host capability

 

目前經過ComputeCapabilitiesFilter 是能夠作到cpu 指令集的filter，ComputeCapabilitiesFilter 是經過flavor的extra_spe來傳遞的。

傳遞的形式爲：capabilities:cpu_info:features=ssse3 

實現方式：

1.compute_capabilities_filter.py中首先解析flavor-extra_spec ， 獲得capabilities:cpu_info:features 

                if scope[0] != "capabilities":
                    continue

 2.獲得host_state中的cpu_info:features

(Pdb) pp host_state.cpu_info
u'{"vendor": "Intel", "model": "SandyBridge", "arch": "x86_64", "features": 
["pge", "avx", "clflush", "sep", "syscall", "vme", "dtes64", "msr", "fsgsbase", "xsave", "vmx", 
"erms", "xtpr", "cmov", "smep", "ssse3", "est", "pat", "monitor", "smx", "pbe", 
"lm", "tsc", "nx", "fxsr", "tm", "sse4.1", "pae", "sse4.2", "pclmuldq", "acpi", 
"tsc-deadline", "mmx", "osxsave", "cx8", "mce", "de", "tm2", "ht", "pse", "lahf_lm", 
"popcnt", "mca", "apic", "sse", "f16c", "ds", "pni", "rdtscp", "aes", "sse2", "ss", "ds_cpl", 
"pcid", "fpu", "cx16", "pse36", "mtrr", "pdcm", "rdrand", "x2apic"], 
"topology": {"cores": 2, "cells": 1, "threads": 2, "sockets": 1}}'

pp instance_type
Flavor(created_at=None,deleted=False,deleted_at=None,disabled=False,ephemeral_gb=0,
extra_specs={capabilities:cpu_info:arch='x86_64',capabilities:cpu_info:features='<or> acpi,adx,avx,avx2'},
flavorid='1',id=2,is_public=True,memory_mb=512,name='m1.tiny',projects=<?>,root_gb=1,rxtx_factor=1.0,swap=0,updated_at=None,vcpu_weight=0,vcpus=1)

(Pdb) pp scope
[u'cpu_info', u'features']

(Pdb) pp req
u'<or> acpi,adx,avx,avx2'

3. 最後比較req中cpu的須要是否host_state中的cpu_info:features能知足。

那麼，host_state中的cpu_info:features怎麼得到？

1.resource_tracker.py:  self.compute_node.update_from_virt_driver(resources)

    def update_from_virt_driver(self, resources):
        # NOTE(pmurray): the virt driver provides a dict of values that
        # can be copied into the compute node. The names and representation
        # do not exactly match.
        # TODO(pmurray): the resources dict should be formalized.
        keys = ["vcpus", "memory_mb", "local_gb", "cpu_info",
                "vcpus_used", "memory_mb_used", "local_gb_used",
                "numa_topology", "hypervisor_type",
                "hypervisor_version", "hypervisor_hostname",
                "disk_available_least", "host_ip"]
        for key in keys:
            if key in resources:
                self[key] = resources[key]

2.compute_node 把信息report給 scheduler，filter就獲得了 scheduler的host_state

 

Nova中還有一個object VirtCPUModel, 它是 instance object 的一部分，用來描述guest cpu模型，其詳細說明在：

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Administration_Guide/sect-libvirt-dom-xml-cpu-model-top.html

@base.NovaObjectRegistry.register
class VirtCPUModel(base.NovaObject):
    # Version 1.0: Initial version
    VERSION = '1.0'

    fields = {
        'arch': fields.ArchitectureField(nullable=True),
        'vendor': fields.StringField(nullable=True),
        'topology': fields.ObjectField('VirtCPUTopology',
                                       nullable=True),
        'features': fields.ListOfObjectsField("VirtCPUFeature",
                                              default=[]),
        'mode': fields.CPUModeField(nullable=True),
        'model': fields.StringField(nullable=True),
        'match': fields.CPUMatchField(nullable=True),
    }

 object的填充方式：

        guest.cpu = self._get_guest_cpu_config(
            flavor, image_meta, guest_numa_config.numaconfig,
            instance.numa_topology)

        # Notes(yjiang5): we always sync the instance's vcpu model with
        # the corresponding config file.
        instance.vcpu_model = self._cpu_config_to_vcpu_model(
            guest.cpu, instance.vcpu_model)

 mode/model經過nova.conf來配置

    def _get_guest_cpu_model_config(self):
        mode = CONF.libvirt.cpu_mode
        model = CONF.libvirt.cpu_model

topology 經過flave-extra_spec/ image meta 

virt.hardware.py 

def _get_cpu_topology_constraints(flavor, image_meta):
    """Get the topology constraints declared in flavor or image

    :param flavor: Flavor object to read extra specs from
    :param image_meta: nova.objects.ImageMeta object instance

    Gets the topology constraints from the configuration defined
    in the flavor extra specs or the image metadata. In the flavor
    this will look for

     hw:cpu_sockets - preferred socket count
     hw:cpu_cores - preferred core count
     hw:cpu_threads - preferred thread count
     hw:cpu_max_sockets - maximum socket count
     hw:cpu_max_cores - maximum core count
     hw:cpu_max_threads - maximum thread count

