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Subject[PATCH 2/8] mm: vmscan: Convert lumpy_mode into a bitmask
Date
Currently lumpy_mode is an enum and determines if lumpy reclaim is off,
syncronous or asyncronous. In preparation for using compaction instead of
lumpy reclaim, this patch converts the flags into a bitmap.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
---
include/trace/events/vmscan.h | 6 ++--
mm/vmscan.c | 46 +++++++++++++++++++++++++----------------
2 files changed, 31 insertions(+), 21 deletions(-)
diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
index c255fcc..be76429 100644
--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h
@@ -25,13 +25,13 @@

#define trace_reclaim_flags(page, sync) ( \
(page_is_file_cache(page) ? RECLAIM_WB_FILE : RECLAIM_WB_ANON) | \
- (sync == LUMPY_MODE_SYNC ? RECLAIM_WB_SYNC : RECLAIM_WB_ASYNC) \
+ (sync & LUMPY_MODE_SYNC ? RECLAIM_WB_SYNC : RECLAIM_WB_ASYNC) \
)

#define trace_shrink_flags(file, sync) ( \
- (sync == LUMPY_MODE_SYNC ? RECLAIM_WB_MIXED : \
+ (sync & LUMPY_MODE_SYNC ? RECLAIM_WB_MIXED : \
(file ? RECLAIM_WB_FILE : RECLAIM_WB_ANON)) | \
- (sync == LUMPY_MODE_SYNC ? RECLAIM_WB_SYNC : RECLAIM_WB_ASYNC) \
+ (sync & LUMPY_MODE_SYNC ? RECLAIM_WB_SYNC : RECLAIM_WB_ASYNC) \
)

TRACE_EVENT(mm_vmscan_kswapd_sleep,
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b8a6fdc..37d4f0e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -51,11 +51,20 @@
#define CREATE_TRACE_POINTS
#include <trace/events/vmscan.h>

-enum lumpy_mode {
- LUMPY_MODE_NONE,
- LUMPY_MODE_ASYNC,
- LUMPY_MODE_SYNC,
-};
+/*
+ * lumpy_mode determines how the inactive list is shrunk
+ * LUMPY_MODE_SINGLE: Reclaim only order-0 pages
+ * LUMPY_MODE_ASYNC: Do not block
+ * LUMPY_MODE_SYNC: Allow blocking e.g. call wait_on_page_writeback
+ * LUMPY_MODE_CONTIGRECLAIM: For high-order allocations, take a reference
+ * page from the LRU and reclaim all pages within a
+ * naturally aligned range
+ */
+typedef unsigned __bitwise__ lumpy_mode;
+#define LUMPY_MODE_SINGLE ((__force lumpy_mode)0x01u)
+#define LUMPY_MODE_ASYNC ((__force lumpy_mode)0x02u)
+#define LUMPY_MODE_SYNC ((__force lumpy_mode)0x04u)
+#define LUMPY_MODE_CONTIGRECLAIM ((__force lumpy_mode)0x08u)

struct scan_control {
/* Incremented by the number of inactive pages that were scanned */
@@ -88,7 +97,7 @@ struct scan_control {
* Intend to reclaim enough continuous memory rather than reclaim
* enough amount of memory. i.e, mode for high order allocation.
*/
- enum lumpy_mode lumpy_reclaim_mode;
+ lumpy_mode lumpy_reclaim_mode;

/* Which cgroup do we reclaim from */
struct mem_cgroup *mem_cgroup;
@@ -274,13 +283,13 @@ unsigned long shrink_slab(unsigned long scanned, gfp_t gfp_mask,
static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc,
bool sync)
{
- enum lumpy_mode mode = sync ? LUMPY_MODE_SYNC : LUMPY_MODE_ASYNC;
+ lumpy_mode mode = sync ? LUMPY_MODE_SYNC : LUMPY_MODE_ASYNC;

/*
* Some reclaim have alredy been failed. No worth to try synchronous
* lumpy reclaim.
*/
- if (sync && sc->lumpy_reclaim_mode == LUMPY_MODE_NONE)
+ if (sync && sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE)
return;

/*
@@ -288,17 +297,18 @@ static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc,
* trouble getting a small set of contiguous pages, we
* will reclaim both active and inactive pages.
*/
+ sc->lumpy_reclaim_mode = LUMPY_MODE_CONTIGRECLAIM;
if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
- sc->lumpy_reclaim_mode = mode;
+ sc->lumpy_reclaim_mode |= mode;
else if (sc->order && priority < DEF_PRIORITY - 2)
- sc->lumpy_reclaim_mode = mode;
+ sc->lumpy_reclaim_mode |= mode;
else
- sc->lumpy_reclaim_mode = LUMPY_MODE_NONE;
+ sc->lumpy_reclaim_mode = LUMPY_MODE_SINGLE | LUMPY_MODE_ASYNC;
}

static void disable_lumpy_reclaim_mode(struct scan_control *sc)
{
- sc->lumpy_reclaim_mode = LUMPY_MODE_NONE;
+ sc->lumpy_reclaim_mode = LUMPY_MODE_SINGLE | LUMPY_MODE_ASYNC;
}

static inline int is_page_cache_freeable(struct page *page)
@@ -429,7 +439,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
* first attempt to free a range of pages fails.
*/
if (PageWriteback(page) &&
- sc->lumpy_reclaim_mode == LUMPY_MODE_SYNC)
+ (sc->lumpy_reclaim_mode & LUMPY_MODE_SYNC))
wait_on_page_writeback(page);

if (!PageWriteback(page)) {
@@ -615,7 +625,7 @@ static enum page_references page_check_references(struct page *page,
referenced_page = TestClearPageReferenced(page);

/* Lumpy reclaim - ignore references */
- if (sc->lumpy_reclaim_mode != LUMPY_MODE_NONE)
+ if (sc->lumpy_reclaim_mode & LUMPY_MODE_CONTIGRECLAIM)
return PAGEREF_RECLAIM;

/*
@@ -732,7 +742,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
* for any page for which writeback has already
* started.
*/
- if (sc->lumpy_reclaim_mode == LUMPY_MODE_SYNC &&
+ if ((sc->lumpy_reclaim_mode & LUMPY_MODE_SYNC) &&
may_enter_fs)
wait_on_page_writeback(page);
else {
@@ -1317,7 +1327,7 @@ static inline bool should_reclaim_stall(unsigned long nr_taken,
return false;

/* Only stall on lumpy reclaim */
- if (sc->lumpy_reclaim_mode == LUMPY_MODE_NONE)
+ if (sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE)
return false;

/* If we have relaimed everything on the isolated list, no stall */
@@ -1368,7 +1378,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
if (scanning_global_lru(sc)) {
nr_taken = isolate_pages_global(nr_to_scan,
&page_list, &nr_scanned, sc->order,
- sc->lumpy_reclaim_mode == LUMPY_MODE_NONE ?
+ sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE ?
ISOLATE_INACTIVE : ISOLATE_BOTH,
zone, 0, file);
zone->pages_scanned += nr_scanned;
@@ -1381,7 +1391,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
} else {
nr_taken = mem_cgroup_isolate_pages(nr_to_scan,
&page_list, &nr_scanned, sc->order,
- sc->lumpy_reclaim_mode == LUMPY_MODE_NONE ?
+ sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE ?
ISOLATE_INACTIVE : ISOLATE_BOTH,
zone, sc->mem_cgroup,
0, file);
--
1.7.1


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