linux-kernel - Re: [PATCH v2] x86,sched: allow topologies where NUMA nodes share an LLC

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Date:   Thu, 22 Mar 2018 17:42:41 -0700
From:   Tim Chen <tim.c.chen@...ux.intel.com>
To:     Alison Schofield <alison.schofield@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Luck@...son-desk.jf.intel.com, Tony <tony.luck@...el.com>,
        "H. Peter Anvin" <hpa@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        David Rientjes <rientjes@...gle.com>,
        Igor Mammedov <imammedo@...hat.com>,
        Prarit Bhargava <prarit@...hat.com>, brice.goglin@...il.com,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] x86,sched: allow topologies where NUMA nodes share an
 LLC

On 03/22/2018 01:49 PM, Alison Schofield wrote:
>
> +	 */
> +	if (!topology_same_node(c, o) &&
> +	    (c->x86_vendor == X86_VENDOR_INTEL &&
> +	     c->x86_model == INTEL_FAM6_SKYLAKE_X)) {
> +		/* Use NUMA instead of coregroups for scheduling: */
> +		x86_has_numa_in_package = true;

x86_has_numa_in_package will only be set true for SKYLAKE in the above? 

This boolean probably should be set for (!topology_same_node(c, o) && match_die(c, o)) and not
dependent on cpu family.  Only the return value should depend on cpu family.

Tim


> +
> +		/*
> +		 * Return value doesn't actually matter because we
> +		 * are throwing away coregroups for scheduling anyway.
> +		 * Return false to bypass topology broken bug messages
> +		 * and fixups in sched_domain().
> +		 */
> +		return false;
> +	}
> +
> +	return topology_sane(c, o, "llc");
>  }
>  
>  /*
> @@ -454,12 +492,6 @@ static struct sched_domain_topology_level x86_topology[] = {
>  	{ NULL, },
>  };
>  
> -/*
> - * Set if a package/die has multiple NUMA nodes inside.
> - * AMD Magny-Cours and Intel Cluster-on-Die have this.
> - */
> -static bool x86_has_numa_in_package;
> -
>  void set_cpu_sibling_map(int cpu)
>  {
>  	bool has_smt = smp_num_siblings > 1;
>