On 21/01/2023 14:50, Christoph Hellwig wrote:
To prepare for pending changes drop the optimization to only look up
csums once per bio that is submitted from the iomap layer. In the
short run this does cause additional lookups for fragmented direct
reads, but later in the series, the bio based lookup will be used on
the entire bio submitted from iomap, restoring the old behavior
in common code.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Anand Jain <anand.jain@xxxxxxxxxx>
I was curious about the commit message.
I ran fio to test the performance before and after the change.
The results were similar.
fio --group_reporting=1 --directory /mnt/test --name dioread --direct=1
--size=1g --rw=read --runtime=60 --iodepth=1024 --nrfiles=16 --numjobs=16
before this patch
READ: bw=8208KiB/s (8405kB/s), 8208KiB/s-8208KiB/s (8405kB/s-8405kB/s),
io=481MiB (504MB), run=60017-60017msec
after this patch
READ: bw=8353KiB/s (8554kB/s), 8353KiB/s-8353KiB/s (8554kB/s-8554kB/s),
io=490MiB (513MB), run=60013-60013msec
