erts: Change ETS hash load factor

from 700% to 200%

2 files changed, 18 insertions, 17 deletions

diff --git a/erts/emulator/beam/erl_db_hash.c b/erts/emulator/beam/erl_db_hash.c
index 74979f984a..4c4ff9b470 100644
--- a/erts/emulator/beam/erl_db_hash.c
+++ b/erts/emulator/beam/erl_db_hash.c
@@ -95,7 +95,8 @@
 /* 
  * The following symbols can be manipulated to "tune" the linear hash array 
  */
-#define CHAIN_LEN 6                 /* Medium bucket chain len      */
+#define GROW_LIMIT(NACTIVE) ((NACTIVE)*2)
+#define SHRINK_LIMIT(NACTIVE) ((NACTIVE) / 2)
 
 /* Number of slots per segment */
 #define SEGSZ_EXP  8
@@ -463,7 +464,7 @@ db_finalize_dbterm_hash(int cret, DbUpdateHandle* handle);
 static ERTS_INLINE void try_shrink(DbTableHash* tb)
 {
     int nactive = NACTIVE(tb);
-    if (nactive > SEGSZ && NITEMS(tb) < (nactive * CHAIN_LEN)
+    if (nactive > SEGSZ && NITEMS(tb) < SHRINK_LIMIT(nactive)
 	&& !IS_FIXED(tb)) {
 	shrink(tb, nactive);
     }
@@ -862,7 +863,7 @@ Lnew:
     WUNLOCK_HASH(lck);
     {
 	int nactive = NACTIVE(tb);       
-	if (nitems > nactive * (CHAIN_LEN+1) && !IS_FIXED(tb)) {
+	if (nitems > GROW_LIMIT(nactive) && !IS_FIXED(tb)) {
 	    grow(tb, nactive);
 	}
     }
@@ -2250,12 +2251,12 @@ static int db_free_table_continue_hash(DbTable *tbl)
 
     done /= 2;
     while(tb->nslots != 0) {
-	free_seg(tb, 1);
+	done += 1 + SEGSZ/64 + free_seg(tb, 1);
 
 	/*
 	 * If we have done enough work, get out here.
 	 */
-	if (++done >= (DELETE_RECORD_LIMIT / CHAIN_LEN / SEGSZ)) {
+	if (done >= DELETE_RECORD_LIMIT) {
 	    return 0;	/* Not done */
 	}
     }
@@ -2871,7 +2872,7 @@ db_lookup_dbterm_hash(Process *p, DbTable *tbl, Eterm key, Eterm obj,
                 int nitems = erts_smp_atomic_inc_read_nob(&tb->common.nitems);
                 int nactive = NACTIVE(tb);
 
-                if (nitems > nactive * (CHAIN_LEN + 1) && !IS_FIXED(tb)) {
+                if (nitems > GROW_LIMIT(nactive) && !IS_FIXED(tb)) {
                     grow(tb, nactive);
                 }
             }
diff --git a/lib/stdlib/test/ets_SUITE.erl b/lib/stdlib/test/ets_SUITE.erl
index 8c1c625676..c065f4f22c 100644
--- a/lib/stdlib/test/ets_SUITE.erl
+++ b/lib/stdlib/test/ets_SUITE.erl
@@ -604,9 +604,9 @@ memory(Config) when is_list(Config) ->
 memory_do(Opts) ->
     L = [T1,T2,T3,T4] = fill_sets_int(1000,Opts),
     XR1 = case mem_mode(T1) of
-	      {normal,_} ->     {13836,13046,13046,13052}; %{13862,13072,13072,13078};
-	      {compressed,4} -> {11041,10251,10251,10252}; %{11067,10277,10277,10278};
-	      {compressed,8} -> {10050,9260,9260,9260} %{10076,9286,9286,9286}
+	      {normal,_} ->     {13836,13560,13560,13566}; %{13836,13046,13046,13052}
+	      {compressed,4} -> {11041,10865,10865,10866}; %{11041,10251,10251,10252}
+	      {compressed,8} -> {10050,9774,9774,9774} % {10050,9260,9260,9260}
 	  end,
     XRes1 = adjust_xmem(L, XR1),
     Res1 = {?S(T1),?S(T2),?S(T3),?S(T4)},
@@ -620,9 +620,9 @@ memory_do(Opts) ->
 		  end,
 		  L),
     XR2 = case mem_mode(T1) of
-	      {normal,_} ->     {13826,13037,13028,13034}; %{13852,13063,13054,13060};
-	      {compressed,4} -> {11031,10242,10233,10234}; %{11057,10268,10259,10260};
-	      {compressed,8} -> {10040,9251,9242,9242}     %10066,9277,9268,9268}
+	      {normal,_} ->     {13826,13551,13542,13548}; %{13826,13037,13028,13034};
+	      {compressed,4} -> {11031,10856,10747,10748}; %{11031,10242,10233,10234};
+	      {compressed,8} -> {10040,9765,9756,9756} %{10040,9251,9242,9242}
 	  end,
     XRes2 = adjust_xmem(L, XR2),
     Res2 = {?S(T1),?S(T2),?S(T3),?S(T4)},
@@ -636,9 +636,9 @@ memory_do(Opts) ->
 		  end,
 		  L),
     XR3 = case mem_mode(T1) of
-	      {normal,_} ->     {13816,13028,13010,13016}; %{13842,13054,13036,13042};
-	      {compressed,4} -> {11021,10233,10215,10216}; %{11047,10259,10241,10242};
-	      {compressed,8} -> {10030,9242,9224,9224} %{10056,9268,9250,9250}
+	      {normal,_} ->     {13816,13542,13524,13530}; %{13816,13028,13010,13016}
+	      {compressed,4} -> {11021,10747,10729,10730}; %{11021,10233,10215,10216}
+	      {compressed,8} -> {10030,9756,9738,9738}  %{10030,9242,9224,9224}
 	  end,
     XRes3 = adjust_xmem(L, XR3),
     Res3 = {?S(T1),?S(T2),?S(T3),?S(T4)},
@@ -5350,12 +5350,12 @@ verify_table_load(T) ->
     Stats = ets:info(T,stats),
     {Buckets,AvgLen,StdDev,ExpSD,_MinLen,_MaxLen,_} = Stats,
     ok = if
-	     AvgLen > 7 ->
+	     AvgLen > 2 ->
 		 io:format("Table overloaded: Stats=~p\n~p\n",
 			   [Stats, ets:info(T)]),
 		 false;
 
-	     Buckets>256, AvgLen < 6 ->
+	     Buckets>256, AvgLen < 0.5 ->
 		 io:format("Table underloaded: Stats=~p\n~p\n",
 			   [Stats, ets:info(T)]),
 		 false;