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charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org Hi David, On Wed, May 19, 2021 at 12:02 PM David Matlack wrote: > > On Mon, May 17, 2021 at 9:25 AM Jing Zhang wrote: > > > > Update KVM API documentation for binary statistics. > > > > Signed-off-by: Jing Zhang > > --- > > Documentation/virt/kvm/api.rst | 171 +++++++++++++++++++++++++++++++++ > > 1 file changed, 171 insertions(+) > > > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > > index 7fcb2fd38f42..9a6aa9770dfd 100644 > > --- a/Documentation/virt/kvm/api.rst > > +++ b/Documentation/virt/kvm/api.rst > > @@ -5034,6 +5034,169 @@ see KVM_XEN_VCPU_SET_ATTR above. > > The KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST type may not be used > > with the KVM_XEN_VCPU_GET_ATTR ioctl. > > > > +4.130 KVM_STATS_GETFD > > +--------------------- > > + > > +:Capability: KVM_CAP_STATS_BINARY_FD > > +:Architectures: all > > +:Type: vm ioctl, vcpu ioctl > > +:Parameters: none > > +:Returns: statistics file descriptor on success, < 0 on error > > + > > +Errors: > > + > > + ====== ====================================================== > > + ENOMEM if the fd could not be created due to lack of memory > > + EMFILE if the number of opened files exceeds the limit > > + ====== ====================================================== > > + > > +The file descriptor can be used to read VM/vCPU statistics data in binary > > +format. The file data is organized into three blocks as below: > > ++-------------+ > > +| Header | > > ++-------------+ > > +| Descriptors | > > ++-------------+ > > +| Stats Data | > > ++-------------+ > > + > > +The Header block is always at the start of the file. It is only needed to be > > +read one time after a system boot. > > +It is in the form of ``struct kvm_stats_header`` as below:: > > + > > + #define KVM_STATS_ID_MAXLEN 64 > > + > > + struct kvm_stats_header { > > + char id[KVM_STATS_ID_MAXLEN]; > > + __u32 name_size; > > + __u32 count; > > + __u32 desc_offset; > > + __u32 data_offset; > > + }; > > + > > +The ``id`` field is identification for the corresponding KVM statistics. For > > +KVM statistics, it is in the form of "kvm-{kvm pid}", like "kvm-12345". For > > +VCPU statistics, it is in the form of "kvm-{kvm pid}/vcpu-{vcpu id}", like > > +"kvm-12345/vcpu-12". > > + > > +The ``name_size`` field is the size (byte) of the statistics name string > > +(including trailing '\0') appended to the end of every statistics descriptor. > > + > > +The ``count`` field is the number of statistics. > > + > > +The ``desc_offset`` field is the offset of the Descriptors block from the start > > +of the file indicated by the file descriptor. > > + > > +The ``data_offset`` field is the offset of the Stats Data block from the start > > +of the file indicated by the file descriptor. > > + > > +The Descriptors block is only needed to be read once after a system boot. It is > > +an array of ``struct kvm_stats_desc`` as below:: > > + > > + #define KVM_STATS_TYPE_SHIFT 0 > > + #define KVM_STATS_TYPE_MASK (0xF << KVM_STATS_TYPE_SHIFT) > > + #define KVM_STATS_TYPE_CUMULATIVE (0x0 << KVM_STATS_TYPE_SHIFT) > > + #define KVM_STATS_TYPE_INSTANT (0x1 << KVM_STATS_TYPE_SHIFT) > > + #define KVM_STATS_TYPE_MAX KVM_STATS_TYPE_INSTANT > > + > > + #define KVM_STATS_UNIT_SHIFT 4 > > + #define KVM_STATS_UNIT_MASK (0xF << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_NONE (0x0 << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_BYTES (0x1 << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_SECONDS (0x2 << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_CYCLES (0x3 << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_MAX KVM_STATS_UNIT_CYCLES > > + > > + #define KVM_STATS_SCALE_SHIFT 8 > > + #define KVM_STATS_SCALE_MASK (0xF << KVM_STATS_SCALE_SHIFT) > > + #define KVM_STATS_SCALE_POW10 (0x0 << KVM_STATS_SCALE_SHIFT) > > + #define KVM_STATS_SCALE_POW2 (0x1 << KVM_STATS_SCALE_SHIFT) > > + #define KVM_STATS_SCALE_MAX KVM_STATS_SCALE_POW2 > > + > > + struct kvm_stats_desc { > > + __u32 flags; > > + __s16 exponent; > > + __u16 size; > > + __u32 unused1; > > + __u32 unused2; > > + char name[0]; > > + }; > > + > > +The ``flags`` field contains the type and unit of the statistics data described > > +by this descriptor. The following flags are supported: > > + * ``KVM_STATS_TYPE_CUMULATIVE`` > > + The statistics data is cumulative. The value of data can only be increased. > > + Most of the counters used in KVM are of this type. > > + The corresponding ``count`` filed for this type is always 1. > > + * ``KVM_STATS_TYPE_INSTANT`` > > + The statistics data is instantaneous. Its value can be increased or > > + decreased. This type is usually used as a measurement of some resources, > > + like the number of dirty pages, the number of large pages, etc. > > + The corresponding ``count`` field for this type is always 1. > > + * ``KVM_STATS_UNIT_NONE`` > > + There is no unit for the value of statistics data. This usually means that > > + the value is a simple counter of an event. > > + * ``KVM_STATS_UNIT_BYTES`` > > + It indicates that the statistics data is used to measure memory size, in the > > + unit of Byte, KiByte, MiByte, GiByte, etc. The unit of the data is > > + determined by the ``exponent`` field in the descriptor. The > > + ``KVM_STATS_SCALE_POW2`` flag is valid in this case. The unit of the data is > > + determined by ``pow(2, exponent)``. For example, if value is 10, > > + ``exponent`` is 20, which means the unit of statistics data is MiByte, we > > + can get the statistics data in the unit of Byte by > > + ``value * pow(2, exponent) = 10 * pow(2, 20) = 10 MiByte`` which is > > + 10 * 1024 * 1024 Bytes. > > + * ``KVM_STATS_UNIT_SECONDS`` > > + It indicates that the statistics data is used to measure time/latency, in > > + the unit of nanosecond, microsecond, millisecond and second. The unit of the > > + data is determined by the ``exponent`` field in the descriptor. The > > + ``KVM_STATS_SCALE_POW10`` flag is valid in this case. The unit of the data > > + is determined by ``pow(10, exponent)``. For example, if value is 2000000, > > + ``exponent`` is -6, which means the unit of statistics data is microsecond, > > + we can get the statistics data in the unit of second by > > + ``value * pow(10, exponent) = 2000000 * pow(10, -6) = 2 seconds``. > > + * ``KVM_STATS_UNIT_CYCLES`` > > + It indicates that the statistics data is used to measure CPU clock cycles. > > + The ``KVM_STATS_SCALE_POW10`` flag is valid in this case. For example, if > > + value is 200, ``exponent`` is 4, we can get the number of CPU clock cycles > > + by ``value * pow(10, exponent) = 200 * pow(10, 4) = 2000000``. > > + > > +The ``exponent`` field is the scale of corresponding statistics data. It has two > > +values as follows: > > + * ``KVM_STATS_SCALE_POW10`` > > + The scale is based on power of 10. It is used for measurement of time and > > + CPU clock cycles. > > + * ``KVM_STATS_SCALE_POW2`` > > + The scale is based on power of 2. It is used for measurement of memory size. > > + > > +The ``size`` field is the number of values of this statistics data. It is in the > > +unit of ``unsigned long`` for VCPU or ``__u64`` for VM. > > Note it is the reverse in the implementation. Will fix