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[174.93.89.182]) by smtp.gmail.com with ESMTPSA id u7sm5407925qta.75.2021.02.04.14.51.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 04 Feb 2021 14:51:46 -0800 (PST) Date: Thu, 4 Feb 2021 17:51:44 -0500 From: Peter Xu To: Ben Gardon Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Paolo Bonzini , Sean Christopherson , Peter Shier , Junaid Shahid , Jim Mattson , Makarand Sonare , Kai Huang Subject: Re: [PATCH] KVM: VMX: Optimize flushing the PML buffer Message-ID: <20210204225144.GU6468@xz-x1> References: <20210204221959.232582-1-bgardon@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210204221959.232582-1-bgardon@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Ben, On Thu, Feb 04, 2021 at 02:19:59PM -0800, Ben Gardon wrote: > The average time for each run demonstrated a strange bimodal distribution, > with clusters around 2 seconds and 2.5 seconds. This may have been a > result of vCPU migration between NUMA nodes. Have you thought about using numactl or similar technique to verify your idea (force both vcpu threads binding, and memory allocations)? >From the numbers it already shows improvements indeed, but just curious since you raised this up. :) > @@ -5707,13 +5708,18 @@ static void vmx_flush_pml_buffer(struct kvm_vcpu *vcpu) > else > pml_idx++; > > + memslots = kvm_vcpu_memslots(vcpu); > + > pml_buf = page_address(vmx->pml_pg); > for (; pml_idx < PML_ENTITY_NUM; pml_idx++) { > + struct kvm_memory_slot *memslot; > u64 gpa; > > gpa = pml_buf[pml_idx]; > WARN_ON(gpa & (PAGE_SIZE - 1)); > - kvm_vcpu_mark_page_dirty(vcpu, gpa >> PAGE_SHIFT); > + > + memslot = __gfn_to_memslot(memslots, gpa >> PAGE_SHIFT); > + mark_page_dirty_in_slot(vcpu->kvm, memslot, gpa >> PAGE_SHIFT); Since at it: make "gpa >> PAGE_SHIFT" a temp var too? Thanks, -- Peter Xu