Mercurial > libjeffpc
changeset 157:dbfb30f43dae
val: preallocate all possible bool vals
Since there are only two possible bool vals, we can preallocate all of them
and then just return the right one when a new bool val is requested -
avoiding a trip into the memory allocator.
One of the consumers of libjeffpc saw almost a 1% reduction in struct val
allocations during startup:
cache buf buf buf buf memory alloc alloc
name size in use in ptc total in use succeed fail
------------------------- ------ ------- ------- ------- ------- --------- -----
val-cache (before) 20 0 - 845 20K 24494 0
val-cache (after) 20 0 - 507 12K 24258 0
Note: This consumer is not a heavy user of VT_BOOL values.
Signed-off-by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
| author | Josef 'Jeff' Sipek <jeffpc@josefsipek.net> |
|---|---|
| date | Tue, 11 Apr 2017 11:21:06 -0400 |
| parents | 9e156cc8bdb8 |
| children | 7cd03c69d379 |
| files | include/jeffpc/val.h val.c |
| diffstat | 2 files changed, 28 insertions(+), 8 deletions(-) [+] |
line wrap: on
line diff
--- a/include/jeffpc/val.h Tue Apr 11 11:21:00 2017 -0400 +++ b/include/jeffpc/val.h Tue Apr 11 11:21:06 2017 -0400 @@ -127,13 +127,8 @@ _x; \ }) -#define VAL_ALLOC_BOOL(v) \ - ({ \ - struct val *_x; \ - _x = val_alloc_bool(v); \ - ASSERT(_x); \ - _x; \ - }) +/* never fails */ +#define VAL_ALLOC_BOOL(v) val_alloc_bool(v) #define VAL_ALLOC_CONS(head, tail) \ ({ \
--- a/val.c Tue Apr 11 11:21:00 2017 -0400 +++ b/val.c Tue Apr 11 11:21:06 2017 -0400 @@ -33,6 +33,16 @@ #include <jeffpc/jeffpc.h> #include <jeffpc/error.h> +#define INIT_STATIC_VAL(t, memb, val) \ + { \ + .type = (t), \ + .static_alloc = true, \ + .memb = (val), \ + } + +static const struct val val_true = INIT_STATIC_VAL(VT_BOOL, b, true); +static const struct val val_false = INIT_STATIC_VAL(VT_BOOL, b, false); + static umem_cache_t *val_cache; void init_val_subsys(void) @@ -98,9 +108,24 @@ DEF_VAL_SET(int, VT_INT, i, uint64_t) DEF_VAL_SET(str, VT_STR, str, struct str *) DEF_VAL_SET(sym, VT_SYM, str, struct str *) -DEF_VAL_SET(bool, VT_BOOL, b, bool) DEF_VAL_SET(char, VT_CHAR, i, uint64_t) +struct val *val_alloc_bool(bool b) +{ + const struct val *ret; + + ret = b ? &val_true : &val_false; + + /* + * Cast away the const - we define the static as const to get it + * into .rodata, but we have to drop the const since everything + * expects struct val to be writable (because refcounts modify it). + * In this case, we won't get any modifications because we're marked + * as static. + */ + return (struct val *) ret; +} + struct val *val_alloc_cons(struct val *head, struct val *tail) { struct val *val;