From 220f773a0013bf6fe2eefd9718ac7471f368fd8e Mon Sep 17 00:00:00 2001 From: Takuya Yoshikawa Date: Wed, 21 Mar 2012 23:49:39 +0900 Subject: KVM: MMU: Make pte_list_desc fit cache lines well We have PTE_LIST_EXT + 1 pointers in this structure and these 40/20 bytes do not fit cache lines well. Furthermore, some allocators may use 64/32-byte objects for the pte_list_desc cache. This patch solves this problem by changing PTE_LIST_EXT from 4 to 3. For shadow paging, the new size is still large enough to hold both the kernel and process mappings for usual anonymous pages. For file mappings, there may be a slight change in the cache usage. Note: with EPT/NPT we almost always have a single spte in each reverse mapping and we will not see any change by this. Signed-off-by: Takuya Yoshikawa Signed-off-by: Avi Kivity diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index dc5f245..3213348 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -135,8 +135,6 @@ module_param(dbg, bool, 0644); #define PT64_PERM_MASK (PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_USER_MASK \ | PT64_NX_MASK) -#define PTE_LIST_EXT 4 - #define ACC_EXEC_MASK 1 #define ACC_WRITE_MASK PT_WRITABLE_MASK #define ACC_USER_MASK PT_USER_MASK @@ -151,6 +149,9 @@ module_param(dbg, bool, 0644); #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level) +/* make pte_list_desc fit well in cache line */ +#define PTE_LIST_EXT 3 + struct pte_list_desc { u64 *sptes[PTE_LIST_EXT]; struct pte_list_desc *more; -- cgit v0.10.2