New feat: readahead like option

[niziak]

I'm building remotely huge images to flash. Remote images are xz compressed with maximum compression level to reduce time needed to download it to my location.

I'm using ratarmount to wrap vendor specific flashing script and add support for .xz compressed directory.

I noticed that vendor flashing tool is not well optimised: it reads chunk of image , then it transfer it over USB and waits for target until chunk is flashed. So during this wait time it will be nice that remote .xz file (over NFS) will be read into page cache for further use.

Currently I'm spawning vmtouch into background to achieve this feature.

[mxmlnkn]

It sounds like this https://github.com/mxmlnkn/mfusepy/issues/4 issue might coincidentally apply to your use case. It might be possible to also do some prefetching in the XZ decompressor, though.