Trace pte prefetch to see what trouble we meet, if can help us to improve the prefetch
Signed-off-by: Xiao Guangrong <[email protected]> --- arch/x86/kvm/mmu.c | 12 +++++++++++- arch/x86/kvm/mmutrace.h | 26 ++++++++++++++++++++++++++ arch/x86/kvm/paging_tmpl.h | 9 ++++++++- 3 files changed, 45 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 941c86b..0aaa18d 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -91,6 +91,11 @@ module_param(oos_shadow, bool, 0644); #define PTE_PREFETCH_NUM 16 +#define PREFETCH_SUCCESS 0 +#define PREFETCH_ERR_GFN2PFN 1 +#define PREFETCH_ERR_ALLOC_MEM 2 +#define PREFETCH_ERR_READ_GPTE 3 + #define PT_FIRST_AVAIL_BITS_SHIFT 9 #define PT64_SECOND_AVAIL_BITS_SHIFT 52 @@ -2066,11 +2071,16 @@ static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep) pfn = gfn_to_pfn_atomic(vcpu->kvm, gfn); if (is_error_pfn(pfn)) { kvm_release_pfn_clean(pfn); + trace_pte_prefetch(true, PREFETCH_ERR_GFN2PFN); break; } - if (pte_prefetch_topup_memory_cache(vcpu)) + + if (pte_prefetch_topup_memory_cache(vcpu)) { + trace_pte_prefetch(true, PREFETCH_ERR_ALLOC_MEM); break; + } + trace_pte_prefetch(true, PREFETCH_SUCCESS); mmu_set_spte(vcpu, spte, ACC_ALL, ACC_ALL, 0, 0, 1, NULL, sp->role.level, gfn, pfn, true, false); } diff --git a/arch/x86/kvm/mmutrace.h b/arch/x86/kvm/mmutrace.h index 3aab0f0..1c3e84e 100644 --- a/arch/x86/kvm/mmutrace.h +++ b/arch/x86/kvm/mmutrace.h @@ -195,6 +195,32 @@ DEFINE_EVENT(kvm_mmu_page_class, kvm_mmu_prepare_zap_page, TP_ARGS(sp) ); + +#define pte_prefetch_err \ + {PREFETCH_SUCCESS, "SUCCESS" }, \ + {PREFETCH_ERR_GFN2PFN, "ERR_GFN2PFN" }, \ + {PREFETCH_ERR_ALLOC_MEM, "ERR_ALLOC_MEM" }, \ + {PREFETCH_ERR_READ_GPTE, "ERR_READ_GPTE" } + +TRACE_EVENT( + pte_prefetch, + TP_PROTO(bool direct, int err_code), + TP_ARGS(direct, err_code), + + TP_STRUCT__entry( + __field(bool, direct) + __field(int, err_code) + ), + + TP_fast_assign( + __entry->direct = direct; + __entry->err_code = err_code; + ), + + TP_printk("%s %s", __entry->direct ? "direct" : "no-direct", + __print_symbolic(__entry->err_code, pte_prefetch_err)) +); + #endif /* _TRACE_KVMMMU_H */ #undef TRACE_INCLUDE_PATH diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index af4e041..64f2acb 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -331,6 +331,8 @@ static void FNAME(pte_prefetch)(struct kvm_vcpu *vcpu, u64 *sptep) page = gfn_to_page_atomic(vcpu->kvm, sp->gfn); if (is_error_page(page)) { kvm_release_page_clean(page); + trace_pte_prefetch(false, + PREFETCH_ERR_READ_GPTE); break; } table = kmap_atomic(page, KM_USER0); @@ -353,11 +355,16 @@ gfn_mapping: pfn = gfn_to_pfn_atomic(vcpu->kvm, gfn); if (is_error_pfn(pfn)) { kvm_release_pfn_clean(pfn); + trace_pte_prefetch(false, PREFETCH_ERR_GFN2PFN); break; } - if (pte_prefetch_topup_memory_cache(vcpu)) + if (pte_prefetch_topup_memory_cache(vcpu)) { + trace_pte_prefetch(false, PREFETCH_ERR_ALLOC_MEM); break; + } + + trace_pte_prefetch(false, PREFETCH_SUCCESS); mmu_set_spte(vcpu, spte, sp->role.access, pte_access, 0, 0, dirty, NULL, sp->role.level, gfn, pfn, true, false); -- 1.6.1.2 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
