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don't round to power-of-2 

Because rounding wastes memory when we use power-of-2 high-water marks.
This commit is contained in:
Heng Li 2017-06-26 22:10:45 -04:00
parent b56cd790f6
commit 0d03a43efd
1 changed files with 2 additions and 5 deletions
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7
kalloc.c
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@ -125,8 +125,6 @@ void kfree(void *_km, void *ap)
} else km->loop_head = p, q[1] = (size_t)p; /* in two cores, cannot be merged */
}
#define round_up(v) (--(v), (v)|=(v)>>1, (v)|=(v)>>2, (v)|=(v)>>4, (v)|=(v)>>8, (v)|=(v)>>16, (v)|=(v)>>32, ++(v))
void *krealloc(void *_km, void *ap, size_t n_bytes)
{
kmem_t *km = (kmem_t*)_km;
@ -139,9 +137,9 @@ void *krealloc(void *_km, void *ap, size_t n_bytes)
if (!ap) return kmalloc(km, n_bytes);
n_units = 1 + (n_bytes + sizeof(size_t) - 1) / sizeof(size_t);
p = (size_t*)ap - 1;
if (*p >= n_units) return ap;
if (*p >= n_units) return ap; /* TODO: this prevents shrinking */
q = (size_t*)kmalloc(km, n_bytes);
if (q != ap) memcpy(q, ap, (*p - 1) * sizeof(size_t));
memcpy(q, ap, (*p - 1) * sizeof(size_t));
kfree(km, ap);
return q;
}
@ -156,7 +154,6 @@ void *kmalloc(void *_km, size_t n_bytes)
/* "n_units" means the number of units. The size of one unit equals to sizeof(kheader_t).
* "1" is the kheader_t of a block, which is always required. */
n_units = 1 + (n_bytes + sizeof(size_t) - 1) / sizeof(size_t);
round_up(n_units);
if (!(q = km->loop_head)) { /* the first time when kmalloc() is called, intialization */
km->base[1] = (size_t)(km->loop_head = q = km->base); *q = 0;