From: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
Please be notice bellowing typical scenario that commit 168676649 introduce,
that is, 12MB free cma pages 'help' GFP_MOVABLE to keep draining/fragmenting
U&R page blocks until they shrink to 12MB without enter slowpath which against
current reclaiming policy. This commit change the criteria from hard coded '1/2'
to watermark check which leave U&R free pages stay around WMARK_LOW when being
fallback.
DMA32 free:25900kB boost:0kB min:4176kB low:25856kB high:29516kB
Signed-off-by: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
---
mm/page_alloc.c | 40 ++++++++++++++++++++++++++++++++++++----
1 file changed, 36 insertions(+), 4 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0745aed..97768fe 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3071,6 +3071,39 @@ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
}
+#ifdef CONFIG_CMA
+static bool __if_use_cma_first(struct zone *zone, unsigned int order, unsigned int alloc_flags)
+{
+ unsigned long cma_proportion = 0;
+ unsigned long cma_free_proportion = 0;
+ unsigned long watermark = 0;
+ unsigned long wm_fact[ALLOC_WMARK_MASK] = {1, 1, 2};
+ long count = 0;
+ bool cma_first = false;
+
+ watermark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK);
+ /*check if GFP_MOVABLE pass previous watermark check via the help of CMA*/
+ if (!zone_watermark_ok(zone, order, watermark, 0, alloc_flags & (~ALLOC_CMA)))
+ {
+ alloc_flags &= ALLOC_WMARK_MASK;
+ /* WMARK_LOW failed lead to using cma first, this helps U&R stay
+ * around low when being drained by GFP_MOVABLE
+ */
+ if (alloc_flags <= ALLOC_WMARK_LOW)
+ cma_first = true;
+ /*check proportion for WMARK_HIGH*/
+ else {
+ count = atomic_long_read(&zone->managed_pages);
+ cma_proportion = zone->cma_pages * 100 / count;
+ cma_free_proportion = zone_page_state(zone, NR_FREE_CMA_PAGES) * 100
+ / zone_page_state(zone, NR_FREE_PAGES);
+ cma_first = (cma_free_proportion >= wm_fact[alloc_flags] * cma_proportion
+ || cma_free_proportion >= 50);
+ }
+ }
+ return cma_first;
+}
+#endif
/*
* Do the hard work of removing an element from the buddy allocator.
* Call me with the zone->lock already held.
@@ -3087,10 +3120,9 @@ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac,
* allocating from CMA when over half of the zone's free memory
* is in the CMA area.
*/
- if (alloc_flags & ALLOC_CMA &&
- zone_page_state(zone, NR_FREE_CMA_PAGES) >
- zone_page_state(zone, NR_FREE_PAGES) / 2) {
- page = __rmqueue_cma_fallback(zone, order);
+ if (migratetype == MIGRATE_MOVABLE) {
+ bool cma_first = __if_use_cma_first(zone, order, alloc_flags);
+ page = cma_first ? __rmqueue_cma_fallback(zone, order) : NULL;
if (page)
return page;
}
--
1.9.1
