From ac70c3a8f0d2c44885e89238350b603d9c80182d Mon Sep 17 00:00:00 2001 From: markj Date: Wed, 26 Aug 2020 14:31:48 +0000 Subject: [PATCH] Use a large kmem arena import size on NUMA systems. This helps minimize internal fragmentation that occurs when 2MB imports are interleaved across NUMA domains. Virtually all KVA allocations on direct map platforms consume more than one page, so the fragmentation manifests as runs of 511 4KB page mappings in the kernel. Reviewed by: alc, kib Tested by: pho Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D26050 --- sys/vm/vm_kern.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/sys/vm/vm_kern.c b/sys/vm/vm_kern.c index 2ddad0a9f23..f9414fea663 100644 --- a/sys/vm/vm_kern.c +++ b/sys/vm/vm_kern.c @@ -128,6 +128,7 @@ SYSCTL_ULONG(_vm, OID_AUTO, max_kernel_address, CTLFLAG_RD, #define KVA_QUANTUM_SHIFT (8 + PAGE_SHIFT) #endif #define KVA_QUANTUM (1 << KVA_QUANTUM_SHIFT) +#define KVA_NUMA_IMPORT_QUANTUM (KVA_QUANTUM * 128) extern void uma_startup2(void); @@ -745,6 +746,7 @@ kva_import_domain(void *arena, vmem_size_t size, int flags, vmem_addr_t *addrp) void kmem_init(vm_offset_t start, vm_offset_t end) { + vm_size_t quantum; int domain; vm_map_init(kernel_map, kernel_pmap, VM_MIN_KERNEL_ADDRESS, end); @@ -773,11 +775,21 @@ kmem_init(vm_offset_t start, vm_offset_t end) #endif vm_map_unlock(kernel_map); + /* + * Use a large import quantum on NUMA systems. This helps minimize + * interleaving of superpages, reducing internal fragmentation within + * the per-domain arenas. + */ + if (vm_ndomains > 1 && PMAP_HAS_DMAP) + quantum = KVA_NUMA_IMPORT_QUANTUM; + else + quantum = KVA_QUANTUM; + /* * Initialize the kernel_arena. This can grow on demand. */ vmem_init(kernel_arena, "kernel arena", 0, 0, PAGE_SIZE, 0, 0); - vmem_set_import(kernel_arena, kva_import, NULL, NULL, KVA_QUANTUM); + vmem_set_import(kernel_arena, kva_import, NULL, NULL, quantum); for (domain = 0; domain < vm_ndomains; domain++) { /* @@ -789,13 +801,15 @@ kmem_init(vm_offset_t start, vm_offset_t end) vm_dom[domain].vmd_kernel_arena = vmem_create( "kernel arena domain", 0, 0, PAGE_SIZE, 0, M_WAITOK); vmem_set_import(vm_dom[domain].vmd_kernel_arena, - kva_import_domain, NULL, kernel_arena, KVA_QUANTUM); + kva_import_domain, NULL, kernel_arena, quantum); /* * In architectures with superpages, maintain separate arenas * for allocations with permissions that differ from the * "standard" read/write permissions used for kernel memory, * so as not to inhibit superpage promotion. + * + * Use the base import quantum since this arena is rarely used. */ #if VM_NRESERVLEVEL > 0 vm_dom[domain].vmd_kernel_rwx_arena = vmem_create( -- 2.45.0