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authorEbru Akagunduz <ebru.akagunduz@gmail.com>2016-07-26 15:24:59 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-26 16:19:19 -0700
commit70652f6ec0566ae6b4147d88c6d043c68484227f (patch)
tree834639192cd3ff32322af52b290ea9b5eda7947c
parentef3cc4db415e0cee73ea37ac6d79821d77f15f1d (diff)
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@parallels.com: fix scan not aborted on SCAN_EXCEED_SWAP_PTE] [sfr@canb.auug.org.au: build fix] Link: http://lkml.kernel.org/r/20160616154503.65806e12@canb.auug.org.au Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Xie XiuQi <xiexiuqi@huawei.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: David Rientjes <rientjes@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/trace/events/huge_memory.h14
-rw-r--r--mm/huge_memory.c45
2 files changed, 51 insertions, 8 deletions
diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h
index 551ba4acde4d..fad6539c9d68 100644
--- a/include/trace/events/huge_memory.h
+++ b/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 --git a/mm/huge_memory.c b/mm/huge_memory.c
index 23d1bf42fef1..ed474483a620 100644
--- a/mm/huge_memory.c
+++ b/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(khugepaged_wait);
* 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_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,
@@ -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 *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_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;
}