From a1a3a2fc304df326ff67a1814364f640f2d5121c Mon Sep 17 00:00:00 2001 From: Huang Ying Date: Tue, 22 Mar 2022 14:46:27 -0700 Subject: [PATCH] memory tiering: skip to scan fast memory If the NUMA balancing isn't used to optimize the page placement among sockets but only among memory types, the hot pages in the fast memory node couldn't be migrated (promoted) to anywhere. So it's unnecessary to scan the pages in the fast memory node via changing their PTE/PMD mapping to be PROT_NONE. So that the page faults could be avoided too. In the test, if only the memory tiering NUMA balancing mode is enabled, the number of the NUMA balancing hint faults for the DRAM node is reduced to almost 0 with the patch. While the benchmark score doesn't change visibly. Link: https://lkml.kernel.org/r/20220221084529.1052339-4-ying.huang@intel.com Signed-off-by: "Huang, Ying" Suggested-by: Dave Hansen Tested-by: Baolin Wang Reviewed-by: Baolin Wang Acked-by: Johannes Weiner Reviewed-by: Oscar Salvador Reviewed-by: Yang Shi Cc: Michal Hocko Cc: Rik van Riel Cc: Mel Gorman Cc: Peter Zijlstra Cc: Zi Yan Cc: Wei Xu Cc: Shakeel Butt Cc: zhongjiang-ali Cc: Feng Tang Cc: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 30 +++++++++++++++++++++--------- mm/mprotect.c | 13 ++++++++++++- 2 files changed, 33 insertions(+), 10 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 9c52b36..88c83c8 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -34,6 +34,7 @@ #include #include #include +#include #include #include @@ -1766,17 +1767,28 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd, } #endif - /* - * Avoid trapping faults against the zero page. The read-only - * data is likely to be read-cached on the local CPU and - * local/remote hits to the zero page are not interesting. - */ - if (prot_numa && is_huge_zero_pmd(*pmd)) - goto unlock; + if (prot_numa) { + struct page *page; + /* + * Avoid trapping faults against the zero page. The read-only + * data is likely to be read-cached on the local CPU and + * local/remote hits to the zero page are not interesting. + */ + if (is_huge_zero_pmd(*pmd)) + goto unlock; - if (prot_numa && pmd_protnone(*pmd)) - goto unlock; + if (pmd_protnone(*pmd)) + goto unlock; + page = pmd_page(*pmd); + /* + * Skip scanning top tier node if normal numa + * balancing is disabled + */ + if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && + node_is_toptier(page_to_nid(page))) + goto unlock; + } /* * In case prot_numa, we are under mmap_read_lock(mm). It's critical * to not clear pmd intermittently to avoid race with MADV_DONTNEED diff --git a/mm/mprotect.c b/mm/mprotect.c index 2887644..b69ce7a 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #include #include @@ -83,6 +84,7 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, */ if (prot_numa) { struct page *page; + int nid; /* Avoid TLB flush if possible */ if (pte_protnone(oldpte)) @@ -109,7 +111,16 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd, * Don't mess with PTEs if page is already on the node * a single-threaded process is running on. */ - if (target_node == page_to_nid(page)) + nid = page_to_nid(page); + if (target_node == nid) + continue; + + /* + * Skip scanning top tier node if normal numa + * balancing is disabled + */ + if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && + node_is_toptier(nid)) continue; } -- 2.7.4