在 2023/6/21 18:00, Kefeng Wang 写道:
Hi Liuq,
On 2023/6/21 17:20, liuq wrote:
The current calculation of min_free_kbytes only uses ZONE_DMA and
ZONE_NORMAL pages,but the ZONE_MOVABLE zone->_watermark[WMARK_MIN]
will also divide part of min_free_kbytes.This will cause the min
watermark of ZONE_NORMAL to be too small in the presence of ZONE_MOVEABLE.
__GFP_HIGH and PF_MEMALLOC allocations usually don't need movable
zone pages, so just like ZONE_HIGHMEM, cap pages_min to a small
value in __setup_per_zone_wmarks.
On my testing machine with 16GB of memory (transparent hugepage is
turned off by default, and movablecore=12G is configured)
The following is a comparative test data of watermark_min
no patch add patch
ZONE_DMA 1 8
ZONE_DMA32 151 709
ZONE_NORMAL 233 1113
ZONE_MOVABLE 1434 128
min_free_kbytes 7288 7326
We see this issue and do the same change[1], and we add a per zone watermark configuration too, but both of them is not accepted,
let's add Mel and wupeng to see more comments.
[1]https://lore.kernel.org/linux-mm/20220905032858.1462927-1-mawupeng1@xxxxxxxxxx/
Hi wupeng,
Thank you for your reply. Actually, in my version 1, in the presence of ZONE_MOVABLE,
the calculation of min_free_kbytes can be improved when the ZONE_MOVABLE pages were added to the lowmem_kbytes.
However, whether the value of watermark_min should be maintained at high level is unclear.
https://lore.kernel.org/all/20230609032552.218010-1-liuq131@xxxxxxxxxxxxxxx/#r
Best Regards
liuq
Signed-off-by: liuq <liuq131@xxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 47421bedc12b..590ed8725e09 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6362,9 +6362,9 @@ static void __setup_per_zone_wmarks(void)
struct zone *zone;
unsigned long flags;
- /* Calculate total number of !ZONE_HIGHMEM pages */
+ /* Calculate total number of !ZONE_HIGHMEM and !ZONE_MOVABLE pages */
for_each_zone(zone) {
- if (!is_highmem(zone))
+ if (!is_highmem(zone) && zone_idx(zone) != ZONE_MOVABLE)
lowmem_pages += zone_managed_pages(zone);
}
@@ -6374,15 +6374,15 @@ static void __setup_per_zone_wmarks(void)
spin_lock_irqsave(&zone->lock, flags);
tmp = (u64)pages_min * zone_managed_pages(zone);
do_div(tmp, lowmem_pages);
- if (is_highmem(zone)) {
+ if (is_highmem(zone) || zone_idx(zone) == ZONE_MOVABLE) {
/*
* __GFP_HIGH and PF_MEMALLOC allocations usually don't
- * need highmem pages, so cap pages_min to a small
- * value here.
+ * need highmem and movable zones pages, so cap pages_min
+ * to a small value here.
*
* The WMARK_HIGH-WMARK_LOW and (WMARK_LOW-WMARK_MIN)
* deltas control async page reclaim, and so should
- * not be capped for highmem.
+ * not be capped for highmem and movable zones.
*/
unsigned long min_pages;
