Christoph Hellwig [off-list ref] 于2025年8月25日周一 17:21写道：

On Mon, Aug 25, 2025 at 04:51:27PM +0800, Fengnan Chang wrote:

quoted

No restrictions for now, I think we can enable this by default.
Maybe better solution is modify in bio.c?  Let me do some test first.

Any kind of numbers you see where this makes a different, including
the workloads would also be very valuable here.

I'm test random direct read performance on  io_uring+ext4, and try
compare to io_uring+ raw blkdev,  io_uring+ext4 is quite poor, I'm try to
improve this, I found ext4 is quite different with blkdev when run
bio_alloc_bioset. It's beacuse blkdev ext4  use percpu bio cache, but ext4
path not. So I make this modify.
My test command is:
/fio/t/io_uring -p0 -d128 -b4096 -s1 -c1 -F1 -B1 -R1 -X1 -n1 -P1 -t0
/data01/testfile
Without this patch:
BW is 1950MB
with this patch
BW is 2001MB.