linux-kernel - Re: [PATCH v6 7/8] x86/resctrl: Sub NUMA Cluster detection and enable

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Date:   Fri, 29 Sep 2023 16:32:29 +0200
From:   Peter Newman <peternewman@...gle.com>
To:     Tony Luck <tony.luck@...el.com>
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Jonathan Corbet <corbet@....net>,
        Shuah Khan <skhan@...uxfoundation.org>, x86@...nel.org,
        Shaopeng Tan <tan.shaopeng@...itsu.com>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Babu Moger <babu.moger@....com>,
        Randy Dunlap <rdunlap@...radead.org>,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        patches@...ts.linux.dev
Subject: Re: [PATCH v6 7/8] x86/resctrl: Sub NUMA Cluster detection and enable

Hi Tony,

On Thu, Sep 28, 2023 at 9:14 PM Tony Luck <tony.luck@...el.com> wrote:
> +static __init int snc_get_config(void)
> +{
> +       unsigned long *node_caches;
> +       int mem_only_nodes = 0;
> +       int cpu, node, ret;
> +       int num_l3_caches;
> +
> +       if (!x86_match_cpu(snc_cpu_ids))
> +               return 1;
> +
> +       node_caches = bitmap_zalloc(nr_node_ids, GFP_KERNEL);
> +       if (!node_caches)
> +               return 1;
> +
> +       cpus_read_lock();
> +       for_each_node(node) {
> +               cpu = cpumask_first(cpumask_of_node(node));
> +               if (cpu < nr_cpu_ids)
> +                       set_bit(get_cpu_cacheinfo_id(cpu, 3), node_caches);
> +               else
> +                       mem_only_nodes++;
> +       }
> +       cpus_read_unlock();
> +
> +       num_l3_caches = bitmap_weight(node_caches, nr_node_ids);
> +       if (!num_l3_caches)
> +               return 1;
> +
> +       ret = (nr_node_ids - mem_only_nodes) / num_l3_caches;
> +       kfree(node_caches);

It seems a little peculiar to free node_caches a couple of lines after
you're actually done with it.

> +
> +       if (ret > 1)
> +               rdt_resources_all[RDT_RESOURCE_L3].r_resctrl.mon_scope = RESCTRL_NODE;
> +
> +       return ret;
> +}
> +
>  static __init void rdt_init_res_defs_intel(void)
>  {
>         struct rdt_hw_resource *hw_res;
>         struct rdt_resource *r;
>
> +       snc_nodes_per_l3_cache = snc_get_config();
> +
>         for_each_rdt_resource(r) {
>                 hw_res = resctrl_to_arch_res(r);
>
> --
> 2.41.0
>

Reviewed-by: Peter Newman <peternewman@...gle.com>