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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id 19sm4293972wmj.48.2021.08.02.08.25.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 Aug 2021 08:25:13 -0700 (PDT) Subject: Re: [PATCH v3 4/7] KVM: X86: Introduce mmu_rmaps_stat per-vm debugfs file To: Peter Xu , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Vitaly Kuznetsov , Sean Christopherson , Maxim Levitsky References: <20210730220455.26054-1-peterx@redhat.com> <20210730220455.26054-5-peterx@redhat.com> From: Paolo Bonzini Message-ID: <8964c91d-761f-8fd4-e8c6-f85d6e318a45@redhat.com> Date: Mon, 2 Aug 2021 17:25:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210730220455.26054-5-peterx@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 31/07/21 00:04, Peter Xu wrote: > Use this file to dump rmap statistic information. The statistic is done by > calculating the rmap count and the result is log-2-based. > > An example output of this looks like (idle 6GB guest, right after boot linux): > > Rmap_Count: 0 1 2-3 4-7 8-15 16-31 32-63 64-127 128-255 256-511 512-1023 > Level=4K: 3086676 53045 12330 1272 502 121 76 2 0 0 0 > Level=2M: 5947 231 0 0 0 0 0 0 0 0 0 > Level=1G: 32 0 0 0 0 0 0 0 0 0 0 > > Signed-off-by: Peter Xu > --- > arch/x86/kvm/x86.c | 113 +++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 113 insertions(+) This should be in debugfs.c, meaning that the kvm_mmu_slot_lpages() must be in a header. I think mmu.h should do, let me take a look and I can post myself a v4 of these debugfs parts. Paolo > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index e44d8f7781b6..0877340dc6ff 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -30,6 +30,7 @@ > #include "hyperv.h" > #include "lapic.h" > #include "xen.h" > +#include "mmu/mmu_internal.h" > > #include > #include > @@ -59,6 +60,7 @@ > #include > #include > #include > +#include > > #include > > @@ -11193,6 +11195,117 @@ int kvm_arch_post_init_vm(struct kvm *kvm) > return kvm_mmu_post_init_vm(kvm); > } > > +/* > + * This covers statistics <1024 (11=log(1024)+1), which should be enough to > + * cover RMAP_RECYCLE_THRESHOLD. > + */ > +#define RMAP_LOG_SIZE 11 > + > +static const char *kvm_lpage_str[KVM_NR_PAGE_SIZES] = { "4K", "2M", "1G" }; > + > +static int kvm_mmu_rmaps_stat_show(struct seq_file *m, void *v) > +{ > + struct kvm_rmap_head *rmap; > + struct kvm *kvm = m->private; > + struct kvm_memory_slot *slot; > + struct kvm_memslots *slots; > + unsigned int lpage_size, index; > + /* Still small enough to be on the stack */ > + unsigned int *log[KVM_NR_PAGE_SIZES], *cur; > + int i, j, k, l, ret; > + > + memset(log, 0, sizeof(log)); > + > + ret = -ENOMEM; > + for (i = 0; i < KVM_NR_PAGE_SIZES; i++) { > + log[i] = kzalloc(RMAP_LOG_SIZE * sizeof(unsigned int), GFP_KERNEL); > + if (!log[i]) > + goto out; > + } > + > + mutex_lock(&kvm->slots_lock); > + write_lock(&kvm->mmu_lock); > + > + for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { > + slots = __kvm_memslots(kvm, i); > + for (j = 0; j < slots->used_slots; j++) { > + slot = &slots->memslots[j]; > + for (k = 0; k < KVM_NR_PAGE_SIZES; k++) { > + rmap = slot->arch.rmap[k]; > + lpage_size = kvm_mmu_slot_lpages(slot, k + 1); > + cur = log[k]; > + for (l = 0; l < lpage_size; l++) { > + index = ffs(pte_list_count(&rmap[l])); > + if (WARN_ON_ONCE(index >= RMAP_LOG_SIZE)) > + index = RMAP_LOG_SIZE - 1; > + cur[index]++; > + } > + } > + } > + } > + > + write_unlock(&kvm->mmu_lock); > + mutex_unlock(&kvm->slots_lock); > + > + /* index=0 counts no rmap; index=1 counts 1 rmap */ > + seq_printf(m, "Rmap_Count:\t0\t1\t"); > + for (i = 2; i < RMAP_LOG_SIZE; i++) { > + j = 1 << (i - 1); > + k = (1 << i) - 1; > + seq_printf(m, "%d-%d\t", j, k); > + } > + seq_printf(m, "\n"); > + > + for (i = 0; i < KVM_NR_PAGE_SIZES; i++) { > + seq_printf(m, "Level=%s:\t", kvm_lpage_str[i]); > + cur = log[i]; > + for (j = 0; j < RMAP_LOG_SIZE; j++) > + seq_printf(m, "%d\t", cur[j]); > + seq_printf(m, "\n"); > + } > + > + ret = 0; > +out: > + for (i = 0; i < KVM_NR_PAGE_SIZES; i++) > + if (log[i]) > + kfree(log[i]); > + > + return ret; > +} > + > +static int kvm_mmu_rmaps_stat_open(struct inode *inode, struct file *file) > +{ > + struct kvm *kvm = inode->i_private; > + > + if (!kvm_get_kvm_safe(kvm)) > + return -ENOENT; > + > + return single_open(file, kvm_mmu_rmaps_stat_show, kvm); > +} > + > +static int kvm_mmu_rmaps_stat_release(struct inode *inode, struct file *file) > +{ > + struct kvm *kvm = inode->i_private; > + > + kvm_put_kvm(kvm); > + > + return single_release(inode, file); > +} > + > +static const struct file_operations mmu_rmaps_stat_fops = { > + .open = kvm_mmu_rmaps_stat_open, > + .read = seq_read, > + .llseek = seq_lseek, > + .release = kvm_mmu_rmaps_stat_release, > +}; > + > +int kvm_arch_create_vm_debugfs(struct kvm *kvm) > +{ > + debugfs_create_file("mmu_rmaps_stat", 0644, kvm->debugfs_dentry, kvm, > + &mmu_rmaps_stat_fops); > + return 0; > +} > + > static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu) > { > vcpu_load(vcpu); >