Re: [Qemu-devel] [PULL 03/45] vl:c: make sure that sockets are calculated correctly in '-smp X' case

[David Gibson]

On Thu, Oct 18, 2018 at 05:03:40PM -0300, Eduardo Habkost wrote:
> From: Igor Mammedov <address@hidden>
> 
> commit
>   (5cdc9b76e3 vl.c: Remove dead assignment)
> removed sockets calculation when 'sockets' weren't provided on CLI
> since there wasn't any users for it back then. Exiting checks
> are neither reachable
>    } else if (sockets * cores * threads < cpus) {
> or nor triggerable
>    if (sockets * cores * threads > max_cpus)
> so we weren't noticing wrong topology since then, since users
> recalculate sockets adhoc on their own.
> 
> However with deprecation check it becomes noticable, for example
>   -smp 2
> will start printing warning:
>   "warning: Invalid CPU topology deprecated: sockets (1) * cores (1) * 
> threads (1) != maxcpus (2)"
> calculating sockets if they weren't specified.
> 
> Fix it by returning back sockets calculation if it's omitted on CLI.
> 
> Signed-off-by: Igor Mammedov <address@hidden>
> Reviewed-by: Andrew Jones <address@hidden>
> Message-Id: <address@hidden>
> Signed-off-by: Eduardo Habkost <address@hidden>

Reviewed-by: David Gibson <address@hidden>

> ---
>  vl.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/vl.c b/vl.c
> index 027d04c7ca..2324321d91 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1199,11 +1199,14 @@ static void smp_parse(QemuOpts *opts)
>  
>          /* compute missing values, prefer sockets over cores over threads */
>          if (cpus == 0 || sockets == 0) {
> -            sockets = sockets > 0 ? sockets : 1;
>              cores = cores > 0 ? cores : 1;
>              threads = threads > 0 ? threads : 1;
>              if (cpus == 0) {
> +                sockets = sockets > 0 ? sockets : 1;
>                  cpus = cores * threads * sockets;
> +            } else {
> +                max_cpus = qemu_opt_get_number(opts, "maxcpus", cpus);
> +                sockets = max_cpus / (cores * threads);
>              }
>          } else if (cores == 0) {
>              threads = threads > 0 ? threads : 1;

-- 
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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