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Re: [PATCH v3 2/3] xen/sched: Link CPU topology to scheduler
- To: Hirokazu Takahashi <taka@xxxxxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Tue, 30 Jun 2026 09:01:58 +0200
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- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Timothy Pearson <tpearson@xxxxxxxxxxxxxxxxxxxxx>, Alistair Francis <alistair.francis@xxxxxxx>, Connor Davis <connojdavis@xxxxxxxxx>, Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>, Dario Faggioli <dfaggioli@xxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, George Dunlap <gwd@xxxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Tue, 30 Jun 2026 07:02:08 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 29.06.2026 23:58, Hirokazu Takahashi wrote:
> --- a/xen/common/sched/credit2.c
> +++ b/xen/common/sched/credit2.c
> @@ -9,6 +9,7 @@
> * Based on an earlier verson by Emmanuel Ackaouy.
> */
>
> +#include <xen/cpu-topology.h>
> #include <xen/errno.h>
> #include <xen/init.h>
> #include <xen/lib.h>
> @@ -37,6 +38,8 @@ static unsigned int cpu_nr_siblings(unsigned int cpu)
> {
> #ifdef CONFIG_X86
> return cpu_data[cpu].x86_num_siblings;
> +#elif defined(CONFIG_CPU_TOPOLOGY)
> + return cpu_topology ? cpu_topology[cpu].num_siblings : 1;
See my earlier remark regarding the ordering here.
> --- a/xen/common/sysctl.c
> +++ b/xen/common/sysctl.c
> @@ -28,6 +28,7 @@
> #include <xen/pmstat.h>
> #include <xen/livepatch.h>
> #include <xen/coverage.h>
> +#include <xen/cpu-topology.h>
Taking e.g. this #include, ...
> --- a/xen/include/xen/cpu-topology.h
> +++ b/xen/include/xen/cpu-topology.h
> @@ -9,6 +9,10 @@ struct cpu_topology {
> cpumask_var_t thread_sibling;
> cpumask_var_t core_sibling;
> cpumask_var_t cluster_sibling;
> + unsigned int phys_core_id;
> + unsigned int phys_cluster_id;
> + unsigned int phys_socket_id;
> + unsigned int num_siblings;
> };
>
> #ifdef CONFIG_CPU_TOPOLOGY
> @@ -16,11 +20,22 @@ struct cpu_topology {
> extern struct cpu_topology *cpu_topology;
> void init_cpu_topology(void);
>
> +#define cpu_to_core(cpu) (cpu_topology ? cpu_topology[cpu].phys_core_id : 0)
> +#define cpu_to_socket(cpu) (cpu_topology ? cpu_topology[cpu].phys_socket_id
> : 0)
> +
> #else /* CONFIG_CPU_TOPOLOGY */
>
> #define cpu_topology ((struct cpu_topology *)NULL)
> static inline void init_cpu_topology(void) {}
>
> +#ifndef cpu_to_core
> +#define cpu_to_core(cpu) (0)
> +#endif
> +
> +#ifndef cpu_to_socket
> +#define cpu_to_socket(cpu) (0)
> +#endif
... what guarantees, on x86, that cpu_to_core and cpu_to_socket are already
#define-d by this point, so that these fallbacks don't take effect there?
(IOW I think you need to explicitly "#include <asm/processor.h>" below the
#else here. Yet better might be to move those two x86 #define-s to a new
asm/topology.h.)
Jan
|
