Messages in this thread Patch in this message | | | Date | Mon, 28 May 2018 19:40:25 -0700 | Subject | [PATCH] mm: convert scan_control.priority int => byte | From | Greg Thelen <> |
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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@google.com> --- 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
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