[PATCH rfc 0/3] mm: allow more high-order pages stored on PCP lists

[Kefeng Wang <wangkefeng.wang@huawei.com>]

Both the file pages and anonymous pages support large folio, high-order
pages except PMD_ORDER will also be allocated frequently which could
increase the zone lock contention, allow high-order pages on pcp lists
could reduce the big zone lock contention, but as commit 44042b449872
("mm/page_alloc: allow high-order pages to be stored on the per-cpu lists")
pointed, it may not win in all the scenes, add a new control sysfs to
enable or disable specified high-order pages stored on PCP lists, the order
(PAGE_ALLOC_COSTLY_ORDER, PMD_ORDER) won't be stored on PCP list by default.

With perf lock tools, the lock contention from will-it-scale page_fault1
(with 90 tasks run 10s, hugepage-2048KB never, hugepage-64K always) show
below(only care about zone spinlock and pcp spinlock),

Without patches,
 contended   total wait     max wait     avg wait         type   caller
       713      4.64 ms     74.37 us      6.51 us     spinlock   __alloc_pages+0x23c

With patches,
 contended   total wait     max wait     avg wait         type   caller
         2     25.66 us     16.31 us     12.83 us     spinlock   rmqueue_pcplist+0x2b0

Similar results on shell8 from unixbench,

Without patches,
      4942    901.09 ms      1.31 ms    182.33 us     spinlock   __alloc_pages+0x23c	
      1556    298.76 ms      1.23 ms    192.01 us     spinlock   rmqueue_pcplist+0x2b0
       991    182.73 ms    879.80 us    184.39 us     spinlock   rmqueue_pcplist+0x2b0

With patches,
contended   total wait     max wait     avg wait         type   caller
       988    187.63 ms    855.18 us    189.91 us     spinlock   rmqueue_pcplist+0x2b0
       505     88.99 ms    793.27 us    176.21 us     spinlock   rmqueue_pcplist+0x2b0

The Benchmarks Score shows a little improvoment(0.28%) from shell8, but the
zone lock from __alloc_pages() disappeared.

Kefeng Wang (3):
  mm: prepare more high-order pages to be stored on the per-cpu lists
  mm: add control to allow specified high-order pages stored on PCP list
  mm: pcp: show each order page count

 Documentation/admin-guide/mm/transhuge.rst | 11 ++++
 include/linux/gfp.h                        |  1 +
 include/linux/huge_mm.h                    |  1 +
 include/linux/mmzone.h                     | 10 ++-
 include/linux/vmstat.h                     | 19 ++++++
 mm/Kconfig.debug                           |  8 +++
 mm/huge_memory.c                           | 74 ++++++++++++++++++++++
 mm/page_alloc.c                            | 30 +++++++--
 mm/vmstat.c                                | 16 +++++
 9 files changed, 164 insertions(+), 6 deletions(-)

-- 
2.27.0