Uint value);
+
 #endif /* !ERL_ALLOC_UTIL__ */
 
 #if defined(GET_ERL_ALLOC_UTIL_IMPL) && !defined(ERL_ALLOC_UTIL_IMPL__)
@@ -616,6 +618,8 @@ struct Allctr_t_ {
     void*               (*sys_realloc)(Allctr_t *allctr, void *ptr, Uint *size_p, Uint old_size, int superalign);
     void                (*sys_dealloc)(Allctr_t *allctr, void *ptr, Uint size, int superalign);
 
+    int                 (*try_set_dyn_param)(Allctr_t*, Eterm param, Uint value);
+
     void		(*init_atoms)		(void);
 
 #ifdef ERTS_ALLOC_UTIL_HARD_DEBUG
diff --git a/erts/emulator/beam/erl_goodfit_alloc.c b/erts/emulator/beam/erl_goodfit_alloc.c
index 50aa41b4d2..a38f6c7daf 100644
--- a/erts/emulator/beam/erl_goodfit_alloc.c
+++ b/erts/emulator/beam/erl_goodfit_alloc.c
@@ -170,6 +170,7 @@ static void		unlink_free_block	(Allctr_t *, Block_t *);
 static void		update_last_aux_mbc	(Allctr_t *, Carrier_t *);
 static Eterm		info_options		(Allctr_t *, char *, fmtfn_t *,
 						 void *, Uint **, Uint *);
+static int        gfalc_try_set_dyn_param(Allctr_t*, Eterm param, Uint value);
 static void		init_atoms		(void);
 
 #ifdef ERTS_ALLOC_UTIL_HARD_DEBUG
@@ -250,6 +251,8 @@ erts_gfalc_start(GFAllctr_t *gfallctr,
     if (!erts_alcu_start(allctr, init))
 	return NULL;
 
+    allctr->try_set_dyn_param = gfalc_try_set_dyn_param;
+
     if (allctr->min_block_size != MIN_BLK_SZ)
 	return NULL;
 
@@ -584,6 +587,15 @@ info_options(Allctr_t *allctr,
     return res;
 }
 
+static int gfalc_try_set_dyn_param(Allctr_t* allctr, Eterm param, Uint value)
+{
+    if (param == am_sbct) {
+        /* Cannot change 'sbct' without rearranging buckets */
+        return 0;
+    }
+    return erts_alcu_try_set_dyn_param(allctr, param, value);
+}
+
 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
  * NOTE:  erts_gfalc_test() is only supposed to be used for testing.         *
  *                                                                           *
diff --git a/erts/emulator/test/alloc_SUITE.erl b/erts/emulator/test/alloc_SUITE.erl
index 61d2adcbca..e4b4465c60 100644
--- a/erts/emulator/test/alloc_SUITE.erl
+++ b/erts/emulator/test/alloc_SUITE.erl
@@ -31,6 +31,7 @@
 	 mseg_clear_cache/1,
 	 erts_mmap/1,
 	 cpool/1,
+         set_dyn_param/1,
 	 migration/1]).
 
 -include_lib("common_test/include/ct.hrl").
@@ -41,6 +42,7 @@ suite() ->
 
 all() -> 
     [basic, coalesce, threads, realloc_copy, bucket_index,
+     set_dyn_param,
      bucket_mask, rbtree, mseg_clear_cache, erts_mmap, cpool, migration].
 
 init_per_testcase(Case, Config) when is_list(Config) ->
@@ -145,6 +147,82 @@ erts_mmap_do(Config, SCO, SCRPM, SCRFSD) ->
     Result.
 
 
+%% Test erlang:system_flag(erts_alloc, ...)
+set_dyn_param(_Config) ->
+    {_, _, _, AlcList} = erlang:system_info(allocator),
+
+    {Enabled, Disabled, Others} =
+        lists:foldl(fun({sys_alloc,_}, {Es, Ds, Os}) ->
+                            {Es, [sys_alloc | Ds], Os};
+
+                       ({AT, Opts}, {Es, Ds, Os}) when is_list(Opts) ->
+                            case lists:keyfind(e, 1, Opts) of
+                                {e, true} ->
+                                    {[AT | Es], Ds, Os};
+                                {e, false} ->
+                                    {Es, [AT | Ds], Os};
+                                false ->
+                                    {Es, Ds, [AT | Os]}
+                            end;
+
+                       (_, Acc) -> Acc
+                    end,
+                    {[], [], []},
+                    AlcList),
+
+    Param = sbct,
+    lists:foreach(fun(AT) -> set_dyn_param_enabled(AT, Param) end,
+                  Enabled),
+
+    lists:foreach(fun(AT) ->
+                          Tpl = {AT, Param, 12345},
+                          io:format("~p\n", [Tpl]),
+                          notsup = erlang:system_flag(erts_alloc, Tpl)
+                  end,
+                  Disabled),
+
+    lists:foreach(fun(AT) ->
+                          Tpl = {AT, Param, 12345},
+                          io:format("~p\n", [Tpl]),
+                          {'EXIT',{badarg,_}} =
+                              (catch erlang:system_flag(erts_alloc, Tpl))
+                  end,
+                  Others),
+    ok.
+
+set_dyn_param_enabled(AT, Param) ->
+    OldVal = get_alc_param(AT, Param),
+
+    Val1 = OldVal div 2,
+    Tuple = {AT, Param, Val1},
+    io:format("~p\n", [Tuple]),
+    ok = erlang:system_flag(erts_alloc, Tuple),
+    Val1 = get_alc_param(AT, Param),
+
+    ok = erlang:system_flag(erts_alloc, {AT, Param, OldVal}),
+    OldVal = get_alc_param(AT, Param),
+    ok.
+
+get_alc_param(AT, Param) ->
+    lists:foldl(fun({instance,_,Istats}, Acc) ->
+                        {options,Opts} = lists:keyfind(options, 1, Istats),
+                        {Param,Val} = lists:keyfind(Param, 1, Opts),
+                        {as,Strategy} = lists:keyfind(as, 1, Opts),
+
+                        case {param_for_strat(Param, Strategy), Acc} of
+                            {false, _} -> Acc;
+                            {true, undefined} -> Val;
+                            {true, _} ->
+                                Val = Acc
+                        end
+                end,
+                undefined,
+                erlang:system_info({allocator, AT})).
+
+param_for_strat(sbct, gf) -> false;
+param_for_strat(_, _) -> true.
+
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%                                                                        %%
 %% Internal functions                                                     %%
diff --git a/erts/preloaded/src/erlang.erl b/erts/preloaded/src/erlang.erl
index 8771089b65..6030f7312d 100644
--- a/erts/preloaded/src/erlang.erl
+++ b/erts/preloaded/src/erlang.erl
@@ -2347,6 +2347,10 @@ subtract(_,_) ->
                                 OldDirtyCPUSchedulersOnline when
       DirtyCPUSchedulersOnline :: pos_integer(),
       OldDirtyCPUSchedulersOnline :: pos_integer();
+                        (erts_alloc, {Alloc, F, V}) -> ok | notsup when
+      Alloc :: atom(),
+      F :: atom(),
+      V :: integer();
                         (fullsweep_after, Number) -> OldNumber when
       Number :: non_neg_integer(),
       OldNumber :: non_neg_integer();