diff options
Diffstat (limited to 'mm/page_alloc.c')
| -rw-r--r-- | mm/page_alloc.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 34240e2a0583..e0f138a47548 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7180,6 +7180,21 @@ static unsigned long __init arch_reserved_kernel_pages(void) #endif /* + * Adaptive scale is meant to reduce sizes of hash tables on large memory + * machines. As memory size is increased the scale is also increased but at + * slower pace. Starting from ADAPT_SCALE_BASE (64G), every time memory + * quadruples the scale is increased by one, which means the size of hash table + * only doubles, instead of quadrupling as well. + * Because 32-bit systems cannot have large physical memory, where this scaling + * makes sense, it is disabled on such platforms. + */ +#if __BITS_PER_LONG > 32 +#define ADAPT_SCALE_BASE (64ul << 30) +#define ADAPT_SCALE_SHIFT 2 +#define ADAPT_SCALE_NPAGES (ADAPT_SCALE_BASE >> PAGE_SHIFT) +#endif + +/* * allocate a large system hash table from bootmem * - it is assumed that the hash table must contain an exact power-of-2 * quantity of entries @@ -7210,6 +7225,16 @@ void *__init alloc_large_system_hash(const char *tablename, if (PAGE_SHIFT < 20) numentries = round_up(numentries, (1<<20)/PAGE_SIZE); +#if __BITS_PER_LONG > 32 + if (!high_limit) { + unsigned long adapt; + + for (adapt = ADAPT_SCALE_NPAGES; adapt < numentries; + adapt <<= ADAPT_SCALE_SHIFT) + scale++; + } +#endif + /* limit to 1 bucket per 2^scale bytes of low memory */ if (scale > PAGE_SHIFT) numentries >>= (scale - PAGE_SHIFT); |