From 982792c782ef337381e982fd2047391886f89693 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Wed, 4 Jun 2014 16:06:32 -0700 Subject: [PATCH] x86, mm: probe memory block size for generic x86 64bit On system with 2TiB ram, current x86_64 have 128M as section size, and one memory_block only include one section. So will have 16400 entries under /sys/devices/system/memory/. Current code try to use block id to find block pointer in /sys for any section, and reuse that block pointer. that finding will take some time even after commit 7c243c7168dc ("mm: speedup in __early_pfn_to_nid") that will skip the search in that case during booting up. So solution could be increase block size just like SGI UV system did. (harded code to 2g). This patch is trying to probe the block size to make it match mmio remap size. for example, Intel Nehalem later system will have memory range [0, TOML), [4g, TOMH]. If the memory hole is 2g and total is 128g, TOM will be 2g, and TOM2 will be 130g. We could use 2g as block size instead of default 128M. That will reduce number of entries in /sys/devices/system/memory/ On system 6TiB system will reduce boot time by 35 seconds. Signed-off-by: Yinghai Lu Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/mm/init_64.c | 34 ++++++++++++++++++++++++++++++---- 1 file changed, 30 insertions(+), 4 deletions(-) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index f35c66c5959a..b92591fa8970 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -1230,17 +1230,43 @@ const char *arch_vma_name(struct vm_area_struct *vma) return NULL; } -#ifdef CONFIG_X86_UV -unsigned long memory_block_size_bytes(void) +static unsigned long probe_memory_block_size(void) { + /* start from 2g */ + unsigned long bz = 1UL<<31; + +#ifdef CONFIG_X86_UV if (is_uv_system()) { printk(KERN_INFO "UV: memory block size 2GB\n"); return 2UL * 1024 * 1024 * 1024; } - return MIN_MEMORY_BLOCK_SIZE; -} #endif + /* less than 64g installed */ + if ((max_pfn << PAGE_SHIFT) < (16UL << 32)) + return MIN_MEMORY_BLOCK_SIZE; + + /* get the tail size */ + while (bz > MIN_MEMORY_BLOCK_SIZE) { + if (!((max_pfn << PAGE_SHIFT) & (bz - 1))) + break; + bz >>= 1; + } + + printk(KERN_DEBUG "memory block size : %ldMB\n", bz >> 20); + + return bz; +} + +static unsigned long memory_block_size_probed; +unsigned long memory_block_size_bytes(void) +{ + if (!memory_block_size_probed) + memory_block_size_probed = probe_memory_block_size(); + + return memory_block_size_probed; +} + #ifdef CONFIG_SPARSEMEM_VMEMMAP /* * Initialise the sparsemem vmemmap using huge-pages at the PMD level. -- GitLab