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author | Sverker Eriksson <sverker@erlang.org> | 2016-08-24 16:28:53 +0200 |
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committer | Sverker Eriksson <sverker@erlang.org> | 2016-09-19 15:50:14 +0200 |
commit | 0d7a001039dbcab096397f27213b518113a9e5d0 (patch) | |
tree | 9db4d9449114923697dac6808add0f1708c067f2 /erts/emulator/beam | |
parent | abc2f4fdae2d62b5d2843082dbb4437595973b38 (diff) | |
download | otp-0d7a001039dbcab096397f27213b518113a9e5d0.tar.gz otp-0d7a001039dbcab096397f27213b518113a9e5d0.tar.bz2 otp-0d7a001039dbcab096397f27213b518113a9e5d0.zip |
erts: Enable a smaller first hash segment for ets
Diffstat (limited to 'erts/emulator/beam')
-rw-r--r-- | erts/emulator/beam/erl_db_hash.c | 67 |
1 files changed, 41 insertions, 26 deletions
diff --git a/erts/emulator/beam/erl_db_hash.c b/erts/emulator/beam/erl_db_hash.c index 82f03e458a..2d24f438ca 100644 --- a/erts/emulator/beam/erl_db_hash.c +++ b/erts/emulator/beam/erl_db_hash.c @@ -89,10 +89,20 @@ */ #define CHAIN_LEN 6 /* Medium bucket chain len */ -/* Number of slots per segment */ -#define SEGSZ_EXP 8 -#define SEGSZ (1 << SEGSZ_EXP) -#define SEGSZ_MASK (SEGSZ-1) +/* +** We want the first mandatory segment to be small (to reduce minimal footprint) +** and larger extra segments (to reduce number of alloc/free calls). +*/ + +/* Number of slots in first segment */ +#define FIRST_SEGSZ_EXP 8 +#define FIRST_SEGSZ (1 << FIRST_SEGSZ_EXP) +#define FIRST_SEGSZ_MASK (FIRST_SEGSZ - 1) + +/* Number of slots per extra segment */ +#define EXT_SEGSZ_EXP 11 +#define EXT_SEGSZ (1 << EXT_SEGSZ_EXP) +#define EXT_SEGSZ_MASK (EXT_SEGSZ-1) #define NSEG_1 (ErtsSizeofMember(DbTableHash,first_segtab) / sizeof(struct segment*)) #define NSEG_2 256 /* Size of second segment table */ @@ -115,7 +125,9 @@ #define NACTIVE(tb) ((int)erts_smp_atomic_read_nob(&(tb)->nactive)) #define NITEMS(tb) ((int)erts_smp_atomic_read_nob(&(tb)->common.nitems)) -#define BUCKET(tb, i) SEGTAB(tb)[(i) >> SEGSZ_EXP]->buckets[(i) & SEGSZ_MASK] +#define SLOT_IX_TO_SEG_IX(i) (((i)+(EXT_SEGSZ-FIRST_SEGSZ)) >> EXT_SEGSZ_EXP) + +#define BUCKET(tb, i) SEGTAB(tb)[SLOT_IX_TO_SEG_IX(i)]->buckets[(i) & EXT_SEGSZ_MASK] /* * When deleting a table, the number of records to delete. @@ -422,7 +434,7 @@ 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 > FIRST_SEGSZ && NITEMS(tb) < (nactive * CHAIN_LEN) && !IS_FIXED(tb)) { shrink(tb, nactive); } @@ -621,17 +633,17 @@ int db_create_hash(Process *p, DbTable *tbl) { DbTableHash *tb = &tbl->hash; - erts_smp_atomic_init_nob(&tb->szm, SEGSZ_MASK); - erts_smp_atomic_init_nob(&tb->nactive, SEGSZ); + erts_smp_atomic_init_nob(&tb->szm, FIRST_SEGSZ_MASK); + erts_smp_atomic_init_nob(&tb->nactive, FIRST_SEGSZ); erts_smp_atomic_init_nob(&tb->fixdel, (erts_aint_t)NULL); erts_smp_atomic_init_nob(&tb->segtab, (erts_aint_t)NULL); SET_SEGTAB(tb, tb->first_segtab); tb->nsegs = NSEG_1; - tb->nslots = SEGSZ; + tb->nslots = FIRST_SEGSZ; tb->first_segtab[0] = (struct segment*) erts_db_alloc(ERTS_ALC_T_DB_SEG, (DbTable *) tb, - SIZEOF_SEGMENT(SEGSZ)); - sys_memset(tb->first_segtab[0], 0, SIZEOF_SEGMENT(SEGSZ)); + SIZEOF_SEGMENT(FIRST_SEGSZ)); + sys_memset(tb->first_segtab[0], 0, SIZEOF_SEGMENT(FIRST_SEGSZ)); #ifdef ERTS_SMP erts_smp_atomic_init_nob(&tb->is_resizing, 0); @@ -649,7 +661,7 @@ int db_create_hash(Process *p, DbTable *tbl) erts_smp_rwmtx_init_opt_x(&tb->locks->lck_vec[i].lck, &rwmtx_opt, "db_hash_slot", make_small(i)); } - /* This important property is needed to guarantee that the buckets + /* This important property is needed to guarantee the two buckets * involved in a grow/shrink operation it protected by the same lock: */ ASSERT(erts_smp_atomic_read_nob(&tb->nactive) % DB_HASH_LOCK_CNT == 0); @@ -2213,12 +2225,12 @@ static int db_free_table_continue_hash(DbTable *tbl) done /= 2; while(tb->nslots != 0) { - free_seg(tb, 1); + done += 1 + EXT_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 */ } } @@ -2406,9 +2418,10 @@ static struct ext_segtab* alloc_ext_segtab(DbTableHash* tb, unsigned seg_ix) */ static int alloc_seg(DbTableHash *tb) { - int seg_ix = tb->nslots >> SEGSZ_EXP; + int seg_ix = SLOT_IX_TO_SEG_IX(tb->nslots); struct segment** segtab; + ASSERT(seg_ix > 0); if (seg_ix == tb->nsegs) { /* New segtab needed */ struct ext_segtab* est = alloc_ext_segtab(tb, seg_ix); SET_SEGTAB(tb, est->segtab); @@ -2418,9 +2431,9 @@ static int alloc_seg(DbTableHash *tb) segtab = SEGTAB(tb); segtab[seg_ix] = (struct segment*) erts_db_alloc(ERTS_ALC_T_DB_SEG, (DbTable *) tb, - SIZEOF_SEGMENT(SEGSZ)); - sys_memset(segtab[seg_ix], 0, SIZEOF_SEGMENT(SEGSZ)); - tb->nslots += SEGSZ; + SIZEOF_SEGMENT(EXT_SEGSZ)); + sys_memset(segtab[seg_ix], 0, SIZEOF_SEGMENT(EXT_SEGSZ)); + tb->nslots += EXT_SEGSZ; return 1; } @@ -2438,9 +2451,10 @@ static void dealloc_ext_segtab(void* lop_data) */ static int free_seg(DbTableHash *tb, int free_records) { - const int seg_ix = (tb->nslots >> SEGSZ_EXP) - 1; + const int seg_ix = SLOT_IX_TO_SEG_IX(tb->nslots) - 1; struct segment** const segtab = SEGTAB(tb); struct segment* const segp = segtab[seg_ix]; + Uint seg_sz; int nrecords = 0; ASSERT(segp != NULL); @@ -2448,8 +2462,8 @@ static int free_seg(DbTableHash *tb, int free_records) if (free_records) #endif { - int i; - for (i=0; i<SEGSZ; ++i) { + int i = (seg_ix == 0) ? FIRST_SEGSZ : EXT_SEGSZ; + while (i--) { HashDbTerm* p = segp->buckets[i]; while(p != 0) { HashDbTerm* nxt = p->next; @@ -2495,13 +2509,14 @@ static int free_seg(DbTableHash *tb, int free_records) } } - erts_db_free(ERTS_ALC_T_DB_SEG, (DbTable *)tb, segp, SIZEOF_SEGMENT(SEGSZ)); + seg_sz = (seg_ix == 0) ? FIRST_SEGSZ : EXT_SEGSZ; + erts_db_free(ERTS_ALC_T_DB_SEG, (DbTable *)tb, segp, SIZEOF_SEGMENT(seg_sz)); #ifdef DEBUG if (seg_ix < tb->nsegs) SEGTAB(tb)[seg_ix] = NULL; #endif - tb->nslots -= SEGSZ; + tb->nslots -= seg_sz; ASSERT(tb->nslots >= 0); return nrecords; } @@ -2589,7 +2604,7 @@ static void grow(DbTableHash* tb, int nactive) /* Ensure that the slot nactive exists */ if (nactive == tb->nslots) { /* Time to get a new segment */ - ASSERT((nactive & SEGSZ_MASK) == 0); + ASSERT(((nactive-FIRST_SEGSZ) & EXT_SEGSZ_MASK) == 0); if (!alloc_seg(tb)) goto abort; } ASSERT(nactive < tb->nslots); @@ -2668,7 +2683,7 @@ static void shrink(DbTableHash* tb, int nactive) int dst_ix = src_ix & low_szm; ASSERT(dst_ix < src_ix); - ASSERT(nactive > SEGSZ); + ASSERT(nactive > FIRST_SEGSZ); lck = WLOCK_HASH(tb, dst_ix); /* Double check for racing table fixers */ if (!IS_FIXED(tb)) { @@ -2697,7 +2712,7 @@ static void shrink(DbTableHash* tb, int nactive) } WUNLOCK_HASH(lck); - if (tb->nslots - src_ix >= SEGSZ) { + if (tb->nslots - src_ix >= EXT_SEGSZ) { free_seg(tb, 0); } } |