Re: [Xen-devel] [PATCH 2/2] xen: fill topology info for online cpus only

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Aug 29, 2018 at 08:23:02PM +0200, Juergen Gross wrote:
> The topology information obtainable via XEN_SYSCTL_cputopoinfo is
> filled rather weird: the size of the array is derived from the highest
> online cpu number, while the data is set to "invalid" for not present
> cpus only.
> 
> With smt=0 the information for parked threads is all zero, so it should
> be best to return "invalid" information for offline cpus.
> 
> On a dual core system without this patch xl info -n will print:
> 
> cpu_topology           :
> cpu:    core    socket     node
>   0:       0        0        0
>   1:       0        0        0
>   2:       1        0        0
> 
> while with this patch the output is:
> 
> cpu_topology           :
> cpu:    core    socket     node
>   0:       0        0        0
>   2:       1        0        0
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

I have always wanted to fix this but never got around to it. Thank you!

Reviewed-by: Wei Liu <wei.liu2@xxxxxxxxxx>


> ---
>  xen/common/sysctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
> index 8e83c33a16..6cef6d310b 100644
> --- a/xen/common/sysctl.c
> +++ b/xen/common/sysctl.c
> @@ -358,7 +358,7 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) 
> u_sysctl)
>                  num_cpus = ti->num_cpus;
>              for ( i = 0; i < num_cpus; ++i )
>              {
> -                if ( cpu_present(i) )
> +                if ( cpu_online(i) )
>                  {
>                      cputopo.core = cpu_to_core(i);
>                      cputopo.socket = cpu_to_socket(i);
> -- 
> 2.16.4
> 

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