From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id CC4591A045E for ; Thu, 3 Mar 2016 12:59:52 +1100 (AEDT) From: David Gibson To: paulus@samba.org, aik@ozlabs.ru, benh@kernel.crashing.org Cc: bharata@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, David Gibson Subject: [RFC 04/18] powerpc/mm: Split hash page table sizing heuristic into a helper Date: Thu, 3 Mar 2016 12:59:35 +1100 Message-Id: <1456970389-28802-5-git-send-email-david@gibson.dropbear.id.au> In-Reply-To: <1456970389-28802-1-git-send-email-david@gibson.dropbear.id.au> References: <1456970389-28802-1-git-send-email-david@gibson.dropbear.id.au> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 --- arch/powerpc/include/asm/mmu-hash64.h | 3 +++ arch/powerpc/mm/hash_utils_64.c | 32 +++++++++++++++++++------------- 2 files changed, 22 insertions(+), 13 deletions(-) diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h index 7352d3f..cf070fd 100644 --- a/arch/powerpc/include/asm/mmu-hash64.h +++ b/arch/powerpc/include/asm/mmu-hash64.h @@ -607,6 +607,9 @@ 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 fdcf9d1..da5d279 100644 --- a/arch/powerpc/mm/hash_utils_64.c +++ b/arch/powerpc/mm/hash_utils_64.c @@ -611,10 +611,26 @@ 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 / 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 @@ -624,17 +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 -- 2.5.0