Reclaim priorities range from 0..12(DEF_PRIORITY).
scan_control.priority is a 4 byte int, which is overkill.
Since commit 6538b8ea886e ("x86_64: expand kernel stack to 16K") x86_64
stack overflows are not an issue. But it's inefficient to use 4 bytes
for priority.
Use s8 (signed byte) rather than u8 to allow for loops like:
do {
...
} while (--sc.priority >= 0);
This reduces sizeof(struct scan_control) from 96 => 88 bytes (x86_64),
which saves some stack.
scan_control.priority field order is changed to occupy otherwise unused
padding.
Signed-off-by: Greg Thelen <gthelen@xxxxxxxxxx>
---
mm/vmscan.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9b697323a88c..541c334bd176 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -83,9 +83,6 @@ struct scan_control {
*/
struct mem_cgroup *target_mem_cgroup;
- /* Scan (total_size >> priority) pages at once */
- int priority;
-
/* The highest zone to isolate pages for reclaim from */
enum zone_type reclaim_idx;
@@ -111,6 +108,9 @@ struct scan_control {
/* One of the zones is ready for compaction */
unsigned int compaction_ready:1;
+ /* Scan (total_size >> priority) pages at once */
+ s8 priority;
+
/* Incremented by the number of inactive pages that were scanned */
unsigned long nr_scanned;
--
2.17.0.921.gf22659ad46-goog
