RE: [Xen-users] SMP and CPU hyperthreading

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

> > There's not much point using the noht flag.  Just pin the 
> domains to 
> > the logical processors you want to use.  If you don't want 
> to use both 
> > threads on a core then just assign domains to one of them.
> 
> Ok, how should the syntax be for using both threads on a cpu.
> 
> cpu = 0,1 ?

The CPU enumeration order is: hyperthreads, cores, sockets, nodes
(though not all levels are currently implementes). i.e. on a 2 socket,
single core, Xeon box:

  cpu 0 : socket 0, [core 0], hyperthread 0
  cpu 1 : socket 0, [core 0], hyperthread 1
  cpu 2 : socket 1, [core 0], hyperthread 0
  cpu 3 : socket 1, [core 0], hyperthread 1

It's sensible to reserve cpu 0 for domain 0, and then put all your other
domains on CPUs 1 and 3 (leave CPU 2 empty, unless you know that you're
not going to thrash the chip's cache).

Ian

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