On Wed, Mar 27, 2024 at 09:54:01AM +0100, Vlastimil Babka wrote:
> > @@ -1314,10 +1349,10 @@ static inline void expand(struct zone *zone, struct page *page,
> > * Corresponding page table entries will not be touched,
> > * pages will stay not present in virtual address space
> > */
> > - if (set_page_guard(zone, &page[size], high, migratetype))
> > + if (set_page_guard(zone, &page[size], high))
> > continue;
> >
> > - add_to_free_list(&page[size], zone, high, migratetype);
> > + add_to_free_list(&page[size], zone, high, migratetype, false);
>
> This is account_freepages() in the hot loop, what if we instead used
> __add_to_free_list(), sum up nr_pages and called account_freepages() once
> outside of the loop?
How about this on top of the series? Could be folded into
mm-page_alloc-consolidate-free-page-accounting, but for credit and
bisectability (just in case) I think stand-alone makes sense.
---
>From 361f5df28183d85c7718fe0b579438d3d58777be Mon Sep 17 00:00:00 2001
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Date: Wed, 27 Mar 2024 12:29:25 -0400
Subject: [PATCH 3/3] mm: page_alloc: batch vmstat updates in expand()
expand() currently updates vmstat for every subpage. This is
unnecessary, since they're all of the same zone and migratetype.
Count added pages locally, then do a single vmstat update.
Suggested-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
mm/page_alloc.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8987e8869f6d..13fe5c612fbe 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1341,6 +1341,7 @@ static inline void expand(struct zone *zone, struct page *page,
int low, int high, int migratetype)
{
unsigned long size = 1 << high;
+ unsigned long nr_added = 0;
while (high > low) {
high--;
@@ -1356,9 +1357,11 @@ static inline void expand(struct zone *zone, struct page *page,
if (set_page_guard(zone, &page[size], high))
continue;
- add_to_free_list(&page[size], zone, high, migratetype, false);
+ __add_to_free_list(&page[size], zone, high, migratetype, false);
set_buddy_order(&page[size], high);
+ nr_added += size;
}
+ account_freepages(zone, nr_added, migratetype);
}
static void check_new_page_bad(struct page *page)
--
2.44.0
