Re: [PATCH v11 21/31] x86/resctrl: Handle domain creation/deletion for RDT_RESOURCE_PERF_PKG

[Reinette Chatre]

Hi Tony,

(subject prefix missing the resctrl fs changes)

On 9/25/25 1:03 PM, Tony Luck wrote:
> The L3 resource has several requirements for domains. There are per-domain
> structures that hold the 64-bit values of counters, and elements to keep
> track of the overflow and limbo threads.
> 
> None of these are needed for the PERF_PKG resource. The hardware counters
> are wide enough that they do not wrap around for decades.
> 
> Define a new rdt_perf_pkg_mon_domain structure which just consists of
> the standard rdt_domain_hdr to keep track of domain id and CPU mask.
> 
> Support the PERF_PKG resource in the CPU online/offline handlers.

Above can be seen from the patch. Would be helpful to highlight what this
support involves since it is not obvious from changes that just adds 
gotos.

> 
> Add WARN checks to code that sums domains for Sub-NUMA cluster to
> confirm the resource ID is RDT_RESOURCE_L3.

Above is clear from patch. Is there a "why" since it is not clear what
these changes that are related to counter reading have to do with domain
creation and deletion topic of this patch.

> 
> Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
> ---
>  arch/x86/kernel/cpu/resctrl/internal.h  | 13 +++++++++++
>  arch/x86/kernel/cpu/resctrl/core.c      | 15 +++++++++++++
>  arch/x86/kernel/cpu/resctrl/intel_aet.c | 29 +++++++++++++++++++++++++
>  fs/resctrl/ctrlmondata.c                |  5 +++++
>  fs/resctrl/rdtgroup.c                   | 10 +++++++++
>  5 files changed, 72 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 97616c81682b..b920f54f8736 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -84,6 +84,14 @@ static inline struct rdt_hw_l3_mon_domain *resctrl_to_arch_mon_dom(struct rdt_l3
>  	return container_of(r, struct rdt_hw_l3_mon_domain, d_resctrl);
>  }
>  
> +/**
> + * struct rdt_perf_pkg_mon_domain - CPUs sharing an package scoped resctrl monitor resource
> + * @hdr:	common header for different domain types
> + */
> +struct rdt_perf_pkg_mon_domain {
> +	struct rdt_domain_hdr	hdr;
> +};
> +
>  /**
>   * struct msr_param - set a range of MSRs from a domain
>   * @res:       The resource to use
> @@ -222,6 +230,8 @@ bool intel_aet_get_events(void);
>  void __exit intel_aet_exit(void);
>  int intel_aet_read_event(int domid, u32 rmid, enum resctrl_event_id evtid,
>  			 void *arch_priv, u64 *val);
> +void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
> +				struct list_head *add_pos);
>  #else
>  static inline bool intel_aet_get_events(void) { return false; }
>  static inline void __exit intel_aet_exit(void) { }
> @@ -230,6 +240,9 @@ static inline int intel_aet_read_event(int domid, u32 rmid, enum resctrl_event_i
>  {
>  	return -EINVAL;
>  }
> +
> +static inline void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
> +					      struct list_head *add_pos) { }
>  #endif
>  
>  #endif /* _ASM_X86_RESCTRL_INTERNAL_H */
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index 588de539a739..5dff83e763a5 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -573,6 +573,10 @@ static void domain_add_cpu_mon(int cpu, struct rdt_resource *r)
>  		if (!hdr)
>  			l3_mon_domain_setup(cpu, id, r, add_pos);
>  		break;
> +	case RDT_RESOURCE_PERF_PKG:
> +		if (!hdr)
> +			intel_aet_mon_domain_setup(cpu, id, r, add_pos);
> +		break;
>  	default:
>  		pr_warn_once("Unknown resource rid=%d\n", r->rid);
>  		break;
> @@ -635,6 +639,7 @@ static void domain_remove_cpu_ctrl(int cpu, struct rdt_resource *r)
>  static void domain_remove_cpu_mon(int cpu, struct rdt_resource *r)
>  {
>  	int id = get_domain_id_from_scope(cpu, r->mon_scope);
> +	struct rdt_perf_pkg_mon_domain *pkgd;

Please move this declaration to resource specific case statement block.

>  	struct rdt_hw_l3_mon_domain *hw_dom;
>  	struct rdt_l3_mon_domain *d;
>  	struct rdt_domain_hdr *hdr;
> @@ -670,6 +675,16 @@ static void domain_remove_cpu_mon(int cpu, struct rdt_resource *r)
>  		synchronize_rcu();
>  		l3_mon_domain_free(hw_dom);
>  		break;
> +	case RDT_RESOURCE_PERF_PKG:
> +		if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, RDT_RESOURCE_PERF_PKG))
> +			return;
> +
> +		pkgd = container_of(hdr, struct rdt_perf_pkg_mon_domain, hdr);
> +		resctrl_offline_mon_domain(r, hdr);
> +		list_del_rcu(&hdr->list);
> +		synchronize_rcu();
> +		kfree(pkgd);
> +		break;
>  	default:
>  		pr_warn_once("Unknown resource rid=%d\n", r->rid);
>  		break;
> diff --git a/arch/x86/kernel/cpu/resctrl/intel_aet.c b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> index d53211ac6204..dc0d16af66be 100644
> --- a/arch/x86/kernel/cpu/resctrl/intel_aet.c
> +++ b/arch/x86/kernel/cpu/resctrl/intel_aet.c
> @@ -17,16 +17,21 @@
>  #include <linux/compiler_types.h>
>  #include <linux/container_of.h>
>  #include <linux/cpu.h>
> +#include <linux/cpumask.h>
>  #include <linux/err.h>
>  #include <linux/errno.h>
> +#include <linux/gfp_types.h>
>  #include <linux/init.h>
>  #include <linux/intel_pmt_features.h>
>  #include <linux/intel_vsec.h>
>  #include <linux/io.h>
>  #include <linux/overflow.h>
>  #include <linux/printk.h>
> +#include <linux/rculist.h>
> +#include <linux/rcupdate.h>
>  #include <linux/resctrl.h>
>  #include <linux/resctrl_types.h>
> +#include <linux/slab.h>
>  #include <linux/stddef.h>
>  #include <linux/topology.h>
>  #include <linux/types.h>
> @@ -282,3 +287,27 @@ int intel_aet_read_event(int domid, u32 rmid, enum resctrl_event_id eventid,
>  
>  	return valid ? 0 : -EINVAL;
>  }
> +
> +void intel_aet_mon_domain_setup(int cpu, int id, struct rdt_resource *r,
> +				struct list_head *add_pos)
> +{
> +	struct rdt_perf_pkg_mon_domain *d;
> +	int err;
> +
> +	d = kzalloc_node(sizeof(*d), GFP_KERNEL, cpu_to_node(cpu));
> +	if (!d)
> +		return;
> +
> +	d->hdr.id = id;
> +	d->hdr.type = RESCTRL_MON_DOMAIN;
> +	d->hdr.rid = r->rid;

In this series l3_mon_domain_setup() received an update to hardcode the resource. Can this do
the same to be consistent?


Reinette