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Subject[PATCH 2/2] lumpy: increase pressure at the end of the inactive list cleanups
Date

Cleanups following review feedback for the patch below:

lumpy: increase pressure at the end of the inactive list

This patch:

1) introduces ISOLATE_[ACTIVE,INACTIVE],
2) changes the name of the deactivate_pages() helper to clear_active_flags(),
3) cleans up and simplifies the checks in __isolate_lru_pages(), and
4) changes the parameter active to mode throughout.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
---
diff --git a/mm/vmscan.c b/mm/vmscan.c
index ab7f4c0..5f3c2bb 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -590,38 +590,46 @@ keep:
return nr_reclaimed;
}

+/* LRU Isolation modes. */
+#define ISOLATE_INACTIVE 0 /* Isolate inactive pages. */
+#define ISOLATE_ACTIVE 1 /* Isolate active pages. */
+#define ISOLATE_BOTH 2 /* Isolate both active and inactive pages. */
+
/*
* Attempt to remove the specified page from its LRU. Only take this page
* if it is of the appropriate PageActive status. Pages which are being
* freed elsewhere are also ignored.
*
* page: page to consider
- * active: active/inactive flag only take pages of this type
+ * mode: one of the LRU isolation modes defined above
*
* returns 0 on success, -ve errno on failure.
*/
-#define ISOLATE_BOTH -1 /* Isolate both active and inactive pages. */
-static int __isolate_lru_page(struct page *page, int active)
+static int __isolate_lru_page(struct page *page, int mode)
{
int ret = -EINVAL;

+ /* Only take pages on the LRU. */
+ if (!PageLRU(page))
+ return ret;
+
/*
* When checking the active state, we need to be sure we are
* dealing with comparible boolean values. Take the logical not
* of each.
*/
- if (PageLRU(page) && (active == ISOLATE_BOTH ||
- (!PageActive(page) == !active))) {
- ret = -EBUSY;
- if (likely(get_page_unless_zero(page))) {
- /*
- * Be careful not to clear PageLRU until after we're
- * sure the page is not being freed elsewhere -- the
- * page release code relies on it.
- */
- ClearPageLRU(page);
- ret = 0;
- }
+ if (mode != ISOLATE_BOTH && (!PageActive(page) != !mode))
+ return ret;
+
+ ret = -EBUSY;
+ if (likely(get_page_unless_zero(page))) {
+ /*
+ * Be careful not to clear PageLRU until after we're
+ * sure the page is not being freed elsewhere -- the
+ * page release code relies on it.
+ */
+ ClearPageLRU(page);
+ ret = 0;
}

return ret;
@@ -642,13 +650,13 @@ static int __isolate_lru_page(struct page *page, int active)
* @dst: The temp list to put pages on to.
* @scanned: The number of pages that were scanned.
* @order: The caller's attempted allocation order
- * @active: The caller's trying to obtain active or inactive pages
+ * @mode: One of the LRU isolation modes
*
* returns how many pages were moved onto *@dst.
*/
static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
struct list_head *src, struct list_head *dst,
- unsigned long *scanned, int order, int active)
+ unsigned long *scanned, int order, int mode)
{
unsigned long nr_taken = 0;
unsigned long scan;
@@ -665,7 +673,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,

VM_BUG_ON(!PageLRU(page));

- switch (__isolate_lru_page(page, active)) {
+ switch (__isolate_lru_page(page, mode)) {
case 0:
list_move(&page->lru, dst);
nr_taken++;
@@ -711,7 +719,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
/* Check that we have not crossed a zone boundary. */
if (unlikely(page_zone_id(cursor_page) != zone_id))
continue;
- switch (__isolate_lru_page(cursor_page, active)) {
+ switch (__isolate_lru_page(cursor_page, mode)) {
case 0:
list_move(&cursor_page->lru, dst);
nr_taken++;
@@ -732,21 +740,19 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
}

/*
- * deactivate_pages() is a helper for shrink_active_list(), it deactivates
- * all active pages on the passed list.
+ * clear_active_flags() is a helper for shrink_active_list(), clearing
+ * any active bits from the pages in the list.
*/
-static unsigned long deactivate_pages(struct list_head *page_list)
+static unsigned long clear_active_flags(struct list_head *page_list)
{
int nr_active = 0;
- struct list_head *entry;
+ struct page *page;

- list_for_each(entry, page_list) {
- struct page *page = list_entry(entry, struct page, lru);
+ list_for_each_entry(page, page_list, lru)
if (PageActive(page)) {
ClearPageActive(page);
nr_active++;
}
- }

return nr_active;
}
@@ -778,8 +784,8 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
&zone->inactive_list,
&page_list, &nr_scan, sc->order,
(sc->order > PAGE_ALLOC_COSTLY_ORDER)?
- ISOLATE_BOTH : 0);
- nr_active = deactivate_pages(&page_list);
+ ISOLATE_BOTH : ISOLATE_INACTIVE);
+ nr_active = clear_active_flags(&page_list);

__mod_zone_page_state(zone, NR_ACTIVE, -nr_active);
__mod_zone_page_state(zone, NR_INACTIVE,
@@ -929,7 +935,7 @@ force_reclaim_mapped:
lru_add_drain();
spin_lock_irq(&zone->lru_lock);
pgmoved = isolate_lru_pages(nr_pages, &zone->active_list,
- &l_hold, &pgscanned, sc->order, 1);
+ &l_hold, &pgscanned, sc->order, ISOLATE_ACTIVE);
zone->pages_scanned += pgscanned;
__mod_zone_page_state(zone, NR_ACTIVE, -pgmoved);
spin_unlock_irq(&zone->lru_lock);
-
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