Re: [Qemu-devel] [PATCH v3] spapr: set vsmt to MAX(8, smp_threads)

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, Feb 09, 2018 at 09:18:58AM +0100, Laurent Vivier wrote:
> We ignore silently the value of smp_threads when we set
> the default VSMT value, and if smp_threads is greater than VSMT
> kernel is going into trouble later.
> 
> Fixes: 8904e5a750
> ("spapr: Adjust default VSMT value for better migration compatibility")
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>

Applied, thanks.

> ---
> 
> Notes:
>     v3: use MAX(8, smp_threads) and let KVM to return an error
>         if nb_threads is too big
>         update subject to reflect the change
>     
>     v2: display a specific error message when the default VSMT is used
>         fix subject
> 
>  hw/ppc/spapr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 32a876be56..c8a1eefa17 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2310,7 +2310,7 @@ static void spapr_set_vsmt_mode(sPAPRMachineState *spapr, Error **errp)
>           * the value that we'd get with KVM on POWER8, the
>           * overwhelmingly common case in production systems.
>           */
> -        spapr->vsmt = 8;
> +        spapr->vsmt = MAX(8, smp_threads);
>      }
>  
>      /* KVM: If necessary, set the SMT mode: */

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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