On Mon, Apr 15, 2024 at 8:12 PM Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> wrote:
>
> 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.
This is precisely something Baolin and I have discussed and intended
to implement[1],
but unfortunately, we haven't had the time to do so.
[1] https://lore.kernel.org/linux-mm/13c59ca8-baac-405e-8640-e693c78ef79a@xxxxxxx/T/#mecb0514ced830ac4df320113bedd7073bea9ab7a
>
> 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
>
>
