erts: configure number of write_concurrency locks

Make it possible to change the number of write_concurrency locks to use. This
is usefull to change when you for some reason want to use more/less locks
per write_concurrency ets table. eg. OSs with a limit on how many mutexes
can exist at once.

2 files changed, 16 insertions, 0 deletions

diff --git a/erts/configure.in b/erts/configure.in
index 7ad0a6caf0..c964327ebc 100644
--- a/erts/configure.in
+++ b/erts/configure.in
@@ -426,6 +426,17 @@ AS_HELP_STRING([--enable-static-drivers], [comma seperated list of linked-in dri
 	       STATIC_DRIVERS=no)
 AC_SUBST(STATIC_DRIVERS)
 
+AC_ARG_WITH(ets-write-concurrency-locks,
+  AS_HELP_STRING([--with-ets-write-concurrency-locks={8,16,32,64,128,256}],
+                 [specify how many locks the write_concurrency option for ets should use.])
+  AS_HELP_STRING([--without-ets-write-concurrency-locks],
+                 [use the default number of write_concurrency locks (default)]))
+
+if test X"$with_ets_write_concurrency_locks" != X""; then
+   AC_DEFINE_UNQUOTED(ERTS_DB_HASH_LOCK_CNT,$with_ets_write_concurrency_locks,
+		      [Define to override the default number of write_concurrency locks])
+fi
+
 dnl ----------------------------------------------------------------------
 dnl Checks for programs.
 dnl ----------------------------------------------------------------------
diff --git a/erts/emulator/beam/erl_db_hash.h b/erts/emulator/beam/erl_db_hash.h
index d17bd9f693..908cec11d4 100644
--- a/erts/emulator/beam/erl_db_hash.h
+++ b/erts/emulator/beam/erl_db_hash.h
@@ -33,7 +33,12 @@ typedef struct hash_db_term {
     DbTerm dbterm;         /* The actual term */
 } HashDbTerm;
 
+#ifdef ERTS_DB_HASH_LOCK_CNT
+#define DB_HASH_LOCK_CNT ERTS_DB_HASH_LOCK_CNT
+#else
 #define DB_HASH_LOCK_CNT 64
+#endif
+
 typedef struct db_table_hash_fine_locks {
     union {
 	erts_smp_rwmtx_t lck;