Could you help me to explain how host cpu handle with cpu ratio? On Thu, Mar 23, 2023, 7:10 PM Sean Mooney <smooney at redhat.com> wrote: > generally you should not > you can use it but the preferd way to do this is use > cpu_shared_set and cpu_dedicated_set (in old releases you would have used > vcpu_pin_set) > > https://docs.openstack.org/nova/latest/configuration/config.html#compute.cpu_shared_set > > https://docs.openstack.org/nova/latest/configuration/config.html#compute.cpu_dedicated_set > > if you dont need cpu pinning just use cpu_share_set to spcify the cores > that can be sued for floatign vms > when you use cpu_shared_set and cpu_dedicated_set any cpu not specified > are reseved for host use. > > https://that.guru/blog/cpu-resources/ and > https://that.guru/blog/cpu-resources-redux/ > > have some useful info but that mostly looking at it form a cpu pinning > angel althoguh the secon one covers cpu_shared_set, > > the issue with usein > > https://docs.openstack.org/nova/latest/configuration/config.html#DEFAULT.reserved_host_cpus > > is that you have to multiple the number of cores that are resverved by the > > https://docs.openstack.org/nova/latest/configuration/config.html#DEFAULT.cpu_allocation_ratio > > which means if you decide to manage that via placement api by using > > https://docs.openstack.org/nova/latest/configuration/config.html#DEFAULT.initial_cpu_allocation_ratio > instead > then you need to update your nova.conf to modify the reservationfi you > change the allocation ratio. > > if instead you use cpu_shared_set and cpu_dedicated_set > you are specifying exactly which cpus nova can use and the allocation > ration nolonger needs to be conisderd. > > in general you shoudl reserve the first core on each cpu socket for the > host os. > if you use hyperthreading then both hyperthread of the first cpu core on > each socket shoudl be omitted > form the cpu_shared_set and cpu_dedicated_set > > > > On Thu, 2023-03-23 at 14:44 +0700, Nguyễn Hữu Khôi wrote: > > Hello guys. > > I am trying google for nova host cpu reserve to prevent host overload > but I > > cannot find any resource about it. Could you give me some information? > > Thanks. > > Nguyen Huu Khoi > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://lists.openstack.org/pipermail/openstack-discuss/attachments/20230323/7ca6545b/attachment.htm>