[PATCHv9 0/6] iomap: Add support for per-block dirty state to improve write performance

Ritesh Harjani (IBM)
2023-06-10T11:39:23Z

Hello All,

Please find PATCHv9 which adds per-block dirty tracking to iomap.
As discussed earlier this is required to improve write performance and reduce
write amplification for cases where either blocksize is less than pagesize (such
as Power platform with 64k pagesize) or when we have a large folio (such as xfs
which currently supports large folio).

v7/v8 -> v9
============
1. Splitted the renaming & refactoring changes into different patchsets.
(Patch-1 & Patch-2)
2. Addressed review comments from everyone in v9.
3. Fixed a punch-out bug pointed out by Darrick in Patch-6.
4. Included iomap_ifs_calc_range() function suggested by Christoph in Patch-6.

Testing
=========
I have tested v9 on:-
- Power with 4k blocksize -g auto
- x86 with 1k and 1k_adv with -g auto
- arm64 with 4k blocksize and 64k pagesize with 4k quick
- also tested gfs2 with minimal local config (-O -b 1024 -p lock_nolock)
- unit tested failed punch-out operation with "-f" support to pwrite in
xfs_io.
I haven't observed any new testcase failures in any of my testing so far.

Thanks everyone for helping with reviews and suggestions.
Please do let me know if there are any further review comments on this one.

<Perf data copy paste from previous version>
=============================================
Performance testing of below fio workload reveals ~16x performance
improvement using nvme with XFS (4k blocksize) on Power (64K pagesize)
FIO reported write bw scores improved from around ~28 MBps to ~452 MBps.

1. <test_randwrite.fio>
[global]
ioengine=psync
rw=randwrite
overwrite=1
pre_read=1
direct=0
bs=4k
size=1G
dir=./
numjobs=8
fdatasync=1
runtime=60
iodepth=64
group_reporting=1

[fio-run]

2. Also our internal performance team reported that this patch improves
their database workload performance by around ~83% (with XFS on Power)

Ritesh Harjani (IBM) (6):
iomap: Rename iomap_page to iomap_folio_state and others
iomap: Drop ifs argument from iomap_set_range_uptodate()
iomap: Add some uptodate state handling helpers for ifs state bitmap
iomap: Refactor iomap_write_delalloc_punch() function out
iomap: Allocate ifs in ->write_begin() early
iomap: Add per-block dirty state tracking to improve performance

fs/gfs2/aops.c | 2 +-
fs/iomap/buffered-io.c | 394 +++++++++++++++++++++++++++++------------
fs/xfs/xfs_aops.c | 2 +-
fs/zonefs/file.c | 2 +-
include/linux/iomap.h | 1 +
5 files changed, 282 insertions(+), 119 deletions(-)

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2.40.1