There is little motiviation for reclaim_mode_t once RECLAIM_MODE_[A]SYNC
and lumpy reclaim have been removed. This patch gets rid of reclaim_mode_t
as well and improves the documentation about what reclaim/compaction is
and when it is triggered.
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
---
include/trace/events/vmscan.h | 4 +--
mm/vmscan.c | 72 +++++++++++++----------------------------
2 files changed, 24 insertions(+), 52 deletions(-)
diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
index 6f60b33..f66cc93 100644
--- a/include/trace/events/vmscan.h
+++ b/include/trace/events/vmscan.h
@@ -25,12 +25,12 @@
{RECLAIM_WB_ASYNC, "RECLAIM_WB_ASYNC"} \
) : "RECLAIM_WB_NONE"
-#define trace_reclaim_flags(page, sync) ( \
+#define trace_reclaim_flags(page) ( \
(page_is_file_cache(page) ? RECLAIM_WB_FILE : RECLAIM_WB_ANON) | \
(RECLAIM_WB_ASYNC) \
)
-#define trace_shrink_flags(file, sync) ( \
+#define trace_shrink_flags(file) \
( \
(file ? RECLAIM_WB_FILE : RECLAIM_WB_ANON) | \
(RECLAIM_WB_ASYNC) \
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 68319e4..36c6ad2 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -53,16 +53,6 @@
#define CREATE_TRACE_POINTS
#include <trace/events/vmscan.h>
-/*
- * reclaim_mode determines how the inactive list is shrunk
- * RECLAIM_MODE_SINGLE: Reclaim only order-0 pages
- * RECLAIM_MODE_COMPACTION: For high-order allocations, reclaim a number of
- * order-0 pages and then compact the zone
- */
-typedef unsigned __bitwise__ reclaim_mode_t;
-#define RECLAIM_MODE_SINGLE ((__force reclaim_mode_t)0x01u)
-#define RECLAIM_MODE_COMPACTION ((__force reclaim_mode_t)0x10u)
-
struct scan_control {
/* Incremented by the number of inactive pages that were scanned */
unsigned long nr_scanned;
@@ -89,12 +79,6 @@ struct scan_control {
int order;
/*
- * Intend to reclaim enough continuous memory rather than reclaim
- * enough amount of memory. i.e, mode for high order allocation.
- */
- reclaim_mode_t reclaim_mode;
-
- /*
* The memory cgroup that hit its limit and as a result is the
* primary target of this reclaim invocation.
*/
@@ -356,25 +340,6 @@ out:
return ret;
}
-static void set_reclaim_mode(int priority, struct scan_control *sc)
-{
- /*
- * Restrict reclaim/compaction to costly allocations or when
- * under memory pressure
- */
- if (COMPACTION_BUILD && sc->order &&
- (sc->order > PAGE_ALLOC_COSTLY_ORDER ||
- priority < DEF_PRIORITY - 2))
- sc->reclaim_mode = RECLAIM_MODE_COMPACTION;
- else
- sc->reclaim_mode = RECLAIM_MODE_SINGLE;
-}
-
-static void reset_reclaim_mode(struct scan_control *sc)
-{
- sc->reclaim_mode = RECLAIM_MODE_SINGLE;
-}
-
static inline int is_page_cache_freeable(struct page *page)
{
/*
@@ -497,8 +462,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
/* synchronous write or broken a_ops? */
ClearPageReclaim(page);
}
- trace_mm_vmscan_writepage(page,
- trace_reclaim_flags(page, sc->reclaim_mode));
+ trace_mm_vmscan_writepage(page, trace_reclaim_flags(page));
inc_zone_page_state(page, NR_VMSCAN_WRITE);
return PAGE_SUCCESS;
}
@@ -953,7 +917,6 @@ cull_mlocked:
try_to_free_swap(page);
unlock_page(page);
putback_lru_page(page);
- reset_reclaim_mode(sc);
continue;
activate_locked:
@@ -1348,8 +1311,6 @@ shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz,
return SWAP_CLUSTER_MAX;
}
- set_reclaim_mode(priority, sc);
-
lru_add_drain();
if (!sc->may_unmap)
@@ -1428,7 +1389,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct mem_cgroup_zone *mz,
zone_idx(zone),
nr_scanned, nr_reclaimed,
priority,
- trace_shrink_flags(file, sc->reclaim_mode));
+ trace_shrink_flags(file));
return nr_reclaimed;
}
@@ -1507,8 +1468,6 @@ static void shrink_active_list(unsigned long nr_to_scan,
lru_add_drain();
- reset_reclaim_mode(sc);
-
if (!sc->may_unmap)
isolate_mode |= ISOLATE_UNMAPPED;
if (!sc->may_writepage)
@@ -1821,23 +1780,35 @@ out:
}
}
+/* Use reclaim/compaction for costly allocs or under memory pressure */
+static bool in_reclaim_compaction(int priority, struct scan_control *sc)
+{
+ if (COMPACTION_BUILD && sc->order &&
+ (sc->order > PAGE_ALLOC_COSTLY_ORDER ||
+ priority < DEF_PRIORITY - 2))
+ return true;
+
+ return false;
+}
+
/*
- * Reclaim/compaction depends on a number of pages being freed. To avoid
- * disruption to the system, a small number of order-0 pages continue to be
- * rotated and reclaimed in the normal fashion. However, by the time we get
- * back to the allocator and call try_to_compact_zone(), we ensure that
- * there are enough free pages for it to be likely successful
+ * Reclaim/compaction is used for high-order allocation requests. It reclaims
+ * order-0 pages before compacting the zone. should_continue_reclaim() returns
+ * true if more pages should be reclaimed such that when the page allocator
+ * calls try_to_compact_zone() that it will have enough free pages to succeed.
+ * It will give up earlier than that if there is difficulty reclaiming pages.
*/
static inline bool should_continue_reclaim(struct mem_cgroup_zone *mz,
unsigned long nr_reclaimed,
unsigned long nr_scanned,
+ int priority,
struct scan_control *sc)
{
unsigned long pages_for_compaction;
unsigned long inactive_lru_pages;
/* If not in reclaim/compaction mode, stop */
- if (!(sc->reclaim_mode & RECLAIM_MODE_COMPACTION))
+ if (!in_reclaim_compaction(priority, sc))
return false;
/* Consider stopping depending on scan and reclaim activity */
@@ -1944,7 +1915,8 @@ restart:
/* reclaim/compaction might need reclaim to continue */
if (should_continue_reclaim(mz, nr_reclaimed,
- sc->nr_scanned - nr_scanned, sc))
+ sc->nr_scanned - nr_scanned,
+ priority, sc))
goto restart;
throttle_vm_writeout(sc->gfp_mask);
--
1.7.9.2
--
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