[0/2] Improve the tmpfs large folio read performance

Message

Baolin Wang Oct. 16, 2024, 10:09 a.m. UTC

The tmpfs has already supported the PMD-sized large folios, but the tmpfs
read operation still performs copying at the PAGE SIZE granularity, which
is not perfect. This patch changes to copy data at the folio granularity,
which can improve the read performance.

Use 'fio bs=64k' to read a 1G tmpfs file populated with 2M THPs, and I can
see about 20% performance improvement, and no regression with bs=4k. I
also did some functional test with the xfstests suite, and I did not find
any regressions with the following xfstests config.
  FSTYP=tmpfs
  export TEST_DIR=/mnt/tempfs_mnt
  export TEST_DEV=/mnt/tempfs_mnt
  export SCRATCH_MNT=/mnt/scratchdir
  export SCRATCH_DEV=/mnt/scratchdir

Baolin Wang (2):
  mm: shmem: update iocb->ki_pos directly to simplify tmpfs read logic
  mm: shmem: improve the tmpfs large folio read performance

 mm/shmem.c | 54 ++++++++++++++++++++++--------------------------------
 1 file changed, 22 insertions(+), 32 deletions(-)

Comments

Kefeng Wang Oct. 16, 2024, 11:47 a.m. UTC | #1

On 2024/10/16 18:09, Baolin Wang wrote:
> The tmpfs has already supported the PMD-sized large folios, but the tmpfs
> read operation still performs copying at the PAGE SIZE granularity, which
> is not perfect. This patch changes to copy data at the folio granularity,
> which can improve the read performance.
> 
> Use 'fio bs=64k' to read a 1G tmpfs file populated with 2M THPs, and I can
> see about 20% performance improvement, and no regression with bs=4k. I
> also did some functional test with the xfstests suite, and I did not find
> any regressions with the following xfstests config.
>    FSTYP=tmpfs
>    export TEST_DIR=/mnt/tempfs_mnt
>    export TEST_DEV=/mnt/tempfs_mnt
>    export SCRATCH_MNT=/mnt/scratchdir
>    export SCRATCH_DEV=/mnt/scratchdir
> 

Oh，we make same changes, my bonnie test(./bonnie -d /tmp -s 1024) see
similar improvement(19.2% with huge=always) with out inner changes :)

> Baolin Wang (2):
>    mm: shmem: update iocb->ki_pos directly to simplify tmpfs read logic
>    mm: shmem: improve the tmpfs large folio read performance
> 
>   mm/shmem.c | 54 ++++++++++++++++++++++--------------------------------
>   1 file changed, 22 insertions(+), 32 deletions(-)
>