this. Thanks. > > > + > > +The ``unused1`` and ``unused2`` fields are reserved for future > > +support for other types of statistics data, like log/linear histogram. > > + > > +The ``name`` field points to the name string of the statistics data. The name > > +string starts at the end of ``struct kvm_stats_desc``. > > +The maximum length (including trailing '\0') is indicated by ``name_size`` > > +in ``struct kvm_stats_header``. > > + > > +The Stats Data block contains an array of data values of type ``struct > > +kvm_vm_stats_data`` or ``struct kvm_vcpu_stats_data``. It would be read by > > +user space periodically to pull statistics data. > > +The order of data value in Stats Data block is the same as the order of > > +descriptors in Descriptors block. > > + * Statistics data for VM:: > > + > > + struct kvm_vm_stats_data { > > + unsigned long value[0]; > > + }; > > + > > + * Statistics data for VCPU:: > > + > > + struct kvm_vcpu_stats_data { > > + __u64 value[0]; > > + }; > > + > > 5. The kvm_run structure > > ======================== > > > > @@ -6891,3 +7054,11 @@ This capability is always enabled. > > This capability indicates that the KVM virtual PTP service is > > supported in the host. A VMM can check whether the service is > > available to the guest on migration. > > + > > +8.33 KVM_CAP_STATS_BINARY_FD > > +---------------------------- > > + > > +:Architectures: all > > + > > +This capability indicates the feature that user space can create get a file > > +descriptor for every VM and VCPU to read statistics data in binary format. > > -- > > 2.31.1.751.gd2f1c929bd-goog > > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.5 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_INVALID,DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 77607C43461 for ; Wed, 19 May 2021 19:30:39 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id C252C6135F for ; 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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=PGDO8fbc/TF+sFisRne/2XCCw74JXT4LwjRMRFualWE=; b=XgzzCBlq5TEqg50dJGAvV5WqAXxGFnDcK/vS15yyN+n5TvfRvl2qykNdyAqQeaIG56 Nnur2xRmOVrDIZUh/0Tr0DR/Q0V9UOFO1/VRZzMKqUPVba4Ga2aQ6wyX+phT9pqb78l9 lYrCFRzw87B9Dt/Jwjb7qwuZj7jwME4+Ms3ccrEO1BVUqdxdMxVgJwogLWc08BvVLcAc m8SgSKvisWYKHorO5shMLLeytQ/Gk5mA5PFFCBacAFB1dWaB1leaXeclOSdG9ckKbnBI NOigrjFeFqZPk2l3R/faG6NfDZe2pwBJTxvhxpgIOFgmciRCBIZ54NGPFkFkmZWAxlDN 5FZQ== X-Gm-Message-State: AOAM5322/S9bekQWPG2Zqi9ePwt02X6oYsliPAAgWIOn/FWDbRpFNe4z k3JpPuGUqW+9KvG1hZZ6NXcU8JKxYjW+VlArD0EeGw== X-Google-Smtp-Source: ABdhPJyo8bC6y6UGVRkW7FKBnZdE79ScL53BuoAInE7OdE0IuW8eo+EcgjcmmECo9buX4YKaW5GFnqbkZ5ZQQil/rm0= X-Received: by 2002:a2e:87ce:: with SMTP id v14mr546211ljj.28.1621452632154; Wed, 19 May 2021 12:30:32 -0700 (PDT) MIME-Version: 1.0 References: <20210517145314.157626-1-jingzhangos@google.com> <20210517145314.157626-4-jingzhangos@google.com> In-Reply-To: From: Jing Zhang Date: Wed, 19 May 2021 14:30:20 -0500 Message-ID: Subject: Re: [PATCH v5 3/4] KVM: stats: Add documentation for statistics data binary interface To: David Matlack Cc: KVM , David Hildenbrand , Paul Mackerras , Linuxkselftest , Claudio Imbrenda , Will Deacon , KVMARM , Emanuele Giuseppe Esposito , LinuxS390 , Janosch Frank , Oliver Upton , Marc Zyngier , Huacai Chen , Christian Borntraeger , Aleksandar Markovic , David Rientjes , KVMPPC , Jim Mattson , Thomas Bogendoerfer , Sean Christopherson , Cornelia Huck , Peter Shier , LinuxMIPS , Paolo Bonzini , Vitaly Kuznetsov X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi David, On Wed, May 19, 2021 at 12:02 PM David Matlack wrote: > > On Mon, May 17, 2021 at 9:25 AM Jing Zhang