On Wed, Oct 6, 2021 at 9:43 AM Barry Song <21cnbao@xxxxxxxxx> wrote:
>
> On Wed, Oct 6, 2021 at 5:34 AM Valentin Schneider
> <valentin.schneider@xxxxxxx> wrote:
> >
> > On 24/09/21 20:51, Barry Song wrote:
> > > void update_siblings_masks(unsigned int cpuid)
> > > {
> > > struct cpu_topology *cpu_topo, *cpuid_topo = &cpu_topology[cpuid];
> > > @@ -617,6 +622,11 @@ void update_siblings_masks(unsigned int cpuid)
> > > if (cpuid_topo->package_id != cpu_topo->package_id)
> > > continue;
> > >
> > > + if (cpuid_topo->cluster_id == cpu_topo->cluster_id) {
> > > + cpumask_set_cpu(cpu, &cpuid_topo->cluster_sibling);
> > > + cpumask_set_cpu(cpuid, &cpu_topo->cluster_sibling);
> > > + }
> > > +
> >
> > Hm so without cluster information (e.g. DT system), we have
> > ->cluster_id=-1, we'll essentially copy the package mask into the cluster
> > mask.
> >
> > The exposed cluster mask is still <= package mask which is sensible. Are we
> > fine with that, or do we need/want the mask to be empty in the -1 case? I'm
> > guessing userspace tools should check for either id!=-1 or if the exclusive
> > disjucntion of cluster vs package masks is non-empty.
>
> Hi Valentin,
> Yep, this is a very good question. I'd like change the code to:
> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
> index 7cb31d959f33..fc0836f460fb 100644
> --- a/drivers/base/arch_topology.c
> +++ b/drivers/base/arch_topology.c
> @@ -622,7 +622,8 @@ void update_siblings_masks(unsigned int cpuid)
> if (cpuid_topo->package_id != cpu_topo->package_id)
> continue;
>
> - if (cpuid_topo->cluster_id == cpu_topo->cluster_id) {
> + if (cpuid_topo->cluster_id == cpu_topo->cluster_id &&
> + cpuid_topo->cluster_id != -1) {
> cpumask_set_cpu(cpu, &cpuid_topo->cluster_sibling);
> cpumask_set_cpu(cpuid, &cpu_topo->cluster_sibling);
> }
>
Hi Peter,
Would you like to change this line in your tree? Or do you want me to send
a new patchset with this small change?
> This should be consistent with Tim's patch3/3 for x86 in case
> id is BAD_APICID:
> static bool match_l2c(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
> {
> ...
> /* Do not match if we do not have a valid APICID for cpu: */
> if (per_cpu(cpu_l2c_id, cpu1) == BAD_APICID)
> return false;
> ...
> }
Thanks
Barry
