This patch makes optimistic check for swapin readahead to increase thp collapse rate. Before getting swapped out pages to memory, checks them and allows up to a certain number. It also prints out using tracepoints amount of unmapped ptes. Signed-off-by: Ebru Akagunduz <ebru.akagunduz@xxxxxxxxx> --- Changes in v2: - Nothing changed Changes in v3: - Define constant to specify exact tracepoint result (Vlastimil Babka) include/linux/mm.h | 1 + include/trace/events/huge_memory.h | 11 +++++++---- mm/huge_memory.c | 15 ++++++++++++--- 3 files changed, 20 insertions(+), 7 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index bf341c0..eacf348 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -38,6 +38,7 @@ #define MM_ALLOC_HUGE_PAGE_FAIL 6 #define MM_CGROUP_CHARGE_FAIL 7 #define MM_COLLAPSE_ISOLATE_FAIL 5 +#define MM_EXCEED_SWAP_PTE 2 struct mempolicy; struct anon_vma; diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h index cbc56fc..b6bdcc4 100644 --- a/include/trace/events/huge_memory.h +++ b/include/trace/events/huge_memory.h @@ -9,9 +9,9 @@ TRACE_EVENT(mm_khugepaged_scan_pmd, TP_PROTO(struct mm_struct *mm, struct page *page, bool writable, - bool referenced, int none_or_zero, int ret), + bool referenced, int none_or_zero, int ret, int unmapped), - TP_ARGS(mm, page, writable, referenced, none_or_zero, ret), + TP_ARGS(mm, page, writable, referenced, none_or_zero, ret, unmapped), TP_STRUCT__entry( __field(struct mm_struct *, mm) @@ -20,6 +20,7 @@ TRACE_EVENT(mm_khugepaged_scan_pmd, __field(bool, referenced) __field(int, none_or_zero) __field(int, ret) + __field(int, unmapped) ), TP_fast_assign( @@ -29,15 +30,17 @@ TRACE_EVENT(mm_khugepaged_scan_pmd, __entry->referenced = referenced; __entry->none_or_zero = none_or_zero; __entry->ret = ret; + __entry->unmapped = unmapped; ), - TP_printk("mm=%p, page=%p, writable=%d, referenced=%d, none_or_zero=%d, ret=%d", + TP_printk("mm=%p, page=%p, writable=%d, referenced=%d, none_or_zero=%d, ret=%d, unmapped=%d", __entry->mm, __entry->page, __entry->writable, __entry->referenced, __entry->none_or_zero, - __entry->ret) + __entry->ret, + __entry->unmapped) ); TRACE_EVENT(mm_collapse_huge_page, diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 595edd9..b4cef9d 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -24,6 +24,7 @@ #include <linux/migrate.h> #include <linux/hashtable.h> #include <linux/userfaultfd_k.h> +#include <linux/swapops.h> #include <asm/tlb.h> #include <asm/pgalloc.h> @@ -2671,11 +2672,11 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, { pmd_t *pmd; pte_t *pte, *_pte; - int ret = 0, none_or_zero = 0; + int ret = 0, none_or_zero = 0, unmapped = 0; struct page *page = NULL; unsigned long _address; spinlock_t *ptl; - int node = NUMA_NO_NODE; + int node = NUMA_NO_NODE, max_ptes_swap = HPAGE_PMD_NR/8; bool writable = false, referenced = false; VM_BUG_ON(address & ~HPAGE_PMD_MASK); @@ -2691,6 +2692,14 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++, _address += PAGE_SIZE) { pte_t pteval = *_pte; + if (is_swap_pte(pteval)) { + if (++unmapped <= max_ptes_swap) { + continue; + } else { + ret = MM_EXCEED_SWAP_PTE; + goto out_unmap; + } + } if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { if (!userfaultfd_armed(vma) && ++none_or_zero <= khugepaged_max_ptes_none) { @@ -2755,7 +2764,7 @@ out_unmap: } out: trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, - none_or_zero, ret); + none_or_zero, ret, unmapped); return ret; } -- 1.9.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>