Hi:
squashfs+lz4 / aufs to speed up my laptop
Squashfs proves its usefulness especially in combination with aufs or overlayfs; I suppose that this combination will become more popular with the spreading of overlayfs (e.g. to save disk space etc.) For users with such a combination, it is especially important to get a fast (re)compression of huge directories. The speed of LZ4 for compression in such a setting is really incredible. Just for orientation for myself, I made a list of times/sizes on some machines I had access to: https://github.com/vaeth/squashmount/blob/master/compress.txt (I do not claim that this is a scientific benchmark - just a straightforward average over several runs). The results for the kernel source and libreoffice are really unbelievable, but I repeated them several times (and, as you can see, for the kernel sources on different machines).
From the user perspective, it is mainly important that
the files compressed in this way can be read by the kernel - the decompression speed is here secondary, so I made no comparison for this case, although lz4 is known to be very fast also for decompression. I would really like to see lz4 support included in the squashfs kernel driver. I cannot imagine any negative consequences, especially since squashfs and lz4 are in the kernel, anyway. Sincerely Martin Väth
