Re: Domain-0 CPU pinning - is it still a best practice?

[Brian Blood <brian@xxxxxxxxxxxx>]

> for xl). Are people still dedicating CPU cores to dom0 in modern
> versions of Xen with credit2 scheduler?
> 
> If I put this on the hypervisor command line:
> 
>    dom0_max_vcpus=2 dom0_vcpus_pin
> 
> how do I know which PCPUs dom0 will be pinned to?


I do this, but then I take it a little bit further, especially with NUMA hosts.


Let’s suppose I have a dual-socket 8-core CPU machine with HT enabled. 32 
logical CPUs, right?

I use those hypervisor command line configs and some commands in rc.local to 
end up with the following:


# xl cpupool-list
Name               CPUs   Sched     Active   Domain count
Pool-dom0            4    credit       y          1
Pool-CPU1           12    credit       y          5
Pool-CPU2           16    credit       y          3


dom0 ends up being assigned the first 2 physical cores on the first CPU (4 
logicals)

I then have cpu pools for the remainder of the first cpu and then the whole 
entire second CPU.

This gives me plenty of dedicated horsepower for handling IO and s/w RAID ops.

xl cpupool-numa-split
xl cpupool-rename Pool-0 Pool-dom0;

xl cpupool-cpu-remove Pool-dom0 4
xl cpupool-cpu-remove Pool-dom0 5
.
.
.

xl cpupool-create name=\"Pool-CPU1\" 
cpus=["4","5","6","7","8","9","10","11","12","13","14","15"]
xl cpupool-create name=\"Pool-CPU2\" 
cpus=["16","17","18","19","20","21","22","23","24","25","26","27","28","29","30","31"]


—
Brian