Hi Tony,
On 26/01/2023 18:41, Tony Luck wrote:
> When Sub-NUMA cluster is enabled (snc_ways > 1) use the RDT_RESOURCE_NODE
> instead of RDT_RESOURCE_L3 for all monitoring operations.
>
> The mon_scale and num_rmid values from CPUID(0xf,0x1),(EBX,ECX) must be
> scaled down by the number of Sub-NUMA Clusters.
>
> A subsequent change will detect sub-NUMA cluster mode and set
> "snc_ways". For now set to one (meaning each L3 cache spans one
> node).
(I'm looking at decoupling "monitoring is always on RDT_RESOURCE_L3" as a separate thing
to enabling SNC ... just in case my comments seem strange!)
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index 19be6fe42ef3..53b2ab37af2f 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -786,7 +791,13 @@ static __init bool get_rdt_alloc_resources(void)
>
> static __init bool get_rdt_mon_resources(void)
> {
> - struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> + struct rdt_resource *r;
> +
> + /* When SNC enabled, monitor functions at node instead of L3 cache scope */
> + if (snc_ways > 1)
> + r = &rdt_resources_all[RDT_RESOURCE_NODE].r_resctrl;
> + else
> + r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
Could this be hidden in a helper with some name like resctrl_arch_get_mbm_resource()?
You have the same pattern again in rdt_get_tree(). If this gets more complex in the
future, it means its outside the filesystem code, and all in one place.
Thanks,
James
> if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC))
> rdt_mon_features |= (1 << QOS_L3_OCCUP_EVENT_ID);
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index a6ba3080e5db..a0dc64a70d01 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -2238,7 +2238,10 @@ static int rdt_get_tree(struct fs_context *fc)
> static_branch_enable_cpuslocked(&rdt_enable_key);
>
> if (is_mbm_enabled()) {
> - r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> + if (snc_ways > 1)
> + r = &rdt_resources_all[RDT_RESOURCE_NODE].r_resctrl;
> + else
> + r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
> list_for_each_entry(dom, &r->domains, list)
> mbm_setup_overflow_handler(dom, MBM_OVERFLOW_INTERVAL);
> }
