我在IBM x3550 M4服务器上的Ubuntu 15.10 x64上的Xen 4.5.1内的PV虚拟机上运行CPU基准测试工具（LINPACK）。该工具应该消耗所有可用的CPU周期。我通过在Xen PV（test.cfg）中定义它来分配4个vCPU。但是，LINPACK只能检测到1个核心和4个线程，而它应该检测至少4个核心：
CPU frequency: 2.494 GHz
Number of CPUs: 1
Number of cores: 1
Number of threads: 4
这就是lscpu在Xen PV VM中所说的内容：
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 4
On-line CPU(s) list: 0-3
Thread(s) per core: 4
Core(s) per socket: 1
Socket(s): 1
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 62
Model name: Intel(R) Xeon(R) CPU E5-2609 v2 @ 2.50GHz
Stepping: 4
CPU MHz: 2500.062
BogoMIPS: 5000.12
Hypervisor vendor: Xen
Virtualization type: full
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 10240K
NUMA node0 CPU(s): 0-3
其他平台（如Docker和HVM DO）在虚拟节点内部分配核心（见下文）。这些节点的性能明显优于Xen PV虚拟节点。
CPU frequency: 2.499 GHz
Number of CPUs: 2
Number of cores: 8
Number of threads: 4
这是DomU Xen主机lscpu：
lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 8
On-line CPU(s) list: 0-7
Thread(s) per core: 1
Core(s) per socket: 4
Socket(s): 2
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 62
Model name: Intel(R) Xeon(R) CPU E5-2609 v2 @ 2.50GHz
Stepping: 4
CPU MHz: 2500.062
BogoMIPS: 5000.12
Hypervisor vendor: Xen
Virtualization type: none
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 10240K
NUMA node0 CPU(s): 0-7
Xen vCPU列表：
xl vcpu-list
Domain-0 0 0 7 -b- 10.1 all / all
Domain-0 0 1 2 -b- 6.5 all / all
Domain-0 0 2 4 r-- 2.6 all / all
Domain-0 0 3 0 r-- 3.9 all / all
Domain-0 0 4 3 -b- 4.4 all / all
Domain-0 0 5 6 -b- 2.6 all / all
Domain-0 0 6 5 -b- 4.7 all / all
Domain-0 0 7 7 -b- 2.9 all / all
test 3 0 1 -b- 1.5 0-3 / all
test 3 1 0 -b- 1.8 0-3 / all
test 3 2 0 -b- 0.7 0-3 / all
test 3 3 2 -b- 0.6 0-3 / all
xen DomU PV VM配置：
cat test.cfg
bootloader = '/usr/lib/xen-4.5/bin/pygrub'
vcpus = '4'
memory = '2048'
cpus = "0-3"
是否有任何选项可以为半虚拟客户端提供host-cpu拓扑？换句话说，如何让Xen使用更多vCPU核心/ vCPU？
谢谢！