From: Ebru Akagunduz <ebru.akagunduz@xxxxxxxxx> Subject: mm: make optimistic check for swapin readahead Introduce a new sysfs integer knob /sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_swap which 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. [vdavydov@xxxxxxxxxxxxx: fix scan not aborted on SCAN_EXCEED_SWAP_PTE] [sfr@xxxxxxxxxxxxxxxx: build fix] Link: http://lkml.kernel.org/r/20160616154503.65806e12@xxxxxxxxxxxxxxxx Signed-off-by: Ebru Akagunduz <ebru.akagunduz@xxxxxxxxx> Acked-by: Rik van Riel <riel@xxxxxxxxxx> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Xie XiuQi <xiexiuqi@xxxxxxxxxx> Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxx> Signed-off-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/trace/events/huge_memory.h | 14 +++++--- mm/huge_memory.c | 45 +++++++++++++++++++++++++-- 2 files changed, 51 insertions(+), 8 deletions(-) diff -puN include/trace/events/huge_memory.h~mm-make-optimistic-check-for-swapin-readahead include/trace/events/huge_memory.h --- a/include/trace/events/huge_memory.h~mm-make-optimistic-check-for-swapin-readahead +++ a/include/trace/events/huge_memory.h @@ -28,7 +28,8 @@ EM( SCAN_SWAP_CACHE_PAGE, "page_swap_cache") \ EM( SCAN_DEL_PAGE_LRU, "could_not_delete_page_from_lru")\ EM( SCAN_ALLOC_HUGE_PAGE_FAIL, "alloc_huge_page_failed") \ - EMe( SCAN_CGROUP_CHARGE_FAIL, "ccgroup_charge_failed") + EM( SCAN_CGROUP_CHARGE_FAIL, "ccgroup_charge_failed") \ + EMe( SCAN_EXCEED_SWAP_PTE, "exceed_swap_pte") #undef EM #undef EMe @@ -45,9 +46,9 @@ SCAN_STATUS TRACE_EVENT(mm_khugepaged_scan_pmd, TP_PROTO(struct mm_struct *mm, struct page *page, bool writable, - bool referenced, int none_or_zero, int status), + bool referenced, int none_or_zero, int status, int unmapped), - TP_ARGS(mm, page, writable, referenced, none_or_zero, status), + TP_ARGS(mm, page, writable, referenced, none_or_zero, status, unmapped), TP_STRUCT__entry( __field(struct mm_struct *, mm) @@ -56,6 +57,7 @@ TRACE_EVENT(mm_khugepaged_scan_pmd, __field(bool, referenced) __field(int, none_or_zero) __field(int, status) + __field(int, unmapped) ), TP_fast_assign( @@ -65,15 +67,17 @@ TRACE_EVENT(mm_khugepaged_scan_pmd, __entry->referenced = referenced; __entry->none_or_zero = none_or_zero; __entry->status = status; + __entry->unmapped = unmapped; ), - TP_printk("mm=%p, scan_pfn=0x%lx, writable=%d, referenced=%d, none_or_zero=%d, status=%s", + TP_printk("mm=%p, scan_pfn=0x%lx, writable=%d, referenced=%d, none_or_zero=%d, status=%s, unmapped=%d", __entry->mm, __entry->pfn, __entry->writable, __entry->referenced, __entry->none_or_zero, - __print_symbolic(__entry->status, SCAN_STATUS)) + __print_symbolic(__entry->status, SCAN_STATUS), + __entry->unmapped) ); TRACE_EVENT(mm_collapse_huge_page, diff -puN mm/huge_memory.c~mm-make-optimistic-check-for-swapin-readahead mm/huge_memory.c --- a/mm/huge_memory.c~mm-make-optimistic-check-for-swapin-readahead +++ a/mm/huge_memory.c @@ -57,7 +57,8 @@ enum scan_result { SCAN_SWAP_CACHE_PAGE, SCAN_DEL_PAGE_LRU, SCAN_ALLOC_HUGE_PAGE_FAIL, - SCAN_CGROUP_CHARGE_FAIL + SCAN_CGROUP_CHARGE_FAIL, + SCAN_EXCEED_SWAP_PTE }; #define CREATE_TRACE_POINTS @@ -100,6 +101,7 @@ static DECLARE_WAIT_QUEUE_HEAD(khugepage * fault. */ static unsigned int khugepaged_max_ptes_none __read_mostly; +static unsigned int khugepaged_max_ptes_swap __read_mostly; static int khugepaged(void *none); static int khugepaged_slab_init(void); @@ -598,6 +600,33 @@ static struct kobj_attribute khugepaged_ __ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show, khugepaged_max_ptes_none_store); +static ssize_t khugepaged_max_ptes_swap_show(struct kobject *kobj, + struct kobj_attribute *attr, + char *buf) +{ + return sprintf(buf, "%u\n", khugepaged_max_ptes_swap); +} + +static ssize_t khugepaged_max_ptes_swap_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + int err; + unsigned long max_ptes_swap; + + err = kstrtoul(buf, 10, &max_ptes_swap); + if (err || max_ptes_swap > HPAGE_PMD_NR-1) + return -EINVAL; + + khugepaged_max_ptes_swap = max_ptes_swap; + + return count; +} + +static struct kobj_attribute khugepaged_max_ptes_swap_attr = + __ATTR(max_ptes_swap, 0644, khugepaged_max_ptes_swap_show, + khugepaged_max_ptes_swap_store); + static struct attribute *khugepaged_attr[] = { &khugepaged_defrag_attr.attr, &khugepaged_max_ptes_none_attr.attr, @@ -606,6 +635,7 @@ static struct attribute *khugepaged_attr &full_scans_attr.attr, &scan_sleep_millisecs_attr.attr, &alloc_sleep_millisecs_attr.attr, + &khugepaged_max_ptes_swap_attr.attr, NULL, }; @@ -674,6 +704,7 @@ static int __init hugepage_init(void) khugepaged_pages_to_scan = HPAGE_PMD_NR * 8; khugepaged_max_ptes_none = HPAGE_PMD_NR - 1; + khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8; /* * hugepages can't be allocated by the buddy allocator */ @@ -2507,7 +2538,7 @@ static int khugepaged_scan_pmd(struct mm struct page *page = NULL; unsigned long _address; spinlock_t *ptl; - int node = NUMA_NO_NODE; + int node = NUMA_NO_NODE, unmapped = 0; bool writable = false, referenced = false; VM_BUG_ON(address & ~HPAGE_PMD_MASK); @@ -2523,6 +2554,14 @@ static int khugepaged_scan_pmd(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 <= khugepaged_max_ptes_swap) { + continue; + } else { + result = SCAN_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) { @@ -2609,7 +2648,7 @@ out_unmap: } out: trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced, - none_or_zero, result); + none_or_zero, result, unmapped); return ret; } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
