Re: [Xen-ia64-devel] vcpu-pin bug to dom0 ?

[Masaki Kanno <kanno.masaki@xxxxxxxxxxxxxx>]

Hi Yongkang,

>Hi all,
>
>I find a strange issue that if I only assign 1 or 2 vcpus to dom0, I can 
>not use vcpu-pin to pin the No. 0 vcpu. It will report: "Invalid argument".
> But it works, if I let Xen0 see all vcpus when booting.
>
>For example, in IA32, set (dom0-cpus 1)
>After Xen0 boot up, "xm vcpu-p 0 0 0" will see errors.
>If setting (dom0-cpus 0), above command works.
>
>In IA64, set dom0_max_vcpus=2 (totally have 16 vcpus)
>After Xen0 boot up, "xm vcpu-p 0 0 0" will see errors.
>But "xm vcpu-p 0 1 0" works.
>

I think that you can solve this problem by applying the following 
patch, and inputting "xm vcpu-pin 0 0 0" from two consoles at the 
same time...  Need many retry :-)

diff -r 5b9ff5e8653a xen/common/domctl.c
--- a/xen/common/domctl.c       Sun Aug 27 06:56:01 2006 +0100
+++ b/xen/common/domctl.c       Mon Aug 28 18:01:28 2006 +0900
@@ -380,13 +380,6 @@ long do_domctl(XEN_GUEST_HANDLE(xen_domc
 
         if ( op->cmd == XEN_DOMCTL_setvcpuaffinity )
         {
-            if ( v == current )
-            {
-                ret = -EINVAL;
-                put_domain(d);
-                break;
-            }
-
             xenctl_cpumap_to_cpumask(
                 &new_affinity, &op->u.vcpuaffinity.cpumap);
             ret = vcpu_set_affinity(v, &new_affinity);


But, if Domain-0 has one virtual CPU, this problem cannot be solved 
even if applying this patch. If you are using CREDIT scheduler, 
'xm vcpu-pin 0 0 0' makes an error by the following line.


static int
csched_vcpu_set_affinity(struct vcpu *vc, cpumask_t *affinity)
{
    unsigned long flags;
    int lcpu;

    if ( vc == current )
    {
        /* No locking needed but also can't move on the spot... */
        if ( !cpu_isset(vc->processor, *affinity) )
            return -EBUSY;   <---- This!

        vc->cpu_affinity = *affinity;
    }


Hi Keir,
Do you have good ideas to solve this problem?


Best regards,
 Kan

>Best Regards,
>Yongkang (Kangkang)
>
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