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

From: David Gibson <david@gibson.dropbear.id.au>
To: Eduardo Habkost <ehabkost@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>,
	qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>,
	Alexander Graf <agraf@suse.de>, Rob Herring <robh@kernel.org>,
	libvir-list@redhat.com, Richard Henderson <rth@twiddle.net>,
	Eric Blake <eblake@redhat.com>,
	Igor Mammedov <imammedo@redhat.com>,
	qemu-arm@nongnu.org,
	"Edgar E. Iglesias" <edgar.iglesias@gmail.com>,
	Peter Crosthwaite <crosthwaite.peter@gmail.com>,
	Markus Armbruster <armbru@redhat.com>,
	Artyom Tarasenko <atar4qemu@gmail.com>,
	Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>,
	Michael Walle <michael@walle.cc>,
	Marcel Apfelbaum <marcel.apfelbaum@gmail.com>,
	Aleksandar Markovic <amarkovic@wavecomp.com>,
	Aurelien Jarno <aurelien@aurel32.net>,
	Alistair Francis <alistair@alistair23.me>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	qemu-ppc@nongnu.org,
	Xiao Guangrong <xiaoguangrong.eric@gmail.com>,
	Max Filippov <jcmvbkbc@gmail.com>
Subject: Re: [Qemu-devel] [PULL 03/45] vl:c: make sure that sockets are calculated correctly in '-smp X' case
Date: Tue, 23 Oct 2018 16:06:24 +0100	[thread overview]
Message-ID: <20181023150624.GB12127@umbus.hotspot.internet-for-guests.com> (raw)
In-Reply-To: <20181018200422.4358-4-ehabkost@redhat.com>

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On Thu, Oct 18, 2018 at 05:03:40PM -0300, Eduardo Habkost wrote:
> From: Igor Mammedov <imammedo@redhat.com>
> 
> 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 <imammedo@redhat.com>
> Reviewed-by: Andrew Jones <drjones@redhat.com>
> Message-Id: <1536836762-273036-3-git-send-email-imammedo@redhat.com>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  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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