[ Upstream commit 6422cde1b0 ]
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 give a try to use
direct I/O if supported by the underlying files.
The container startup time is improved as below:
[workload] docker.io/library/workpress:latest
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: fb17675026 ("erofs: add file-backed mount support")
Cc: Derek McGowan <derek@mcg.dev>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20241212134336.2059899-1-hsiangkao@linux.alibaba.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
3042448109