wrote: > > > > Update KVM API documentation for binary statistics. > > > > Signed-off-by: Jing Zhang > > --- > > Documentation/virt/kvm/api.rst | 171 +++++++++++++++++++++++++++++++++ > > 1 file changed, 171 insertions(+) > > > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > > index 7fcb2fd38f42..9a6aa9770dfd 100644 > > --- a/Documentation/virt/kvm/api.rst > > +++ b/Documentation/virt/kvm/api.rst > > @@ -5034,6 +5034,169 @@ see KVM_XEN_VCPU_SET_ATTR above. > > The KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST type may not be used > > with the KVM_XEN_VCPU_GET_ATTR ioctl. > > > > +4.130 KVM_STATS_GETFD > > +--------------------- > > + > > +:Capability: KVM_CAP_STATS_BINARY_FD > > +:Architectures: all > > +:Type: vm ioctl, vcpu ioctl > > +:Parameters: none > > +:Returns: statistics file descriptor on success, < 0 on error > > + > > +Errors: > > + > > + ====== ====================================================== > > + ENOMEM if the fd could not be created due to lack of memory > > + EMFILE if the number of opened files exceeds the limit > > + ====== ====================================================== > > + > > +The file descriptor can be used to read VM/vCPU statistics data in binary > > +format. The file data is organized into three blocks as below: > > ++-------------+ > > +| Header | > > ++-------------+ > > +| Descriptors | > > ++-------------+ > > +| Stats Data | > > ++-------------+ > > + > > +The Header block is always at the start of the file. It is only needed to be > > +read one time after a system boot. > > +It is in the form of ``struct kvm_stats_header`` as below:: > > + > > + #define KVM_STATS_ID_MAXLEN 64 > > + > > + struct kvm_stats_header { > > + char id[KVM_STATS_ID_MAXLEN]; > > + __u32 name_size; > > + __u32 count; > > + __u32 desc_offset; > > + __u32 data_offset; > > + }; > > + > > +The ``id`` field is identification for the corresponding KVM statistics. For > > +KVM statistics, it is in the form of "kvm-{kvm pid}", like "kvm-12345". For > > +VCPU statistics, it is in the form of "kvm-{kvm pid}/vcpu-{vcpu id}", like > > +"kvm-12345/vcpu-12". > > + > > +The ``name_size`` field is the size (byte) of the statistics name string > > +(including trailing '\0') appended to the end of every statistics descriptor. > > + > > +The ``count`` field is the number of statistics. > > + > > +The ``desc_offset`` field is the offset of the Descriptors block from the start > > +of the file indicated by the file descriptor. > > + > > +The ``data_offset`` field is the offset of the Stats Data block from the start > > +of the file indicated by the file descriptor. > > + > > +The Descriptors block is only needed to be read once after a system boot. It is > > +an array of ``struct kvm_stats_desc`` as below:: > > + > > + #define KVM_STATS_TYPE_SHIFT 0 > > + #define KVM_STATS_TYPE_MASK (0xF << KVM_STATS_TYPE_SHIFT) > > + #define KVM_STATS_TYPE_CUMULATIVE (0x0 << KVM_STATS_TYPE_SHIFT) > > + #define KVM_STATS_TYPE_INSTANT (0x1 << KVM_STATS_TYPE_SHIFT) > > + #define KVM_STATS_TYPE_MAX KVM_STATS_TYPE_INSTANT > > + > > + #define KVM_STATS_UNIT_SHIFT 4 > > + #define KVM_STATS_UNIT_MASK (0xF << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_NONE (0x0 << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_BYTES (0x1 << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_SECONDS (0x2 << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_CYCLES (0x3 << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_MAX KVM_STATS_UNIT_CYCLES > > + > > + #define KVM_STATS_SCALE_SHIFT 8 > > + #define KVM_STATS_SCALE_MASK (0xF << KVM_STATS_SCALE_SHIFT) > > + #define KVM_STATS_SCALE_POW10 (0x0 << KVM_STATS_SCALE_SHIFT) > > + #define KVM_STATS_SCALE_POW2 (0x1 << KVM_STATS_SCALE_SHIFT) > > + #define KVM_STATS_SCALE_MAX KVM_STATS_SCALE_POW2 > > + > > + struct kvm_stats_desc { > > + __u32 flags; > > + __s16 exponent; > > + __u16 size; > > + __u32 unused1; > > + __u32 unused2; > > + char name[0]; > > + }; > > + > > +The ``flags`` field contains the type and unit of the statistics data described > > +by this descriptor. The following flags are supported: > > + * ``KVM_STATS_TYPE_CUMULATIVE`` > > + The statistics data is cumulative. The value of data can only be increased. > > + Most of the counters used in KVM are of this type. > > + The corresponding ``count`` filed for this type is always 1. > > + * ``KVM_STATS_TYPE_INSTANT`` > > + The statistics data is instantaneous. Its value can be increased or > > + decreased. This type is usually used as a measurement of some resources, > > + like the number of dirty pages, the number of large pages, etc. > > + The corresponding ``count`` field for this type is always 1. > > + * ``KVM_STATS_UNIT_NONE`` > > + There is no unit for the value of statistics data. This usually means that > > + the value is a simple counter of an event. > > + * ``KVM_STATS_UNIT_BYTES`` > > + It indicates that the statistics data is used to measure memory size, in the > > + unit of Byte, KiByte, MiByte, GiByte, etc. The unit of the data is > > + determined by the ``exponent`` field in the descriptor. The > > + ``KVM_STATS_SCALE_POW2`` flag is valid in this case. The unit of the data is > > + determined by ``pow(2, exponent)``. For example, if value is 10, > > + ``exponent`` is 20, which means the unit of statistics data is MiByte, we > > + can get the statistics data in the unit of Byte by > > + ``value * pow(2, exponent) = 10 * pow(2, 20) = 10 MiByte`` which is > > + 10 * 1024 * 1024 Bytes. > > + * ``KVM_STATS_UNIT_SECONDS`` > > + It indicates that the statistics data is used to measure time/latency, in > > + the unit of nanosecond, microsecond, millisecond and second. The unit of the > > + data is determined by the ``exponent`` field in the descriptor. The > > + ``KVM_STATS_SCALE_POW10`` flag is valid in this case. The unit of the data > > + is determined by ``pow(10, exponent)``. For example, if value is 2000000, > > + ``exponent`` is -6, which means the unit of statistics data is microsecond, > > + we can get the statistics data in the unit of second by > > + ``value * pow(10, exponent) = 2000000 * pow(10, -6) = 2 seconds``. > > + * ``KVM_STATS_UNIT_CYCLES`` > > + It indicates that the statistics data is used to measure CPU clock cycles. > > + The ``KVM_STATS_SCALE_POW10`` flag is valid in this case. For example, if > > + value is 200, ``exponent`` is 4, we can get the number of CPU clock cycles > > + by ``value * pow(10, exponent) = 200 * pow(10, 4) = 2000000``. > > + > > +The ``exponent`` field is the scale of corresponding statistics data. It has two > > +values as follows: > > + * ``KVM_STATS_SCALE_POW10`` > > + The scale is based on power of 10. It is used for measurement of time and > > + CPU clock cycles. > > + * ``KVM_STATS_SCALE_POW2`` > > + The scale is based on power of 2. It is used for measurement of memory size. > > + > > +The ``size`` field is the number of values of this statistics data. It is in the > > +unit of ``unsigned long`` for VCPU or ``__u64`` for VM. > > Note it is the reverse in the implementation. Will fix this. Thanks. > > > + > > +The ``unused1`` and ``unused2`` fields are reserved for future > > +support for other types of statistics data, like log/linear histogram. > > + > > +The ``name`` field points to the name string of