This patch introduces 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.
Signed-off-by: Ebru Akagunduz <[email protected]> --- Changes in v2: - Nothing changed Changes in v3: - Define constant for exact tracepoint result (Vlastimil Babka) Changes in v4: - Add sysfs knob request (Kirill A. Shutemov) include/trace/events/huge_memory.h | 10 ++++---- mm/huge_memory.c | 48 ++++++++++++++++++++++++++++++++++---- 2 files changed, 50 insertions(+), 8 deletions(-) diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h index 36162a9..c2112fd 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, unsigned long pfn, bool writable, - bool referenced, int none_or_zero, int status), + bool referenced, int none_or_zero, int status, int unmapped), - TP_ARGS(mm, pfn, writable, referenced, none_or_zero, status), + TP_ARGS(mm, pfn, writable, referenced, none_or_zero, status, 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, status) + __field(int, unmapped) ), TP_fast_assign( @@ -31,13 +32,14 @@ TRACE_EVENT(mm_khugepaged_scan_pmd, __entry->status = status; ), - 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, - khugepaged_status_string[__entry->status]) + khugepaged_status_string[__entry->status], + __entry->unmapped) ); TRACE_EVENT(mm_collapse_huge_page, diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 71a7c43..cb9ab46 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -23,6 +23,7 @@ #include <linux/pagemap.h> #include <linux/migrate.h> #include <linux/hashtable.h> +#include <linux/swapops.h> #include <asm/tlb.h> #include <asm/pgalloc.h> @@ -49,7 +50,8 @@ static const char *const khugepaged_status_string[] = { "page_swap_cache", "could_not_delete_page_from_lru", "alloc_huge_page_fail", - "ccgroup_charge_fail" + "ccgroup_charge_fail", + "exceed_swap_pte" }; enum scan_result { @@ -73,7 +75,8 @@ enum scan_result { SCAN_SWAP_CACHE_PAGE, SCAN_DEL_PAGE_LRU, SCAN_ALLOC_HUGE_PAGE_FAIL, - SCAN_CGROUP_CHARGE_FAIL + SCAN_CGROUP_CHARGE_FAIL, + MM_EXCEED_SWAP_PTE }; #define CREATE_TRACE_POINTS @@ -115,6 +118,7 @@ static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait); * fault. */ static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1; +static unsigned int khugepaged_max_ptes_swap __read_mostly = HPAGE_PMD_NR/8; static int khugepaged(void *none); static int khugepaged_slab_init(void); @@ -607,6 +611,33 @@ static struct kobj_attribute khugepaged_max_ptes_none_attr = __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, @@ -615,6 +646,7 @@ 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, }; @@ -2664,7 +2696,7 @@ static int khugepaged_scan_pmd(struct mm_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); @@ -2680,6 +2712,14 @@ 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 <= khugepaged_max_ptes_swap) { + continue; + } else { + result = MM_EXCEED_SWAP_PTE; + goto out_unmap; + } + } if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { if (++none_or_zero <= khugepaged_max_ptes_none) { continue; @@ -2757,7 +2797,7 @@ out_unmap: } out: trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, referenced, - none_or_zero, result); + none_or_zero, result, unmapped); return ret; } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
