From patchwork Tue Jul 6 18:03:47 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jing Zhang X-Patchwork-Id: 1501440 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=kvm-ppc-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20161025 header.b=hHRyc03O; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4GK9RJ5rzHz9shx for ; Wed, 7 Jul 2021 04:03:56 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231165AbhGFSGf (ORCPT ); Tue, 6 Jul 2021 14:06:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51892 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231149AbhGFSGe (ORCPT ); Tue, 6 Jul 2021 14:06:34 -0400 Received: from mail-qk1-x749.google.com (mail-qk1-x749.google.com [IPv6:2607:f8b0:4864:20::749]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0468FC061574 for ; Tue, 6 Jul 2021 11:03:56 -0700 (PDT) Received: by mail-qk1-x749.google.com with SMTP id y5-20020a37af050000b02903a9c3f8b89fso17255525qke.2 for ; Tue, 06 Jul 2021 11:03:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=fF6j8POF8iWLCA43O7ZfDObsMW0wQoLTlF29knN9tKg=; b=hHRyc03OBksoyXSj89AptvKZOBbuf2SKJOosv8ggpviRQetpsOy+KEw+8j+vfumO/R 9MyNqJHkYMvOvVGWUMgdHCpgBK8yr9gBxRn4UVcr3rfKTjMb4NLHzQ8zy4nJK+33X166 IdV39ReiPwMxnsjweT1I9eTRG9RiFTP3OTUpm+5+Q+jN79OA6pkctVb+BHK+E+ACWbhM SknIzUxswsNUUgjGnMIyCEpKP52ldnNYlipLVdjS/2/lJUEu4yO8xkTZBa0bWMxSkY3K 49taI/LuZGDj+gSQqk4qUqq/oeoO29AW9cHM4IMIT/XmVniR6pBDv4hjVgl7jHG3aeQM 0Sug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=fF6j8POF8iWLCA43O7ZfDObsMW0wQoLTlF29knN9tKg=; b=iR9CCT2qymRRrm+wicWCB8rWgayvOFbwkHphsxU1FMnGm12MEx0kXSMbmVKvWIvog/ HrBNN/5/tWcYwZ+hTqV8RjP6KbCh3s7QoiYvgcgHNg5c4z4GxqE5d06piJYbDHb7wU9m mcQXkYn6nU4fze2B15rZr6cvSyFAc6B6DJxQl0YPFmcbZhDq3busaOsmkUFMLk67qaY2 b+Gx3gMbr3yMyEKIWOLUfcX+BxHKv7Q473qKlh8McL9Rz+19jCpuwBlGsW95SEWwQ9C/ 9M5GjL3xZepqO0y7C7B0Y3zbEDlzQxclrY0wFPCQDhDeru5Ju3tQVNFKUCuIy0H8OBvI B2pQ== X-Gm-Message-State: AOAM5319yJn1oO9T2zsaCGvU7sAcJ/YLq7ffFxnCX9JmXvfU1mOoHv7M vVk49nUcNodQSASWY29byw6UR14cMMK7B3fMGA== X-Google-Smtp-Source: ABdhPJzwzjtXd/x2FeBGe16SmcPRnxkwEm8GQ2lTaxo9PvBJj/UVzE1g3b2RBv7jkQA1GUzwRU8OgpCoFkuYFpF3nQ== X-Received: from jgzg.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:1acf]) (user=jingzhangos job=sendgmr) by 2002:a05:6214:8ec:: with SMTP id dr12mr20074756qvb.12.1625594635091; Tue, 06 Jul 2021 11:03:55 -0700 (PDT) Date: Tue, 6 Jul 2021 18:03:47 +0000 In-Reply-To: <20210706180350.2838127-1-jingzhangos@google.com> Message-Id: <20210706180350.2838127-2-jingzhangos@google.com> Mime-Version: 1.0 References: <20210706180350.2838127-1-jingzhangos@google.com> X-Mailer: git-send-email 2.32.0.93.g670b81a890-goog Subject: [PATCH v1 1/4] KVM: stats: Support linear and logarithmic histogram statistics From: Jing Zhang To: KVM , KVMPPC , Paolo Bonzini , Sean Christopherson , Jim Mattson , Peter Shier , Oliver Upton , David Rientjes , David Matlack Cc: Jing Zhang Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org Add new types of KVM stats, linear and logarithmic histogram. Histogram are very useful for observing the value distribution of time or size related stats. Signed-off-by: Jing Zhang Reported-by: kernel test robot Reported-by: kernel test robot --- arch/arm64/kvm/guest.c | 4 --- arch/mips/kvm/mips.c | 4 --- arch/powerpc/kvm/book3s.c | 4 --- arch/powerpc/kvm/booke.c | 4 --- arch/s390/kvm/kvm-s390.c | 4 --- arch/x86/kvm/x86.c | 4 --- include/linux/kvm_host.h | 53 ++++++++++++++++++++++++++++----------- include/linux/kvm_types.h | 16 ++++++++++++ include/uapi/linux/kvm.h | 11 +++++--- virt/kvm/binary_stats.c | 36 ++++++++++++++++++++++++++ 10 files changed, 98 insertions(+), 42 deletions(-) diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c index 1512a8007a78..cb44d8756fa7 100644 --- a/arch/arm64/kvm/guest.c +++ b/arch/arm64/kvm/guest.c @@ -31,8 +31,6 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = { KVM_GENERIC_VM_STATS() }; -static_assert(ARRAY_SIZE(kvm_vm_stats_desc) == - sizeof(struct kvm_vm_stat) / sizeof(u64)); const struct kvm_stats_header kvm_vm_stats_header = { .name_size = KVM_STATS_NAME_SIZE, @@ -52,8 +50,6 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = { STATS_DESC_COUNTER(VCPU, mmio_exit_kernel), STATS_DESC_COUNTER(VCPU, exits) }; -static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) == - sizeof(struct kvm_vcpu_stat) / sizeof(u64)); const struct kvm_stats_header kvm_vcpu_stats_header = { .name_size = KVM_STATS_NAME_SIZE, diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c index af9dd029a4e1..75c6f264c626 100644 --- a/arch/mips/kvm/mips.c +++ b/arch/mips/kvm/mips.c @@ -41,8 +41,6 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = { KVM_GENERIC_VM_STATS() }; -static_assert(ARRAY_SIZE(kvm_vm_stats_desc) == - sizeof(struct kvm_vm_stat) / sizeof(u64)); const struct kvm_stats_header kvm_vm_stats_header = { .name_size = KVM_STATS_NAME_SIZE, @@ -85,8 +83,6 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = { STATS_DESC_COUNTER(VCPU, vz_cpucfg_exits), #endif }; -static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) == - sizeof(struct kvm_vcpu_stat) / sizeof(u64)); const struct kvm_stats_header kvm_vcpu_stats_header = { .name_size = KVM_STATS_NAME_SIZE, diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c index 79833f78d1da..5cc6e90095b0 100644 --- a/arch/powerpc/kvm/book3s.c +++ b/arch/powerpc/kvm/book3s.c @@ -43,8 +43,6 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = { STATS_DESC_ICOUNTER(VM, num_2M_pages), STATS_DESC_ICOUNTER(VM, num_1G_pages) }; -static_assert(ARRAY_SIZE(kvm_vm_stats_desc) == - sizeof(struct kvm_vm_stat) / sizeof(u64)); const struct kvm_stats_header kvm_vm_stats_header = { .name_size = KVM_STATS_NAME_SIZE, @@ -88,8 +86,6 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = { STATS_DESC_COUNTER(VCPU, pthru_host), STATS_DESC_COUNTER(VCPU, pthru_bad_aff) }; -static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) == - sizeof(struct kvm_vcpu_stat) / sizeof(u64)); const struct kvm_stats_header kvm_vcpu_stats_header = { .name_size = KVM_STATS_NAME_SIZE, diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index 551b30d84aee..5ed6c235e059 100644 --- a/arch/powerpc/kvm/booke.c +++ b/arch/powerpc/kvm/booke.c @@ -41,8 +41,6 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = { STATS_DESC_ICOUNTER(VM, num_2M_pages), STATS_DESC_ICOUNTER(VM, num_1G_pages) }; -static_assert(ARRAY_SIZE(kvm_vm_stats_desc) == - sizeof(struct kvm_vm_stat) / sizeof(u64)); const struct kvm_stats_header kvm_vm_stats_header = { .name_size = KVM_STATS_NAME_SIZE, @@ -79,8 +77,6 