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mm: increase folio batch size

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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@linux.intel.com/

Link: https://lkml.kernel.org/r/20240315140823.2478146-1-willy@infradead.org
Fixes: 99fbb6bfc1 ("mm: make folios_put() the basis of release_pages()")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: Yujie Liu <yujie.liu@intel.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202403151058.7048f6a8-oliver.sang@intel.com
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2024-03-15 14:08:21 +00:00 committed by Andrew Morton
parent 7844c01472
commit 9cecde80aa
1 changed files with 2 additions and 2 deletions
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4
include/linux/pagevec.h
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@ -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;