Re: [RFC PATCH 0/5] folio based filemap_map_pages()

["Yin, Fengwei" <fengwei.yin@intel.com>]

On 1/30/2023 8:54 PM, Yin Fengwei wrote:
> Current filemap_map_pages() still use page granularity
> even when the underneath folio is large folio. Making it
> use folio based granularity allows batched refcount,
> rmap and mm counter opertion. Which brings some level
> performance gain. This series tries to update
>    filemap_map_pages()
>    do_set_pte()
>    page_add_file_rmap()
> to bring batched refcount, rmap and mm counter in.
> 
> Patch 1 enabled the fault around for shared file page
>         write fault. As David suggested here:
> https://lore.kernel.org/linux-mm/e14b4e9a-612d-fc02-edc0-8f3b6bcf4148@redhat.com/
> 
> Patch 2 update filemap_map_pages() to do map based on
>         folio granularity and batched refcount update
> 
> Patch 3,4,5 Enable batched rmap and mm counter
> 
> Function testing:
>   - two days daily usage: boot to xfs GUI, kernel build, editor and browser
> 
> Performance testing:
>   - kernel build: no obvious performance impact
>   - micro benchmark: will-it-scale:page_fault3 (shared file write fault)
>     Patch 1 brings 3.75X performance gain
> 
>   - micro benchmark: will-it-scale:page_fault3 like but with file read fault
>     - Patch 2 brings about 2% performance gain (batched refcount)
>     - Patch 3,4,5 brings about 15% performance gain (batched rmap and mm counter)
> 
Forgot to mention: the base of the series is next-20230119.
> 
> Yin Fengwei (5):
>   mm: Enable fault around for shared file page fault
>   filemap: do file page mapping with folio granularity
>   rmap: add page_add_file_rmap_range()
>   mm: add do_set_pte_entry()
>   filemap: batched update mm counter,rmap when map file folio
> 
>  include/linux/mm.h   |   2 +
>  include/linux/rmap.h |   2 +
>  mm/filemap.c         | 106 +++++++++++++++++++++++++++++--------------
>  mm/memory.c          |  25 +++++++++-
>  mm/rmap.c            |  70 +++++++++++++++++-----------
>  5 files changed, 143 insertions(+), 62 deletions(-)
>