[Xen-users] Re: [Xen-devel] What's the different for "dom0_max_vcpus=4 dom0_vcpus_pin" and "dom0_max_vcpus=4" ?

[lei yang <yanglei.fage@xxxxxxxxx>]

I want to improve the lmbench results.

can you give me some points to improve it? from kernel userspace glibc gcc view or whatever else.

 

Thanks

Lei

On Sat, May 22, 2010 at 12:09 AM, Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote:

On 21/05/2010 16:55, "Pasi Kärkkäinen" <pasik@xxxxxx> wrote:

>>    if I don't use "xm vcpu-pin" does it will use core 0 1 2 3 by default not
>>    can use 3 4 5 6?
>>
>
> Yes, it'll use 0 1 2 3 as a default. It cannot be changed, unless you do
> custom pinning after the system has started.

It will only stick to 0 1 2 3 if you specify dom0_vcpus_pin on the Xen
command line. And if you do that, then the pinning canno tbe changed by
xm/xl vcpu-pin.

If you do not specify dom0_vcpus_pin then dom0 VCPUs will execute on
arbitrary physical CPUs until you restrict each VCPU's affinity using xm/xl
vcpu-pin.

By default, any VCPU (whether dom0's or a domU's) can be executed at any
time on any physical CPU. If there are CPUs you specifically want to
restrict a given VCPU or domain to, then you have to get busy with xm/xl
vcpu-pin.

Anyway, I think that is this particular horse flogged to death. No more on
xen-devel please.

 K.

-- 
"We learn from failure, not from success!"
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