    In the image metadata this will look at

     hw_cpu_sockets - preferred socket count
     hw_cpu_cores - preferred core count
     hw_cpu_threads - preferred thread count
     hw_cpu_max_sockets - maximum socket count
     hw_cpu_max_cores - maximum core count
     hw_cpu_max_threads - maximum thread count

 

feature 也是經過flave-extra_spec/ image meta:

class VirtCPUFeature(base.NovaObject):
    VERSION = '1.0'

    fields = {
        'policy': fields.CPUFeaturePolicyField(nullable=True),
        'name': fields.StringField(nullable=False),
    }

        features = [objects.VirtCPUFeature(
            name=f.name,
            policy=f.policy) for f in cpu_config.features]
        vcpu_model.features = features

virt.hardware.py

def _add_cpu_pinning_constraint(flavor, image_meta, numa_topology):
    flavor_pinning = flavor.get('extra_specs', {}).get("hw:cpu_policy")
    image_pinning = image_meta.properties.get("hw_cpu_policy")

 實現了cpu instruction 規則force/require/optional/disable/forbid。

 

經過image來限定有2種：

ImagePropertiesFilter

根據instance's image上定義的屬性來過濾，熟悉包括

architecture, hypervisor type, hypervisor version (for Xen hypervisor type only), and virtual machine mode。

其中，他們的值能夠爲：

arch:
ALL = [
    ALPHA,
    ARMV6,
    ARMV7,
    ARMV7B,

    AARCH64,
    CRIS,
    I686,
    IA64,
    LM32,

    M68K,
    MICROBLAZE,
    MICROBLAZEEL,
    MIPS,
    MIPSEL,

    MIPS64,
    MIPS64EL,
    OPENRISC,
    PARISC,
    PARISC64,

    PPC,
    PPCLE,
    PPC64,
    PPC64LE,
    PPCEMB,

    S390,
    S390X,
    SH4,
    SH4EB,
    SPARC,

    SPARC64,
    UNICORE32,
    X86_64,
    XTENSA,
    XTENSAEB,
]


HVType:
ALL = (
    BAREMETAL,
    BHYVE,
    DOCKER,
    FAKE,
    HYPERV,
    IRONIC,
    KQEMU,
    KVM,
    LXC,
    LXD,
    OPENVZ,
    PARALLELS,
    PHYP,
    QEMU,
    TEST,
    UML,
    VBOX,
    VIRTUOZZO,
    VMWARE,
    XEN,
    ZVM,
)

VMMode:
ALL = [HVM, XEN, UML, EXE]

若是image->properties中沒有這些屬性，則經過過濾；若是有這些屬性，而host->capabilities->supportedinstances沒有，返回False。

好比，

$ glance image-update img-uuid --property architecture=arm --property hypervisor_type=qemu

 

 

2     AggregateImagePropertiesIsolation: 
匹配屬性定義在 image的元數據中,用於對這些 aggregate 組進行匹配

 

好比下面這個 aggregate 分組 myWinAgg 將 windows 系統做爲元數據 os=windows

$ nova aggregate-details MyWinAgg +----+----------+-------------------+------------+---------------+ | Id | Name | Availability Zone | Hosts | Metadata | +----+----------+-------------------+------------+---------------+ | 1 | MyWinAgg | None | 'sf-devel' | 'os=windows' | +----+----------+-------------------+------------+---------------+ 

在這個理子中,由於下面 win-2012的鏡像中有 windows 的屬性, 經過他啓動的虛擬機實例會再 sf-devel 分組上啓動.

$ glance image-show Win-2012 +------------------+--------------------------------------+ | Property | Value | +------------------+--------------------------------------+ | Property 'os' | windows | | checksum | f8a2eeee2dc65b3d9b6e63678955bd83 | | container_format | ami | | created_at | 2013-11-14T13:24:25 |

目前社區關於這塊的工做：

https://review.openstack.org/#/c/286520/3/specs/newton/approved/expose-host-capabilities.rst

打算擴展和統一host capability，主要在現有的host capability之上擴展如下3個方面：

1. 版本capability
2. 用在image filter的architecture, hypervisor type, VM mode
3. 不易被發現的e.g.: SSD, SR-IOV, fibre channel, etc。

 

https://review.openstack.org/#/c/309762/2/specs/newton/approved/standardize-capabilities.rst

試圖採用枚舉的方式(nova.objects.fields.Enum-based)來同一capability的描述模型。

它首先定義了capabilities：

A capability is a *singular* piece of information describing some **functionality** or **feature** of an entity that can be provided to a custom。

好比：

* `hw:x86_cpu_instruction_set_ext:sse`

* `hw:x86_cpu_instruction_set_ext:mmx`

用來表述CPU的指令集

 

* `virt:libvirt:set_admin_pass`

* `virt:libvirt:huge_pages`

* `virt:libvirt:uefi_boot`

用來表述libvirt的capability.