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

From: [email-masked] (Leizhen (ThunderTown))
Date: Mon, 29 Aug 2016 11:15:55 +0800

On 2016/8/27 19:05, Leizhen (ThunderTown) wrote:
> 
> 
> 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 <[email-masked]>
>>> ---
>>>  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.

Do you mean directly and only call alloc_node_data_from_nearest_node? OK, that's fine. Thanks.

>> Will
>> .