[PATCH v2 4/4] erofs: use buffered I/O for file-backed mounts by default

[Chao Yu]

On 2024/12/12 21:43, Gao Xiang wrote:
> For many use cases (e.g. container images are just fetched from remote),
> performance will be impacted if underlay page cache is up-to-date but
> direct i/o flushes dirty pages first.
> 
> Instead, let's use buffered I/O by default to keep in sync with loop
> devices and add a (re)mount option to explicitly enable direct I/O
> if supported by the underlying files.
> 
> The container startup time is improved as below:
>                                       unpack        1st run  non-1st runs
> EROFS snapshotter buffered I/O file  4.586404265s  0.308s   0.198s
> EROFS snapshotter direct I/O file    4.581742849s  2.238s   0.222s
> EROFS snapshotter loop               4.596023152s  0.346s   0.201s
> Overlayfs snapshotter                5.382851037s  0.206s   0.214s
> 
> Fixes: fb176750266a ("erofs: add file-backed mount support")
> Cc: Derek McGowan <derek at mcg.dev>
> Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>

Reviewed-by: Chao Yu <chao at kernel.org>

Thanks,