Re: fio version change gives different throughput results

[Vincent Fu <vincentfu@gmail.com>]

On 3/6/24 04:44, Thomas Weber wrote:

<snip>

> 
> Thank you. I noticed that fix as well in the fio changelog.
>  From the description it seems to affect only non-sequential IO.
> However I saw huge throughput degradations for both rw=rw and
> rw=randrw.
> 
> Do you think this is related to that bug fix too?
> 
> [smallstuff-seq-slow]
> rw=rw
> nrfiles=1000
> openfiles=25
> filesize=1k-1m
> bssplit=4k/20:128k/80
> rwmixread=60
> 
> [smallstuff-rand-slow]
> rw=randrw
> nrfiles=1000
> openfiles=25
> filesize=1k-1m
> bssplit=4k/50:8k/25:64k/25
> rwmixread=75
> 

The patch description mentions file_service_type != sequential but makes 
no comment about whether offsets are chosen randomly or sequentially. In 
fact the example job in the patch description chooses offsets randomly.

I tried your smallstuff-seq-slow job and found the following:

fio-3.25+ [1]:----- 424 MiB/s read, 384 MiB/s write
fio-3.36:---------- 384 MiB/s read, 347 MiB/s write
fio-3.36-97-g9b699: 517 MiB/s read, 467 MiB/s write

[1] fio-3.25 needs 382975557e632efb506836bc1709789e615c9094 to build 
with recent kernels

If you are able to reliably reproduce the problem I suggest that you run 
git bisect to identify the commit responsible for the difference you 
have observed.

Vincent