the statistics data. The name > > +string starts at the end of ``struct kvm_stats_desc``. > > +The maximum length (including trailing '\0') is indicated by ``name_size`` > > +in ``struct kvm_stats_header``. > > + > > +The Stats Data block contains an array of data values of type ``struct > > +kvm_vm_stats_data`` or ``struct kvm_vcpu_stats_data``. It would be read by > > +user space periodically to pull statistics data. > > +The order of data value in Stats Data block is the same as the order of > > +descriptors in Descriptors block. > > + * Statistics data for VM:: > > + > > + struct kvm_vm_stats_data { > > + unsigned long value[0]; > > + }; > > + > > + * Statistics data for VCPU:: > > + > > + struct kvm_vcpu_stats_data { > > + __u64 value[0]; > > + }; > > + > > 5. The kvm_run structure > > ======================== > > > > @@ -6891,3 +7054,11 @@ This capability is always enabled. > > This capability indicates that the KVM virtual PTP service is > > supported in the host. A VMM can check whether the service is > > available to the guest on migration. > > + > > +8.33 KVM_CAP_STATS_BINARY_FD > > +---------------------------- > > + > > +:Architectures: all > > + > > +This capability indicates the feature that user space can create get a file > > +descriptor for every VM and VCPU to read statistics data in binary format. > > -- > > 2.31.1.751.gd2f1c929bd-goog > > _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jing Zhang Date: Wed, 19 May 2021 19:30:20 +0000 Subject: Re: [PATCH v5 3/4] KVM: stats: Add documentation for statistics data binary interface Message-Id: List-Id: References: <20210517145314.157626-1-jingzhangos@google.com> <20210517145314.157626-4-jingzhangos@google.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: David Matlack Cc: KVM , KVMARM , LinuxMIPS , KVMPPC , LinuxS390 , Linuxkselftest , Paolo Bonzini , Marc Zyngier , James Morse , Julien Thierry , Suzuki K Poulose , Will Deacon , Huacai Chen , Aleksandar Markovic , Thomas Bogendoerfer , Paul Mackerras , Christian Borntraeger , Janosch Frank , David Hildenbrand , Cornelia Huck , Claudio Imbrenda , Sean Christopherson , Vitaly Kuznetsov , Jim Mattson , Peter Shier , Oliver Upton , David Rientjes , Emanuele Giuseppe Esposito Hi David, On Wed, May 19, 2021 at 12:02 PM David Matlack wrote: > > On Mon, May 17, 2021 at 9:25 AM Jing Zhang wrote: > > > > Update KVM API documentation for binary statistics. > > > > Signed-off-by: Jing Zhang > > --- > > Documentation/virt/kvm/api.rst | 171 +++++++++++++++++++++++++++++++++ > > 1 file changed, 171 insertions(+) > > > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > > index 7fcb2fd38f42..9a6aa9770dfd 100644 > > --- a/Documentation/virt/kvm/api.rst > > +++ b/Documentation/virt/kvm/api.rst > > @@ -5034,6 +5034,169 @@ see KVM_XEN_VCPU_SET_ATTR above. > > The KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST type may not be used > > with the KVM_XEN_VCPU_GET_ATTR ioctl. > > > > +4.130 KVM_STATS_GETFD > > +--------------------- > > + > > +:Capability: KVM_CAP_STATS_BINARY_FD > > +:Architectures: all > > +:Type: vm ioctl, vcpu ioctl > > +:Parameters: none > > +:Returns: statistics file descriptor on success, < 0 on error > > + > > +Errors: > > + > > + === =========================== > > + ENOMEM if the fd could not be created due to lack of memory > > + EMFILE if the number of opened files exceeds the limit > > + === =========================== > > + > > +The file descriptor can be used to read VM/vCPU statistics data in binary > > +format. The file data is organized into three blocks as below: > > ++-------------+ > > +| Header | > > ++-------------+ > > +| Descriptors | > > ++-------------+ > > +| Stats Data | > > ++-------------+ > > + > > +The Header block is always at the start of the file. It is only needed to be > > +read one time after a system boot. > > +It is in the form of ``struct kvm_stats_header`` as below:: > > + > > + #define KVM_STATS_ID_MAXLEN 64 > > + > > + struct kvm_stats_header { > > + char id[KVM_STATS_ID_MAXLEN]; > > + __u32 name_size; > > + __u32 count; > > + __u32 desc_offset; > > + __u32 data_offset; > > + }; > > + > > +The ``id`` field is identification for the corresponding KVM statistics. For > > +KVM statistics, it is in the form of "kvm-{kvm pid}", like "kvm-12345". For > > +VCPU statistics, it is in the form of "kvm-{kvm pid}/vcpu-{vcpu id}", like > > +"kvm-12345/vcpu-12". > > + > > +The ``name_size`` field is the size (byte) of the statistics name string > > +(including trailing '\0') appended to the end of every statistics descriptor. > > + > > +The ``count`` field is the number of statistics. > > + > > +The ``desc_offset`` field is the offset of the Descriptors block from the start > > +of the file indicated by the file descriptor. > > + > > +The ``data_offset`` field is the offset of the Stats Data block from the start > > +of the file indicated by the file descriptor. > > + > > +The Descriptors block is only needed to be read once after a system boot. It is > > +an array of ``struct kvm_stats_desc`` as below:: > > + > > + #define KVM_STATS_TYPE_SHIFT 0 > > + #define KVM_STATS_TYPE_MASK (0xF << KVM_STATS_TYPE_SHIFT) > > + #define KVM_STATS_TYPE_CUMULATIVE (0x0 << KVM_STATS_TYPE_SHIFT) > > + #define KVM_STATS_TYPE_INSTANT (0x1 << KVM_STATS_TYPE_SHIFT) > > + #define KVM_STATS_TYPE_MAX KVM_STATS_TYPE_INSTANT > > + > > + #define KVM_STATS_UNIT_SHIFT 4 > > + #define KVM_STATS_UNIT_MASK (0xF << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_NONE (0x0 << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_BYTES (0x1 << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_SECONDS (0x2 << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_CYCLES (0x3 << KVM_STATS_UNIT_SHIFT) > > + #define KVM_STATS_UNIT_MAX KVM_STATS_UNIT_CYCLES > > + > > + #define KVM_STATS_SCALE_SHIFT 8 > > + #define KVM_STATS_SCALE_MASK (0xF << KVM_STATS_SCALE_SHIFT) > > + #define KVM_STATS_SCALE_POW10 (0x0 << KVM_STATS_SCALE_SHIFT) > > + #define KVM_STATS_SCALE_POW2 (0x1 << KVM_STATS_SCALE_SHIFT) > > + #define KVM_STATS_SCALE_MAX KVM_STATS_SCALE_POW2 > > + > > + struct kvm_stats_desc { > > + __u32 flags; > > + __s16 exponent; > > + __u16 size; > > + __u32 unused1; > > + __u32 unused2; > > + char name[0]; > > + }; > > + > > +The ``flags`` field contains the type and unit of the statistics data described > > +by this descriptor. The following flags are supported: > > + * ``KVM_STATS_TYPE_CUMULATIVE`` > > + The statistics data is cumulative. The value of data can only be increased. > > + Most of the counters used in KVM are of this type. > > + The corresponding ``count`` filed for this type is always 1. > > + * ``KVM_STATS_TYPE_INSTANT`` > > + The statistics data is instantaneous. Its value can be increased or > > + decreased. This type is usually used as a measurement of some resources, > > + like the number of dirty pages, the number of large pages, etc. > > + The corresponding ``count`` field for this type is always 1. > > + * ``KVM_STATS_UNIT_NONE`` > > + There is no unit for the value of statistics data. This usually means that > > + the value is a simple counter of an event. > > + * ``KVM_STATS_UNIT_BYTES`` > > + It indicates that the statistics data is used to measure memory size, in the > > + unit of Byte, KiByte, MiByte, GiByte, etc. The