Fengguang Wu <fengguang.wu@xxxxxxxxx> writes: > On Tue, Jan 01, 2019 at 02:44:41PM +0530, Aneesh Kumar K.V wrote: >>Fengguang Wu <fengguang.wu@xxxxxxxxx> writes: >> >>> From: Fan Du <fan.du@xxxxxxxxx> >>> >>> When allocate page, DRAM and PMEM node should better not fall back to >>> each other. This allows migration code to explicitly control which type >>> of node to allocate pages from. >>> >>> With this patch, PMEM NUMA node can only be used in 2 ways: >>> - migrate in and out >>> - numactl >> >>Can we achieve this using nodemask? That way we don't tag nodes with >>different properties such as DRAM/PMEM. We can then give the >>flexibilility to the device init code to add the new memory nodes to >>the right nodemask > > Aneesh, in patch 2 we did create nodemask numa_nodes_pmem and > numa_nodes_dram. What's your supposed way of "using nodemask"? > IIUC the patch is to avoid allocation from PMEM nodes and the way you achieve it is by checking if (is_node_pmem(n)). We already have abstractness to avoid allocation from a node using node mask. I was wondering whether we can do the equivalent of above using that. ie, __next_zone_zonelist can do zref_in_nodemask(z, default_exclude_nodemask)) and decide whether to use the specific zone or not. That way we don't add special code like + PGDAT_DRAM, /* Volatile DRAM memory node */ + PGDAT_PMEM, /* Persistent memory node */ The reason is that there could be other device memory that would want to get excluded from that default allocation like you are doing for PMEM -aneesh
