KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE is set to 40 without any specific
reason. Reduce default size to PT64_ROOT_MAX_LEVEL, which is currently
5.
Change mmu_pte_list_desc_cache size to what is needed as it is more than
5 but way less than 40.
Tested by running dirty_log_perf_test on both tdp and shadow MMU with 48
vcpu and 2GB/vcpu size on a 2 NUMA node machine. No impact on
performance noticed.
Ran perf on dirty_log_perf_test and found kvm_mmu_get_free_page() calls
reduced by ~3300 which is near to 48 (vcpus) * 2 (nodes) * 35 (cache
size).
Signed-off-by: Vipin Sharma <vipinsh@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_types.h | 2 +-
arch/x86/kvm/mmu/mmu.c | 7 ++++---
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/kvm_types.h b/arch/x86/include/asm/kvm_types.h
index 08f1b57d3b62..752dab218a62 100644
--- a/arch/x86/include/asm/kvm_types.h
+++ b/arch/x86/include/asm/kvm_types.h
@@ -2,6 +2,6 @@
#ifndef _ASM_X86_KVM_TYPES_H
#define _ASM_X86_KVM_TYPES_H
-#define KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE 40
+#define KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE PT64_ROOT_MAX_LEVEL
#endif /* _ASM_X86_KVM_TYPES_H */
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 7454bfc49a51..f89d933ff380 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -677,11 +677,12 @@ static int mmu_topup_sp_memory_cache(struct kvm_mmu_memory_cache *cache,
static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect)
{
- int r, nid;
+ int r, nid, desc_capacity;
/* 1 rmap, 1 parent PTE per level, and the prefetched rmaps. */
- r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache,
- 1 + PT64_ROOT_MAX_LEVEL + PTE_PREFETCH_NUM);
+ desc_capacity = 1 + PT64_ROOT_MAX_LEVEL + PTE_PREFETCH_NUM;
+ r = __kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache,
+ desc_capacity, desc_capacity);
if (r)
return r;
--
2.39.0.314.g84b9a713c41-goog