unit of the data is > > + determined by the ``exponent`` field in the descriptor. The > > + ``KVM_STATS_SCALE_POW2`` flag is valid in this case. The unit of the data is > > + determined by ``pow(2, exponent)``. For example, if value is 10, > > + ``exponent`` is 20, which means the unit of statistics data is MiByte, we > > + can get the statistics data in the unit of Byte by > > + ``value * pow(2, exponent) = 10 * pow(2, 20) = 10 MiByte`` which is > > + 10 * 1024 * 1024 Bytes. > > + * ``KVM_STATS_UNIT_SECONDS`` > > + It indicates that the statistics data is used to measure time/latency, in > > + the unit of nanosecond, microsecond, millisecond and second. The unit of the > > + data is determined by the ``exponent`` field in the descriptor. The > > + ``KVM_STATS_SCALE_POW10`` flag is valid in this case. The unit of the data > > + is determined by ``pow(10, exponent)``. For example, if value is 2000000, > > + ``exponent`` is -6, which means the unit of statistics data is microsecond, > > + we can get the statistics data in the unit of second by > > + ``value * pow(10, exponent) = 2000000 * pow(10, -6) = 2 seconds``. > > + * ``KVM_STATS_UNIT_CYCLES`` > > + It indicates that the statistics data is used to measure CPU clock cycles. > > + The ``KVM_STATS_SCALE_POW10`` flag is valid in this case. For example, if > > + value is 200, ``exponent`` is 4, we can get the number of CPU clock cycles > > + by ``value * pow(10, exponent) = 200 * pow(10, 4) = 2000000``. > > + > > +The ``exponent`` field is the scale of corresponding statistics data. It has two > > +values as follows: > > + * ``KVM_STATS_SCALE_POW10`` > > + The scale is based on power of 10. It is used for measurement of time and > > + CPU clock cycles. > > + * ``KVM_STATS_SCALE_POW2`` > > + The scale is based on power of 2. It is used for measurement of memory size. > > + > > +The ``size`` field is the number of values of this statistics data. It is in the > > +unit of ``unsigned long`` for VCPU or ``__u64`` for VM. > > Note it is the reverse in the implementation. Will fix this. Thanks. > > > + > > +The ``unused1`` and ``unused2`` fields are reserved for future > > +support for other types of statistics data, like log/linear histogram. > > + > > +The ``name`` field points to the name string of the statistics data. The name > > +string starts at the end of ``struct kvm_stats_desc``. > > +The maximum length (including trailing '\0') is indicated by ``name_size`` > > +in ``struct kvm_stats_header``. > > + > > +The Stats Data block contains an array of data values of type ``struct > > +kvm_vm_stats_data`` or ``struct kvm_vcpu_stats_data``. It would be read by > > +user space periodically to pull statistics data. > > +The order of data value in Stats Data block is the same as the order of > > +descriptors in Descriptors block. > > + * Statistics data for VM:: > > + > > + struct kvm_vm_stats_data { > > + unsigned long value[0]; > > + }; > > + > > + * Statistics data for VCPU:: > > + > > + struct kvm_vcpu_stats_data { > > + __u64 value[0]; > > + }; > > + > > 5. The kvm_run structure > > ============ > > > > @@ -6891,3 +7054,11 @@ This capability is always enabled. > > This capability indicates that the KVM virtual PTP service is > > supported in the host. A VMM can check whether the service is > > available to the guest on migration. > > + > > +8.33 KVM_CAP_STATS_BINARY_FD > > +---------------------------- > > + > > +:Architectures: all > > + > > +This capability indicates the feature that user space can create get a file > > +descriptor for every VM and VCPU to read statistics data in binary format. > > -- > > 2.31.1.751.gd2f1c929bd-goog > >