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = { STATS_DESC_COUNTER(VCPU, pthru_host), STATS_DESC_COUNTER(VCPU, pthru_bad_aff) }; -static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) == - sizeof(struct kvm_vcpu_stat) / sizeof(u64)); const struct kvm_stats_header kvm_vcpu_stats_header = { .name_size = KVM_STATS_NAME_SIZE, diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 1695f0ced5ba..7610d33d319b 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -66,8 +66,6 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = { STATS_DESC_COUNTER(VM, inject_service_signal), STATS_DESC_COUNTER(VM, inject_virtio) }; -static_assert(ARRAY_SIZE(kvm_vm_stats_desc) == - sizeof(struct kvm_vm_stat) / sizeof(u64)); const struct kvm_stats_header kvm_vm_stats_header = { .name_size = KVM_STATS_NAME_SIZE, @@ -174,8 +172,6 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = { STATS_DESC_COUNTER(VCPU, diagnose_other), STATS_DESC_COUNTER(VCPU, pfault_sync) }; -static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) == - sizeof(struct kvm_vcpu_stat) / sizeof(u64)); const struct kvm_stats_header kvm_vcpu_stats_header = { .name_size = KVM_STATS_NAME_SIZE, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8166ad113fb2..b94a80ad5b8d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -239,8 +239,6 @@ const struct _kvm_stats_desc kvm_vm_stats_desc[] = { STATS_DESC_ICOUNTER(VM, nx_lpage_splits), STATS_DESC_PCOUNTER(VM, max_mmu_page_hash_collisions) }; -static_assert(ARRAY_SIZE(kvm_vm_stats_desc) == - sizeof(struct kvm_vm_stat) / sizeof(u64)); const struct kvm_stats_header kvm_vm_stats_header = { .name_size = KVM_STATS_NAME_SIZE, @@ -280,8 +278,6 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = { STATS_DESC_COUNTER(VCPU, directed_yield_successful), STATS_DESC_ICOUNTER(VCPU, guest_mode) }; -static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) == - sizeof(struct kvm_vcpu_stat) / sizeof(u64)); const struct kvm_stats_header kvm_vcpu_stats_header = { .name_size = KVM_STATS_NAME_SIZE, diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index ae7735b490b4..356af173114d 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1273,56 +1273,66 @@ struct _kvm_stats_desc { char name[KVM_STATS_NAME_SIZE]; }; -#define STATS_DESC_COMMON(type, unit, base, exp) \ +#define STATS_DESC_COMMON(type, unit, base, exp, sz, param) \ .flags = type | unit | base | \ BUILD_BUG_ON_ZERO(type & ~KVM_STATS_TYPE_MASK) | \ BUILD_BUG_ON_ZERO(unit & ~KVM_STATS_UNIT_MASK) | \ BUILD_BUG_ON_ZERO(base & ~KVM_STATS_BASE_MASK), \ .exponent = exp, \ - .size = 1 + .size = sz, \ + .hist_param = param -#define VM_GENERIC_STATS_DESC(stat, type, unit, base, exp) \ +#define VM_GENERIC_STATS_DESC(stat, type, unit, base, exp, sz, param) \ { \ { \ - STATS_DESC_COMMON(type, unit, base, exp), \ + STATS_DESC_COMMON(type, unit, base, exp, sz, param), \ .offset = offsetof(struct kvm_vm_stat, generic.stat) \ }, \ .name = #stat, \ } -#define VCPU_GENERIC_STATS_DESC(stat, type, unit, base, exp) \ +#define VCPU_GENERIC_STATS_DESC(stat, type, unit, base, exp, sz, param) \ { \ { \ - STATS_DESC_COMMON(type, unit, base, exp), \ + STATS_DESC_COMMON(type, unit, base, exp, sz, param), \ .offset = offsetof(struct kvm_vcpu_stat, generic.stat) \ }, \ .name = #stat, \ } -#define VM_STATS_DESC(stat, type, unit, base, exp) \ +#define VM_STATS_DESC(stat, type, unit, base, exp, sz, param) \ { \ { \ - STATS_DESC_COMMON(type, unit, base, exp), \ + STATS_DESC_COMMON(type, unit, base, exp, sz, param), \ .offset = offsetof(struct kvm_vm_stat, stat) \ }, \ .name = #stat, \ } -#define VCPU_STATS_DESC(stat, type, unit, base, exp) \ +#define VCPU_STATS_DESC(stat, type, unit, base, exp, sz, param) \ { \ { \ - STATS_DESC_COMMON(type, unit, base, exp), \ + STATS_DESC_COMMON(type, unit, base, exp, sz, param), \ .offset = offsetof(struct kvm_vcpu_stat, stat) \ }, \ .name = #stat, \ } /* SCOPE: VM, VM_GENERIC, VCPU, VCPU_GENERIC */ -#define STATS_DESC(SCOPE, stat, type, unit, base, exp) \ - SCOPE##_STATS_DESC(stat, type, unit, base, exp) +#define STATS_DESC(SCOPE, stat, type, unit, base, exp, sz, param) \ + SCOPE##_STATS_DESC(stat, type, unit, base, exp, sz, param) #define STATS_DESC_CUMULATIVE(SCOPE, name, unit, base, exponent) \ - STATS_DESC(SCOPE, name, KVM_STATS_TYPE_CUMULATIVE, unit, base, exponent) + STATS_DESC(SCOPE, name, KVM_STATS_TYPE_CUMULATIVE, \ + unit, base, exponent, 1, 0) #define STATS_DESC_INSTANT(SCOPE, name, unit, base, exponent) \ - STATS_DESC(SCOPE, name, KVM_STATS_TYPE_INSTANT, unit, base, exponent) + STATS_DESC(SCOPE, name, KVM_STATS_TYPE_INSTANT, \ + unit, base, exponent, 1, 0) #define STATS_DESC_PEAK(SCOPE, name, unit, base, exponent) \ - STATS_DESC(SCOPE, name, KVM_STATS_TYPE_PEAK, unit, base, exponent) + STATS_DESC(SCOPE, name, KVM_STATS_TYPE_PEAK, \ + unit, base, exponent, 1, 0) +#define STATS_DESC_LINEAR_HIST(SCOPE, name, unit, base, exponent, sz, param) \ + STATS_DESC(SCOPE, name, KVM_STATS_TYPE_LINEAR_HIST, \ + unit, base, exponent, sz, param) +#define STATS_DESC_LOG_HIST(SCOPE, name, unit, base, exponent, sz, param) \ + STATS_DESC(SCOPE, name, KVM_STATS_TYPE_LOG_HIST, \ + unit, base, exponent, sz, param) /* Cumulative counter, read/write */ #define STATS_DESC_COUNTER(SCOPE, name) \ @@ -1341,6 +1351,14 @@ struct _kvm_stats_desc { #define STATS_DESC_TIME_NSEC(SCOPE, name) \ STATS_DESC_CUMULATIVE(SCOPE, name, KVM_STATS_UNIT_SECONDS, \ KVM_STATS_BASE_POW10, -9) +/* Linear histogram for time in nanosecond */ +#define STATS_DESC_LINHIST_TIME_NSEC(SCOPE, name, sz, bucket_size) \ + STATS_DESC_LINEAR_HIST(SCOPE, name, KVM_STATS_UNIT_SECONDS, \ + KVM_STATS_BASE_POW10, -9, sz, bucket_size) +/* Logarithmic histogram for time in nanosecond */ +#define STATS_DESC_LOGHIST_TIME_NSEC(SCOPE, name, sz) \ + STATS_DESC_LOG_HIST(SCOPE, name, KVM_STATS_UNIT_SECONDS, \ + KVM_STATS_BASE_POW10, -9, sz, LOGHIST_BASE_2) #define KVM_GENERIC_VM_STATS() \ STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush) @@ -1354,10 +1372,15 @@ struct _kvm_stats_desc { STATS_DESC_TIME_NSEC(VCPU_GENERIC, halt_poll_fail_ns) extern struct dentry *kvm_debugfs_dir; + ssize_t kvm_stats_read(char *id, const struct kvm_stats_header *header, const struct _kvm_stats_desc *desc, void *stats, size_t size_stats, char __user *user_buffer, size_t size, loff_t *offset); +void kvm_stats_linear_hist_update(u64 *data, size_t size, + u64 value, size_t bucket_size); +void kvm_stats_log_hist_update(u64 *data, size_t size, u64 value); + extern const struct kvm_stats_header kvm_vm_stats_header; extern const struct _kvm_stats_desc kvm_vm_stats_desc[]; extern const struct kvm_stats_header kvm_vcpu_stats_header; diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h index ed6a985c5680..cc88cd676775 100644 --- a/include/linux/kvm_types.h +++ b/include/linux/kvm_types.h @@ -76,6 +76,22 @@ struct kvm_mmu_memory_cache { }; #endif +/* Constants used for histogram stats */ +#define LINHIST_SIZE_SMALL 10 +#define LINHIST_SIZE_MEDIUM 20 +#define LINHIST_SIZE_LARGE 50 +#define LINHIST_SIZE_XLARGE 100 +#define LINHIST_BUCKET_SIZE_SMALL 10 +#define LINHIST_BUCKET_SIZE_MEDIUM 100 +#define LINHIST_BUCKET_SIZE_LARGE 1000 +#define LINHIST_BUCKET_SIZE_XLARGE 10000 + +#define LOGHIST_SIZE_SMALL 8 +#define LOGHIST_SIZE_MEDIUM 16 +#define LOGHIST_SIZE_LARGE 32 +#define LOGHIST_SIZE_XLARGE 64 +#define LOGHIST_BASE_2 2 + struct kvm_vm_stat_generic { u64 remote_tlb_flush; }; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 68c9e6d8bbda..ff34a471d9ef 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1963,7 +1963,9 @@ struct kvm_stats_header { #define KVM_STATS_TYPE_CUMULATIVE (0x0 << KVM_STATS_TYPE_SHIFT) #define KVM_STATS_TYPE_INSTANT (0x1 << KVM_STATS_TYPE_SHIFT) #define KVM_STATS_TYPE_PEAK (0x2 << KVM_STATS_TYPE_SHIFT) -#define KVM_STATS_TYPE_MAX KVM_STATS_TYPE_PEAK +#define KVM_STATS_TYPE_LINEAR_HIST (0x3 << KVM_STATS_TYPE_SHIFT) +#define KVM_STATS_TYPE_LOG_HIST (0x4 << KVM_STATS_TYPE_SHIFT) +#define KVM_STATS_TYPE_MAX KVM_STATS_TYPE_LOG_HIST #define KVM_STATS_UNIT_SHIFT 4 #define KVM_STATS_UNIT_MASK (0xF << KVM_STATS_UNIT_SHIFT) @@ -1987,7 +1989,10 @@ struct kvm_stats_header { * Every data item is of type __u64. * @offset: The offset of the stats to the start of stat structure in * struture kvm or kvm_vcpu. - * @unused: Unused field for future usage. Always 0 for now. + * @hist_param: A parameter value used for histogram stats. For linear + * histogram stats, it indicates the size of the bucket; + * For logarithmic histogram stats, it indicates the base + * of the logarithm. Only base of 2 is supported. * @name: The name string for the stats. Its size is indicated by the * &kvm_stats_header->name_size. */ @@ -1996,7 +2001,7 @@ struct kvm_stats_desc { __s16 exponent; __u16 size; __u32 offset; - __u32 unused; + __u32 hist_param; char name[]; }; diff --git a/virt/kvm/binary_stats.c b/virt/kvm/binary_stats.c index e609d428811a..6eead6979a7f 100644 --- a/virt/kvm/binary_stats.c +++ b/virt/kvm/binary_stats.c @@ -144,3 +144,39 @@ ssize_t kvm_stats_read(char *id, const struct kvm_stats_header *header, *offset = pos; return len; } + +/** + * kvm_stats_linear_hist_update() - Update bucket value for linear histogram + * statistics data. + * + * @data: start address of the stats data + * @size: the number of bucket of the stats data + * @value: the new value used to update the linear histogram's bucket + * @bucket_size: the size (width) of a bucket + */ +void kvm_stats_linear_hist_update(u64 *data, size_t size, + u64 value, size_t bucket_size) +{ + size_t index = value / bucket_size; + + if (index >= size) + index = size - 1; + ++data[index]; +} + +/** + * kvm_stats_log_hist_update() - Update bucket value for logarithmic histogram + * statistics data. + * + * @data: start address of the stats data + * @size: the number of bucket of the stats data + * @value: the new value used to update the logarithmic histogram's bucket + */ +void kvm_stats_log_hist_update(u64 *data, size_t size, u64 value) +{ + size_t index = fls64(value); + + if (index >= size) + index = size - 1; + ++data[index]; +}