[PATCH] Zone reclaim: resurrect may_swap
Zone reclaim has a huge impact on NUMA performance (f.e. our maximum
throughput with XFS is raised from 4GB to 6GB/sec / page cache contamination
of numa nodes destroys locality if one just does a large copy operation which
results in performance dropping for good until reboot).
This patch:
Resurrect may_swap in struct scan_control
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 827bf67..e5117b6 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -71,6 +71,9 @@
int may_writepage;
+ /* Can pages be swapped as part of reclaim? */
+ int may_swap;
+
/* This context's SWAP_CLUSTER_MAX. If freeing memory for
* suspend, we effectively ignore SWAP_CLUSTER_MAX.
* In this context, it doesn't matter that we scan the
@@ -458,6 +461,8 @@
* Try to allocate it some swap space here.
*/
if (PageAnon(page) && !PageSwapCache(page)) {
+ if (!sc->may_swap)
+ goto keep_locked;
if (!add_to_swap(page, GFP_ATOMIC))
goto activate_locked;
}
@@ -1166,6 +1171,7 @@
sc.gfp_mask = gfp_mask;
sc.may_writepage = 0;
+ sc.may_swap = 1;
inc_page_state(allocstall);
@@ -1268,6 +1274,7 @@
total_reclaimed = 0;
sc.gfp_mask = GFP_KERNEL;
sc.may_writepage = 0;
+ sc.may_swap = 1;
sc.nr_mapped = read_page_state(nr_mapped);
inc_page_state(pageoutrun);