Hi Daan,
On 2023/8/31 17:48, Gao Xiang wrote:
Hi Daan,
On 2023/8/31 17:33, Daan De Meyer wrote:
Hi,
For hacking on systemd, we build disk images using mkosi, and use an erofs
filesystem for the /usr directory. When hacking on systemd, we would like to be
able to rebuild the disk image as fast as possible. One part of rebuilding the
image that takes a while is generating the erofs filesystem. I had a look at
the mkfs source code for erofs and noticed that in
write_uncompressed_file_from_fd(), there is no usage of FICLONERANGE or
copy_file_range() to speed up copying data from the filesystem to the erofs
filesystem. Would it be possible to use either of these to make copying data in
mkfs.erofs faster when the data does not need to be compressed?
Thanks for the email!
Yes, that is indeed useful, actually mmap I/Os can be used
to boost up write_uncompressed_file_from_fd () as well...
Actually many enhancements are limited by the current
development resource (multithreaded compression support might
be the top-1 priority for userspace side from end users),
but I have to resolve them one-by-one since EROFS is still a
quite young project compared to other approaches and beyond
the original targeted use cases (so most Android vendors won't
pay any attention to improvements that are not critically
important for their scenarios.)
I mostly focus on some kernel improvements since Google needs
us to support 16k page size + 4k EROFS block size. That is
currently my top thing to resolve first...
(quite limited by real world time...)
I already checked this part, it optimizes about 100ms for
the linux source code tree on my own developping machine.
Also after some profiling, there are some other stuffs that
needs to be optmized as well (e.g. optimize metadata write
counts)
Anyway, I'm about releasing erofs-utils v1.7. I tend to
resolve this in the next version and there are a lot
TODOs on my side.
Thanks,
Gao Xiang
Thanks,
Gao Xiang
Cheers,
Daan De Meyer
