FS-Cache Rewritten But Even Its Developers Are Hesitant About Landing It For Linux 5.9

[phoronix]

Phoronix: FS-Cache Rewritten But Even Its Developers Are Hesitant About Landing It For Linux 5.9

FS-Cache provides the Linux kernel with a general purpose cache for network file-systems like NFS and AFS but also other special use-cases like ISO9660 file-systems. FS-Cache has been rewritten for better performance and reliability, among other benefits, and while it has been sent in as a pull request for Linux 5.9 even its own developers provide some caution over landing it this cycle...

http://www.phoronix.com/scan.php?page=news_item&px=FS-Cache-Rewrite-For-Linux-5.9

[skerit]

There's been a bug in FS-Cache since a few versions that cause a kernel panic when doing a read() shortly after a write(), so it's unusable anyway at the moment.

[cl333r]

A rewrite, why not in Rust?

[Pentarctagon]

A rewrite, why not in Rust?

Probably because Rust has only just begun to be considered for whether or not it's appropriate for the kernel.

[skeevy420]

A rewrite, why not in Rust?

I'm beginning to not be able to tell if "Rust Rewrite Posts" are serious or joking.

I don't know if that's a good or a bad thing.

[cl333r]

I'm beginning to not be able to tell if "Rust Rewrite Posts" are serious or joking.

I don't know if that's a good or a bad thing.

Why not, Rust is fast and so it would make Linux faster, some day one could incorporate Rust's WebRender engine into Linux to make it even faster and take full advantage of Vulkan, no?

[skeevy420]

Why not, Rust is fast and so it would make Linux faster, some day one could incorporate Rust's WebRender engine into Linux to make it even faster and take full advantage of Vulkan, no?

I totally agree in regards to the merits of Rust...just hard to tell if these posts are serious or not.

[djkork]

There's been a bug in FS-Cache since a few versions that cause a kernel panic when doing a read() shortly after a write(), so it's unusable anyway at the moment.

There's a patch proposal from Xiaoli Feng that works like a charm. Proposed on Kernel.org Bugzilla – Bug 208883.

I've tested proposed patch on every released kernel from 5.8.0 rc7 to 5.9.1 Working without problems in all of them.

Using FS-CACHE cachefilesd and NFS v3 and NFSv4. Using SSD as cache filesystem i've measured 384 MB/s NFS read speed, and cached pages are persistent between reboots (unless invalidated by nfs remote share).

type nfs4 (rw,relatime,vers=4.2,rsize=524288,wsize=524288,na mlen=255,
hard,proto=tcp,timeo=14,retrans=2,sec=sys,fsc,local_lock=none,_netdev)


With this patch, FS-CACHE is usable and works like a charm!!