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Re: [Qemu-ppc] [PATCH qemu] sysemu: support up to 1024 vCPUs
From: |
David Gibson |
Subject: |
Re: [Qemu-ppc] [PATCH qemu] sysemu: support up to 1024 vCPUs |
Date: |
Fri, 24 Feb 2017 17:16:12 +1100 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
On Fri, Feb 24, 2017 at 03:55:31PM +1100, Alexey Kardashevskiy wrote:
> From: Greg Kurz <address@hidden>
>
> Some systems can already provide more than 255 hardware threads.
>
> Bumping the QEMU limit to 1024 seems reasonable:
> - it has no visible overhead in top;
> - the limit itself has no effect on hot paths.
>
> Cc: Greg Kurz <address@hidden>
> Signed-off-by: Alexey Kardashevskiy <address@hidden>
> ---
>
> With ulimit -u/-n bumped (nproc and nofile), I was able to boot a guest
> with 1024 CPUs, both with threads=1 and threads=8.
>
> It takes time though - 3:15 to get to the guest shell but it is probably
> expected on 160-threads machine.
Applied, thanks.
>
> ---
> 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 e465d7ac98..46b81a625d 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2712,7 +2712,7 @@ static void spapr_machine_class_init(ObjectClass *oc,
> void *data)
> mc->init = ppc_spapr_init;
> mc->reset = ppc_spapr_reset;
> mc->block_default_type = IF_SCSI;
> - mc->max_cpus = 255;
> + mc->max_cpus = 1024;
> mc->no_parallel = 1;
> mc->default_boot_order = "";
> mc->default_ram_size = 512 * M_BYTE;
--
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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