[Pmem] Re: [PATCH] memory tiered: Do not use thp in pmem node

Currently, Mysql testcase show that a large number of thp are migrated from pmem node to toptier node, it will bring in more pgpromote_demoted and migrated failiure. because pmem node memory is marked as prot_none, it will be migrated by cpu access as soon as possible when it is hot, and it is unnesscessary to migrate thp to dram when dram memory is not enough, which will bring in more demoted and promoted. Hence, the patch forbid the thp to produce in pmem node. the result show about 3% improvements. the relative statistics is as follows. before appling patch: mysql prepare: pgpromote_demoted 908267 pgmigrate_fail_dst_node_fail 428223 pgmigrate_fail_numa_isolate_fail 460480 mysql run: pgpromote_demoted 2901105 pgmigrate_fail_dst_node_fail 5653776 pgmigrate_fail_numa_isolate_fail 5686052 after appling patch: mysql prepare: pgpromote_demoted 839297 pgmigrate_fail_dst_node_fail 36585 pgmigrate_fail_numa_isolate_fail 36585 mysql run: pgpromote_demoted 913828 pgmigrate_fail_dst_node_fail 235863 pgmigrate_fail_numa_isolate_fail 235870 Signed-off-by: zhongjiang-ali <zhongjiang-ali(a)linux.alibaba.com> --- mm/page_alloc.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 8cfce92..4fff3cd 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -461,6 +461,17 @@ static __always_inline int get_pfnblock_migratetype(struct page *page, unsigned return __get_pfnblock_flags_mask(page, pfn, PB_migrate_end, MIGRATETYPE_MASK); } +static inline bool allow_hugepage_allocation(int nid, unsigned int order) +{ + if (node_is_toptier(nid)) + return true; + + if (order != HPAGE_PMD_ORDER) + return true; + + return false; +} + /** * set_pfnblock_flags_mask - Set the requested group of flags for a pageblock_nr_pages block of pages * @page: The page within the block of interest @@ -3689,6 +3700,9 @@ static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone) } } + if (!allow_hugepage_allocation(zone_to_nid(zone), order)) + continue; +