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[libvirt] [PATCH v5 2/2] vl:c: make sure that sockets are calculated correctly in '-smp X' case

Igor Mammedov posted 2 patches 7 years, 2 months ago
[libvirt] [PATCH v5 2/2] vl:c: make sure that sockets are calculated correctly in '-smp X' case
Posted by Igor Mammedov 7 years, 2 months ago 
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 triggable
   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 omited on CLI.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
 vl.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/vl.c b/vl.c
index 7fd700e..333d638 100644
--- a/vl.c
+++ b/vl.c
@@ -1210,11 +1210,14 @@ 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 = !sockets ? max_cpus / (cores * threads) : sockets;
             }
         } else if (cores == 0) {
             threads = threads > 0 ? threads : 1;
-- 
2.7.4

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Re: [libvirt] [Qemu-devel] [PATCH v5 2/2] vl:c: make sure that sockets are calculated correctly in '-smp X' case
Posted by Andrew Jones 7 years, 2 months ago 
On Tue, Sep 04, 2018 at 03:22:36PM +0200, Igor Mammedov wrote:
> 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 triggable
>    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 omited on CLI.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
>  vl.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/vl.c b/vl.c
> index 7fd700e..333d638 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1210,11 +1210,14 @@ 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 = !sockets ? max_cpus / (cores * threads) : sockets;
>              }
>          } else if (cores == 0) {
>              threads = threads > 0 ? threads : 1;
> -- 
> 2.7.4
> 
>
 
Reviewed-by: Andrew Jones <drjones@redhat.com>

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Re: [libvirt] [Qemu-devel] [PATCH v5 2/2] vl:c: make sure that sockets are calculated correctly in '-smp X' case
Posted by Eduardo Habkost 7 years, 2 months ago 
On Tue, Sep 04, 2018 at 05:18:48PM +0200, Andrew Jones wrote:
> On Tue, Sep 04, 2018 at 03:22:36PM +0200, Igor Mammedov wrote:
> > 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 triggable
> >    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 omited on CLI.
> > 
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > ---
> >  vl.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/vl.c b/vl.c
> > index 7fd700e..333d638 100644
> > --- a/vl.c
> > +++ b/vl.c
> > @@ -1210,11 +1210,14 @@ 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 = !sockets ? max_cpus / (cores * threads) : sockets;

Why the !sockets check here?  If we have reached this statement
we know that (cpus == 0 || sockets == 0) is true and
(cpus == 0) is false, so sockets is guaranteed to be 0.

Sorry for not spotting this earlier.

> >              }
> >          } else if (cores == 0) {
> >              threads = threads > 0 ? threads : 1;
> > -- 
> > 2.7.4
> > 
> >
>  
> Reviewed-by: Andrew Jones <drjones@redhat.com>

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Re: [libvirt] [Qemu-devel] [PATCH v5 2/2] vl:c: make sure that sockets are calculated correctly in '-smp X' case
Posted by Igor Mammedov 7 years, 2 months ago 
On Tue, 4 Sep 2018 22:40:49 -0300
Eduardo Habkost <ehabkost@redhat.com> wrote:

> On Tue, Sep 04, 2018 at 05:18:48PM +0200, Andrew Jones wrote:
> > On Tue, Sep 04, 2018 at 03:22:36PM +0200, Igor Mammedov wrote:
> > > 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 triggable
> > >    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 omited on CLI.
> > > 
> > > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > > ---
> > >  vl.c | 5 ++++-
> > >  1 file changed, 4 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/vl.c b/vl.c
> > > index 7fd700e..333d638 100644
> > > --- a/vl.c
> > > +++ b/vl.c
> > > @@ -1210,11 +1210,14 @@ 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 = !sockets ? max_cpus / (cores * threads) : sockets;
> 
> Why the !sockets check here?  If we have reached this statement
> we know that (cpus == 0 || sockets == 0) is true and
> (cpus == 0) is false, so sockets is guaranteed to be 0.
Indeed, thanks for spotting it
I'll fix it up and respin

> 
> Sorry for not spotting this earlier.
> 
> > >              }
> > >          } else if (cores == 0) {
> > >              threads = threads > 0 ? threads : 1;
> > > -- 
> > > 2.7.4
> > > 
> > >
> >  
> > Reviewed-by: Andrew Jones <drjones@redhat.com>
> 

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