OpenStack调优-设置CPU和内存超售比例

实验环境：openstack 4.0.1

说明：
在OpenStack中，默认的CPU超配比例是1:16，内存超配比例是1:1.5。当宿主机使用swap交换分区来为虚拟机分配内存的时候，则虚拟机的性能将急速下降。生产环境上不建议开启内存超售（建议配置比例1:1）。另外，建议设置nova.conf文件中的reserved_host_memory_mb 参数，即内存预留量（建议至少预留4GB），保证该部分内存不能被虚拟机使用

示例：

[root@controller ~]# vi /etc/nova/nova.conf  //修改nova配置文件

# memory from being considered as available, this option is used to reserve
# memory for the host. For more information, refer to the documentation.
# (integer value)
# Minimum value: 0
reserved_host_memory_mb=4096  //修改内存预留4G即4096

#
# Virtual CPU to physical CPU allocation ratio. For more information, refer to
# the documentation. (floating point value)
# Minimum value: 0
cpu_allocation_ratio=16  //修改cpu超售比例为1:16

#
# Virtual RAM to physical RAM allocation ratio. For more information, refer to
# the documentation. (floating point value)
# Minimum value: 0
ram_allocation_ratio=1.5  //修改ram超售比例为1:1.5

[root@controller ~]# systemctl restart openstack-nova*  //重启nova服务