linux-kernel - Re: [PATCH v3 1/2] perf bench numa: use numa_node_to

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Date:   Thu, 13 Aug 2020 17:37:38 +0530
From:   Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:     Alexander Gordeev <agordeev@...ux.ibm.com>
Cc:     Namhyung Kim <namhyung@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Satheesh Rajendran <sathnaga@...ux.vnet.ibm.com>,
        "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Balamuruhan S <bala24@...ux.vnet.ibm.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH v3 1/2] perf bench numa: use numa_node_to_cpus() to bind
 tasks to nodes

* Alexander Gordeev <agordeev@...ux.ibm.com> [2020-08-13 13:32:48]:

> It is currently assumed that each node contains at most
> nr_cpus/nr_nodes CPUs and nodes' CPU ranges do not overlap.
> That assumption is generally incorrect as there are archs
> where a CPU number does not depend on to its node number.
> 
> This update removes the described assumption by simply calling
> numa_node_to_cpus() interface and using the returned mask for
> binding CPUs to nodes.
> 
> Also, variable types and names made consistent in functions
> using cpumask.
> 
> Cc: Satheesh Rajendran <sathnaga@...ux.vnet.ibm.com>
> Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
> Cc: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
> Cc: Balamuruhan S <bala24@...ux.vnet.ibm.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Cc: Jiri Olsa <jolsa@...hat.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Signed-off-by: Alexander Gordeev <agordeev@...ux.ibm.com>
> ---
> @@ -310,13 +306,16 @@ static cpu_set_t bind_to_node(int target_node)
>  		for (cpu = 0; cpu < g->p.nr_cpus; cpu++)
>  			CPU_SET(cpu, &mask);
>  	} else {
> -		int cpu_start = (target_node + 0) * cpus_per_node;
> -		int cpu_stop  = (target_node + 1) * cpus_per_node;
> -
> -		BUG_ON(cpu_stop > g->p.nr_cpus);
> +		struct bitmask *cpumask = numa_allocate_cpumask();
> 
> -		for (cpu = cpu_start; cpu < cpu_stop; cpu++)
> -			CPU_SET(cpu, &mask);
> +		BUG_ON(!cpumask);
> +		if (!numa_node_to_cpus(target_node, cpumask)) {
> +			for (cpu = 0; cpu < (int)cpumask->size; cpu++) {
> +				if (numa_bitmask_isbitset(cpumask, cpu))
> +					CPU_SET(cpu, &mask);
> +			}
> +		}
> +		numa_free_cpumask(cpumask);
>  	}
> 
>  	ret = sched_setaffinity(0, sizeof(mask), &mask);
> -- 
> 1.8.3.1
> 

Looks good to me.

Reviewed-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>

-- 
Thanks and Regards
Srikar Dronamraju