diff options
| author | David Gibson <david@gibson.dropbear.id.au> | 2016-02-09 13:32:43 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2016-03-02 09:06:16 +1100 |
| commit | 5c3c7ede2bdcb85fa2fd51c8147cdf70ebc17fcb (patch) | |
| tree | 53b8530977350f92bf76ac0373eb7023a18839a3 /arch | |
| parent | 1dace6c665ec59bdc4eeafa4db7228c1a673e2e2 (diff) | |
powerpc/mm: Split hash page table sizing heuristic into a helper
htab_get_table_size() either retrieve the size of the hash page table (HPT)
from the device tree - if the HPT size is determined by firmware - or
uses a heuristic to determine a good size based on RAM size if the kernel
is responsible for allocating the HPT.
To support a PAPR extension allowing resizing of the HPT, we're going to
want the memory size -> HPT size logic elsewhere, so split it out into a
helper function.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/include/asm/mmu-hash64.h | 3 | ||||
| -rw-r--r-- | arch/powerpc/mm/hash_utils_64.c | 34 |
2 files changed, 24 insertions, 13 deletions
diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h index e36dc90c80d0..0cea4807e26f 100644 --- a/arch/powerpc/include/asm/mmu-hash64.h +++ b/arch/powerpc/include/asm/mmu-hash64.h @@ -608,6 +608,9 @@ static inline unsigned long get_kernel_vsid(unsigned long ea, int ssize) context = (MAX_USER_CONTEXT) + ((ea >> 60) - 0xc) + 1; return get_vsid(context, ea, ssize); } + +unsigned htab_shift_for_mem_size(unsigned long mem_size); + #endif /* __ASSEMBLY__ */ #endif /* _ASM_POWERPC_MMU_HASH64_H_ */ diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c index 335cd4115646..90dd9280894f 100644 --- a/arch/powerpc/mm/hash_utils_64.c +++ b/arch/powerpc/mm/hash_utils_64.c @@ -609,10 +609,28 @@ static int __init htab_dt_scan_pftsize(unsigned long node, return 0; } -static unsigned long __init htab_get_table_size(void) +unsigned htab_shift_for_mem_size(unsigned long mem_size) { - unsigned long mem_size, rnd_mem_size, pteg_count, psize; + unsigned memshift = __ilog2(mem_size); + unsigned pshift = mmu_psize_defs[mmu_virtual_psize].shift; + unsigned pteg_shift; + + /* round mem_size up to next power of 2 */ + if ((1UL << memshift) < mem_size) + memshift += 1; + + /* aim for 2 pages / pteg */ + pteg_shift = memshift - (pshift + 1); + /* + * 2^11 PTEGS of 128 bytes each, ie. 2^18 bytes is the minimum htab + * size permitted by the architecture. + */ + return max(pteg_shift + 7, 18U); +} + +static unsigned long __init htab_get_table_size(void) +{ /* If hash size isn't already provided by the platform, we try to * retrieve it from the device-tree. If it's not there neither, we * calculate it now based on the total RAM size @@ -622,17 +640,7 @@ static unsigned long __init htab_get_table_size(void) if (ppc64_pft_size) return 1UL << ppc64_pft_size; - /* round mem_size up to next power of 2 */ - mem_size = memblock_phys_mem_size(); - rnd_mem_size = 1UL << __ilog2(mem_size); - if (rnd_mem_size < mem_size) - rnd_mem_size <<= 1; - - /* # pages / 2 */ - psize = mmu_psize_defs[mmu_virtual_psize].shift; - pteg_count = max(rnd_mem_size >> (psize + 1), 1UL << 11); - - return pteg_count << 7; + return 1UL << htab_shift_for_mem_size(memblock_phys_mem_size()); } #ifdef CONFIG_MEMORY_HOTPLUG |