From: Takuya Yoshikawa <yoshikawa.takuya@xxxxxxxxxxxxx>
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 <yoshikawa.takuya@xxxxxxxxxxxxx>
---
arch/x86/kvm/mmu.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)
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;
--
1.7.5.4
--
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