Re: [PATCH for-6.2 v3 06/11] machine: Prefer cores over sockets in smp parsing since 6.2

[Cornelia Huck]

On Wed, Jul 28 2021, Yanan Wang <wangyanan55@huawei.com> wrote:

> In the real SMP hardware topology world, it's much more likely that
> we have high cores-per-socket counts and few sockets totally. While
> the current preference of sockets over cores in smp parsing results
> in a virtual cpu topology with low cores-per-sockets counts and a
> large number of sockets, which is just contrary to the real world.
>
> Given that it is better to make the virtual cpu topology be more
> reflective of the real world and also for the sake of compatibility,
> we start to prefer cores over sockets over threads in smp parsing
> since machine type 6.2 for different arches.
>
> In this patch, a boolean "smp_prefer_sockets" is added, and we only
> enable the old preference on older machines and enable the new one
> since type 6.2 for all arches by using the machine compat mechanism.
>
> Acked-by: David Gibson <david@gibson.dropbear.id.au>
> Suggested-by: Daniel P. Berrange <berrange@redhat.com>
> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
> ---
>  hw/arm/virt.c              |  1 +
>  hw/core/machine.c          | 36 ++++++++++++++++++++++++++----------
>  hw/i386/pc.c               | 36 ++++++++++++++++++++++++++----------
>  hw/i386/pc_piix.c          |  1 +
>  hw/i386/pc_q35.c           |  1 +
>  hw/ppc/spapr.c             |  1 +
>  hw/s390x/s390-virtio-ccw.c |  1 +
>  include/hw/boards.h        |  1 +
>  qemu-options.hx            |  3 ++-
>  9 files changed, 60 insertions(+), 21 deletions(-)

Acked-by: Cornelia Huck <cohuck@redhat.com>