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authorErlang/OTP <[email protected]>2012-04-25 13:11:32 +0200
committerErlang/OTP <[email protected]>2012-04-25 13:11:32 +0200
commitc0e8ade45c9258678e489043a5fa40aa7bcee4d4 (patch)
treeb0a1f3fd737242375c0b46b346168b0a0e10f733 /erts/emulator
parent269c223d7bdf194cc3ea25d792328d8b502d4655 (diff)
parent342a41556fa6f148cbde18f65a4e44fd3ad9a3ee (diff)
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Merge branch 'rickard/no_ets_write_concurrency-r15b01/OTP-10048' into maint-r15
* rickard/no_ets_write_concurrency-r15b01/OTP-10048: Remove unnecessary memory barriers in ETS when no write_concurrency is used
Diffstat (limited to 'erts/emulator')
-rw-r--r--erts/emulator/beam/erl_db_hash.c63
1 files changed, 52 insertions, 11 deletions
diff --git a/erts/emulator/beam/erl_db_hash.c b/erts/emulator/beam/erl_db_hash.c
index c726be5fb4..2fea4671e1 100644
--- a/erts/emulator/beam/erl_db_hash.c
+++ b/erts/emulator/beam/erl_db_hash.c
@@ -105,7 +105,20 @@
#define NSEG_2 256 /* Size of second segment table */
#define NSEG_INC 128 /* Number of segments to grow after that */
-#define SEGTAB(tb) ((struct segment**)erts_smp_atomic_read_ddrb(&(tb)->segtab))
+#ifdef ERTS_SMP
+# define DB_USING_FINE_LOCKING(TB) (((TB))->common.type & DB_FINE_LOCKED)
+#else
+# define DB_USING_FINE_LOCKING(TB) 0
+#endif
+
+#ifdef ETHR_ORDERED_READ_DEPEND
+#define SEGTAB(tb) ((struct segment**) erts_smp_atomic_read_nob(&(tb)->segtab))
+#else
+#define SEGTAB(tb) \
+ (DB_USING_FINE_LOCKING(tb) \
+ ? ((struct segment**) erts_smp_atomic_read_ddrb(&(tb)->segtab)) \
+ : ((struct segment**) erts_smp_atomic_read_nob(&(tb)->segtab)))
+#endif
#define NACTIVE(tb) ((int)erts_smp_atomic_read_nob(&(tb)->nactive))
#define NITEMS(tb) ((int)erts_smp_atomic_read_nob(&(tb)->common.nitems))
@@ -122,7 +135,9 @@
*/
static ERTS_INLINE Uint hash_to_ix(DbTableHash* tb, HashValue hval)
{
- Uint mask = erts_smp_atomic_read_acqb(&tb->szm);
+ Uint mask = (DB_USING_FINE_LOCKING(tb)
+ ? erts_smp_atomic_read_acqb(&tb->szm)
+ : erts_smp_atomic_read_nob(&tb->szm));
Uint ix = hval & mask;
if (ix >= erts_smp_atomic_read_nob(&tb->nactive)) {
ix &= mask>>1;
@@ -319,7 +334,10 @@ struct ext_segment {
static ERTS_INLINE void SET_SEGTAB(DbTableHash* tb,
struct segment** segtab)
{
- erts_smp_atomic_set_wb(&tb->segtab, (erts_aint_t) segtab);
+ if (DB_USING_FINE_LOCKING(tb))
+ erts_smp_atomic_set_wb(&tb->segtab, (erts_aint_t) segtab);
+ else
+ erts_smp_atomic_set_nob(&tb->segtab, (erts_aint_t) segtab);
#ifdef VALGRIND
tb->top_ptr_to_segment_with_active_segtab = EXTSEG(segtab);
#endif
@@ -2501,6 +2519,28 @@ static Eterm build_term_list(Process* p, HashDbTerm* ptr1, HashDbTerm* ptr2,
return list;
}
+static ERTS_INLINE int
+begin_resizing(DbTableHash* tb)
+{
+ if (DB_USING_FINE_LOCKING(tb))
+ return !erts_smp_atomic_xchg_acqb(&tb->is_resizing, 1);
+ else {
+ if (erts_smp_atomic_read_nob(&tb->is_resizing))
+ return 0;
+ erts_smp_atomic_set_nob(&tb->is_resizing, 1);
+ return 1;
+ }
+}
+
+static ERTS_INLINE void
+done_resizing(DbTableHash* tb)
+{
+ if (DB_USING_FINE_LOCKING(tb))
+ erts_smp_atomic_set_relb(&tb->is_resizing, 0);
+ else
+ erts_smp_atomic_set_nob(&tb->is_resizing, 0);
+}
+
/* Grow table with one new bucket.
** Allocate new segment if needed.
*/
@@ -2513,9 +2553,8 @@ static void grow(DbTableHash* tb, int nactive)
int from_ix;
int szm;
- if (erts_smp_atomic_xchg_acqb(&tb->is_resizing, 1)) {
+ if (!begin_resizing(tb))
return; /* already in progress */
- }
if (NACTIVE(tb) != nactive) {
goto abort; /* already done (race) */
}
@@ -2547,9 +2586,12 @@ static void grow(DbTableHash* tb, int nactive)
}
erts_smp_atomic_inc_nob(&tb->nactive);
if (from_ix == 0) {
- erts_smp_atomic_set_relb(&tb->szm, szm);
+ if (DB_USING_FINE_LOCKING(tb))
+ erts_smp_atomic_set_relb(&tb->szm, szm);
+ else
+ erts_smp_atomic_set_nob(&tb->szm, szm);
}
- erts_smp_atomic_set_relb(&tb->is_resizing, 0);
+ done_resizing(tb);
/* Finally, let's split the bucket. We try to do it in a smart way
to keep link order and avoid unnecessary updates of next-pointers */
@@ -2581,7 +2623,7 @@ static void grow(DbTableHash* tb, int nactive)
return;
abort:
- erts_smp_atomic_set_relb(&tb->is_resizing, 0);
+ done_resizing(tb);
}
@@ -2590,9 +2632,8 @@ abort:
*/
static void shrink(DbTableHash* tb, int nactive)
{
- if (erts_smp_atomic_xchg_acqb(&tb->is_resizing, 1)) {
+ if (!begin_resizing(tb))
return; /* already in progress */
- }
if (NACTIVE(tb) == nactive) {
erts_smp_rwmtx_t* lck;
int src_ix = nactive - 1;
@@ -2639,7 +2680,7 @@ static void shrink(DbTableHash* tb, int nactive)
}
/*else already done */
- erts_smp_atomic_set_relb(&tb->is_resizing, 0);
+ done_resizing(tb);
}