Re: [PATCH v7 11/14] arm64/numa: support HAVE_MEMORYLESS_NODES

["Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>]

On 2016/8/26 23:43, Will Deacon wrote:
> On Wed, Aug 24, 2016 at 03:44:50PM +0800, Zhen Lei wrote:
>> Some numa nodes may have no memory. For example:
>> 1. cpu0 on node0
>> 2. cpu1 on node1
>> 3. device0 access the momory from node0 and node1 take the same time.
>>
>> So, we can not simply classify device0 to node0 or node1, but we can
>> define a node2 which distances to node0 and node1 are the same.
>>
>> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
>> ---
>>  arch/arm64/Kconfig      |  4 ++++
>>  arch/arm64/kernel/smp.c |  1 +
>>  arch/arm64/mm/numa.c    | 43 +++++++++++++++++++++++++++++++++++++++++--
>>  3 files changed, 46 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index 2815af6..3a2b6ed 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -611,6 +611,10 @@ config NEED_PER_CPU_EMBED_FIRST_CHUNK
>>  	def_bool y
>>  	depends on NUMA
>>
>> +config HAVE_MEMORYLESS_NODES
>> +	def_bool y
>> +	depends on NUMA
>> +
>>  source kernel/Kconfig.preempt
>>  source kernel/Kconfig.hz
>>
>> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
>> index d93d433..4879085 100644
>> --- a/arch/arm64/kernel/smp.c
>> +++ b/arch/arm64/kernel/smp.c
>> @@ -619,6 +619,7 @@ static void __init of_parse_and_init_cpus(void)
>>  			}
>>
>>  			bootcpu_valid = true;
>> +			early_map_cpu_to_node(0, of_node_to_nid(dn));
> 
> This seems unrelated?
I will get off my work soon. Maybe I need put it into patch 12.

> 
>>  			/*
>>  			 * cpu_logical_map has already been
>> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
>> index 6853db7..114180f 100644
>> --- a/arch/arm64/mm/numa.c
>> +++ b/arch/arm64/mm/numa.c
>> @@ -129,6 +129,14 @@ void __init early_map_cpu_to_node(unsigned int cpu, int nid)
>>  		nid = 0;
>>
>>  	cpu_to_node_map[cpu] = nid;
>> +
>> +	/*
>> +	 * We should set the numa node of cpu0 as soon as possible, because it
>> +	 * has already been set up online before. cpu_to_node(0) will soon be
>> +	 * called.
>> +	 */
>> +	if (!cpu)
>> +		set_cpu_numa_node(cpu, nid);
> 
> Likewise.
> 
>>  }
>>
>>  #ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
>> @@ -211,6 +219,35 @@ int __init numa_add_memblk(int nid, u64 start, u64 end)
>>  	return ret;
>>  }
>>
>> +static u64 __init alloc_node_data_from_nearest_node(int nid, const size_t size)
>> +{
>> +	int i, best_nid, distance;
>> +	u64 pa;
>> +	DECLARE_BITMAP(nodes_map, MAX_NUMNODES);
>> +
>> +	bitmap_zero(nodes_map, MAX_NUMNODES);
>> +	bitmap_set(nodes_map, nid, 1);
>> +
>> +find_nearest_node:
>> +	best_nid = NUMA_NO_NODE;
>> +	distance = INT_MAX;
>> +
>> +	for_each_clear_bit(i, nodes_map, MAX_NUMNODES)
>> +		if (numa_distance[nid][i] < distance) {
>> +			best_nid = i;
>> +			distance = numa_distance[nid][i];
>> +		}
>> +
>> +	pa = memblock_alloc_nid(size, SMP_CACHE_BYTES, best_nid);
>> +	if (!pa) {
>> +		BUG_ON(best_nid == NUMA_NO_NODE);
>> +		bitmap_set(nodes_map, best_nid, 1);
>> +		goto find_nearest_node;
>> +	}
>> +
>> +	return pa;
>> +}
>> +
>>  /**
>>   * Initialize NODE_DATA for a node on the local memory
>>   */
>> @@ -224,7 +261,9 @@ static void __init setup_node_data(int nid, u64 start_pfn, u64 end_pfn)
>>  	pr_info("Initmem setup node %d [mem %#010Lx-%#010Lx]\n",
>>  		nid, start_pfn << PAGE_SHIFT, (end_pfn << PAGE_SHIFT) - 1);
>>
>> -	nd_pa = memblock_alloc_try_nid(nd_size, SMP_CACHE_BYTES, nid);
>> +	nd_pa = memblock_alloc_nid(nd_size, SMP_CACHE_BYTES, nid);
>> +	if (!nd_pa)
>> +		nd_pa = alloc_node_data_from_nearest_node(nid, nd_size);
> 
> Why not add memblock_alloc_near_nid to the core code, and make it do
> what you need there?
I'm thinking about it next week. But some ARCHs like X86/IA64 have their own implementation.

> 
> Will
> 
> .
>