The patch titled
Subject: mm: increase folio batch size
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-increase-folio-batch-size.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-increase-folio-batch-size.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: increase folio batch size
Date: Fri, 15 Mar 2024 14:08:21 +0000
On a 104 thread, 2 socket Skylake system, Intel report a 4.7% performance
reduction with will-it-scale page_fault2. This was due to reducing the
size of the batch from 32 to 15. Increasing the folio batch size from 15
to 31 gives a performance increase of 12.5% relative to the original, or
17.2% relative to the reduced performance commit.
The penalty of this commit is an additional 128 bytes of stack usage. Six
folio_batches are also allocated from percpu memory in cpu_fbatches so
that will be an additional 768 bytes of percpu memory (per CPU). Tim Chen
originally submitted a patch like this in 2020:
https://lore.kernel.org/linux-mm/d1cc9f12a8ad6c2a52cb600d93b06b064f2bbc57.1593205965.git.tim.c.chen@xxxxxxxxxxxxxxx/
Link: https://lkml.kernel.org/r/20240315140823.2478146-1-willy@xxxxxxxxxxxxx
Fixes: 99fbb6bfc16f ("mm: make folios_put() the basis of release_pages()")
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Tested-by: Yujie Liu <yujie.liu@xxxxxxxxx>
Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-lkp/202403151058.7048f6a8-oliver.sang@xxxxxxxxx
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/pagevec.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/include/linux/pagevec.h~mm-increase-folio-batch-size
+++ a/include/linux/pagevec.h
@@ -11,8 +11,8 @@
#include <linux/types.h>
-/* 15 pointers + header align the folio_batch structure to a power of two */
-#define PAGEVEC_SIZE 15
+/* 31 pointers + header align the folio_batch structure to a power of two */
+#define PAGEVEC_SIZE 31
struct folio;
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-increase-folio-batch-size.patch
