Re: [PATCH v2] f2fs: skip direct I/O iostat context when disabled

[Chao Yu]

On 6/16/26 11:06, Wenjie Qi wrote:
> F2FS iostat is optional and is disabled by default.  Direct I/O still
> allocates and binds a bio_iostat_ctx, updates the submit timestamp, and
> replaces bi_end_io for every DIO bio even when sbi->iostat_enable is
> false.
> 
> The byte accounting calls do not need an extra guard because
> f2fs_update_iostat() already checks sbi->iostat_enable.  Only skip the
> DIO bio context setup when iostat is disabled.  If iostat is enabled
> through sysfs before submission, the existing context allocation and
> latency accounting path is still used.
> 
> QEMU benchmark on a 1GiB F2FS virtio-blk image, with iostat_enable=0,
> 4KiB O_DIRECT I/O over a 64MiB file, 50000 iterations per run:
> 
>                          baseline     patched
>   direct_read median    65264.50 ns  55470.95 ns
>   direct_read recheck   65553.75 ns  55470.95 ns
>   direct_write median   68054.62 ns  56309.44 ns
>   direct_write recheck  66873.51 ns  56309.44 ns
> 
> Signed-off-by: Wenjie Qi <qiwenjie@xxxxxxxxxx>

Reviewed-by: Chao Yu <chao@xxxxxxxxxx>

Thanks,