Re: [RFC PATCH v3 4/4] hw/arm/virt: Parse -smp cluster parameter in virt_smp_parse

[wangyanan (Y)]

Hi Drew,

On 2021/5/17 17:12, Andrew Jones wrote:
> On Sun, May 16, 2021 at 06:32:28PM +0800, Yanan Wang wrote:
> > There is a separate function virt_smp_parse() in hw/virt/arm.c used
> > to parse cpu topology for the ARM machines. So add parsing of -smp
> > cluster parameter in it, then total number of logical cpus will be
> > calculated like: max_cpus = sockets * clusters * cores * threads.
> >
> > Note, we will assume multi-cluster in one socket is not supported
> > and default the value of clusters to 1, if it's not explicitly
> > specified in -smp cmdline.
> >
> > Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
> > ---
> >   hw/arm/virt.c | 32 ++++++++++++++++++--------------
> >   1 file changed, 18 insertions(+), 14 deletions(-)
> >
> > diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> > index 7de822e491..678d5ef36c 100644
> > --- a/hw/arm/virt.c
> > +++ b/hw/arm/virt.c
> > @@ -2642,8 +2642,8 @@ static int virt_kvm_type(MachineState *ms, const char 
> > *type_str)
> >    * with the -smp cmdlines when parsing them.
> >    *
> >    * We require that at least one of cpus or maxcpus must be provided.
> > - * Threads will default to 1 if not provided. Sockets and cores must
> > - * be either both provided or both not.
> > + * Clusters and threads will default to 1 if they are not provided.
> > + * Sockets and cores must be either both provided or both not.
> >    *
> >    * Note, if neither sockets nor cores are specified, we will calculate
> >    * all the missing values just like smp_parse() does, but will disable
> > @@ -2652,15 +2652,18 @@ static int virt_kvm_type(MachineState *ms, const char 
> > *type_str)
> >   static void virt_smp_parse(MachineState *ms, QemuOpts *opts)
> >   {
> >       VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(ms);
> > +    VirtMachineState *vms = VIRT_MACHINE(ms);
> >   
> >       if (opts) {
> >           unsigned cpus = qemu_opt_get_number(opts, "cpus", 0);
> >           unsigned maxcpus = qemu_opt_get_number(opts, "maxcpus", 0);
> >           unsigned sockets = qemu_opt_get_number(opts, "sockets", 0);
> > +        unsigned clusters = qemu_opt_get_number(opts, "clusters", 0);
> >           unsigned cores = qemu_opt_get_number(opts, "cores", 0);
> >           unsigned threads = qemu_opt_get_number(opts, "threads", 0);
> >   
> > -        /* Default threads to 1 if not provided */
> > +        /* Default clusters and threads to 1 if not provided */
> > +        clusters = clusters > 0 ? clusters : 1;
> >           threads = threads > 0 ? threads : 1;
> >   
> >           if (cpus == 0 && maxcpus == 0) {
> > @@ -2676,13 +2679,13 @@ static void virt_smp_parse(MachineState *ms, QemuOpts 
> > *opts)
> >               cores = 1;
> >               if (cpus == 0) {
> >                   sockets = 1;
> > -                cpus = sockets * cores * threads;
> > +                cpus = sockets * clusters * cores * threads;
> >               } else {
> >                   maxcpus = maxcpus > 0 ? maxcpus : cpus;
> > -                sockets = maxcpus / (cores * threads);
> > +                sockets = maxcpus / (clusters * cores * threads);
> >               }
> >           } else if (sockets > 0 && cores > 0) {
> > -            cpus = cpus > 0 ? cpus : sockets * cores * threads;
> > +            cpus = cpus > 0 ? cpus : sockets * clusters * cores * threads;
> >               maxcpus = maxcpus > 0 ? maxcpus : cpus;
> >           } else {
> >               error_report("sockets and cores must be both provided "
> > @@ -2695,25 +2698,26 @@ static void virt_smp_parse(MachineState *ms, QemuOpts 
> > *opts)
> >               exit(1);
> >           }
> >   
> > -        if (sockets * cores * threads < cpus) {
> > +        if (sockets * clusters * cores * threads < cpus) {
> >               error_report("cpu topology: "
> > -                         "sockets (%u) * cores (%u) * threads (%u) < "
> > -                         "smp_cpus (%u)",
> > -                         sockets, cores, threads, cpus);
> > +                         "sockets (%u) * clusters (%u) * cores (%u) * "
> > +                         "threads (%u) < smp_cpus (%u)",
> > +                         sockets, clusters, cores, threads, cpus);
> >               exit(1);
> >           }
> >   
> > -        if (sockets * cores * threads != maxcpus) {
> > +        if (sockets * clusters * cores * threads != maxcpus) {
> >               error_report("cpu topology: "
> > -                         "sockets (%u) * cores (%u) * threads (%u) "
> > -                         "!= maxcpus (%u)",
> > -                         sockets, cores, threads, maxcpus);
> > +                         "sockets (%u) * clusters (%u) * cores (%u) * "
> > +                         "threads (%u) != maxcpus (%u)",
> > +                         sockets, clusters, cores, threads, maxcpus);
> >               exit(1);
> >           }
> >   
> >           ms->smp.cpus = cpus;
> >           ms->smp.max_cpus = maxcpus;
> >           ms->smp.sockets = sockets;
> > +        vms->smp_clusters = clusters;
> >           ms->smp.cores = cores;
> >           ms->smp.threads = threads;
> >       }
> > --
> > 2.19.1
> After reworking "[RFC PATCH v3 9/9] hw/arm/virt: Add separate -smp parsing
> function for ARM machines", this should also be reworked and fully tested,
> possibly using a standalone test, as as I suggested in the other review.
Ok, I will make full test.

Thanks,
Yanan
> Thanks,
> drew
>
> .