Major Rewrite Of Linux's FS-Cache / CacheFiles So It's Smaller & Simpler

[tuxd3v]

Thanks to David Howells for his work. If FS-Cache is for network file systems, the rewrite will benefit mostly servers? But rewriting CacheFiles might also benefit desktops? I'm genuinely curious.

CacheFiles files should benefit for cache from local filesystems..so it should theoretically also benefit desktop's,
The amount of the benefit its something that we don't know, it will depend from case to case, considering each use case,
But this, if CacheFiles is what I am thinking about, I am not sure..

Maybe someone more educated on the matter can elaborate more about the subject..

[cl333r]

Hopefully this leads to the fs dentry cache not eating so much RAM. We had a file system where every time we did an rsync it would use 32GB of RAM and not give it up until we did a manual flush. For long term file storage systems where a file may only be really accessed once a year it need to learn to let go.

Not an expert on any on this but I was wondering if there should be a totally new POSIX 2.0 (like we did with Vulkan vs GL, or Wayland vs X11), it shows its age by dealing with its old naming conventions from the 1980's and little issues like that. I for one don't like that when you list files in any folder the system also lists "." and "..", so 99.9% of code has to test each file name against these names:

for (...) {
if (d->d_name != "." && d->d_name != "..")
// go on
}

[Alexmitter]

Can it be updated to allow zfs integration. Its ridiculous that zfs occupies "in-use" memory.

If something is ridiculous then it is using zfs on Linux.

[waxhead]

No, this is not how things work.

Finally someone that knows how it works. Not used memory is wasted memory and the more of it that is used for cache the better...

[flower]

I would love to have a way to tell the kernel "this is a process that runs rarely please don't cache after it's done"

Would help with backups and very big greps

[down1]

I would love to have a way to tell the kernel "this is a process that runs rarely please don't cache after it's done"

Would help with backups and very big greps

Correct me if I'm wrong, but are you looking for this https://github.com/Feh/nocache

[flower]

Correct me if I'm wrong, but are you looking for this https://github.com/Feh/nocache

This looks perfect! Thank you!
I will definitely try it

[sinepgib]

Finally someone that knows how it works. Not used memory is wasted memory and the more of it that is used for cache the better...

While this is entirely true, it is also true that keeping pages you can determine will not be needed again is also a waste of memory. Keep in mind your disk is much bigger than you physical memory. This means there will probably be filesystem pages competing for that memory at some point, you want to reduce those conflicts if you can do it easily.
That's where tools like down1 shared come in handy.

[kenjo]

Supposedly this cache would have to return to the pool of free memory, after a while, but it doesn't or if it returns returns very few..

No. If you use the command line tool "free" you will see that it has free memory and available memory. the important one is the available number and not the free one. Free memory is just memory that is currently unused for anything. available is the memory that can be used/allocated by a program.

[waxhead]

While this is entirely true, it is also true that keeping pages you can determine will not be needed again is also a waste of memory. Keep in mind your disk is much bigger than you physical memory. This means there will probably be filesystem pages competing for that memory at some point, you want to reduce those conflicts if you can do it easily.
That's where tools like down1 shared come in handy.

Absolutely, but personally I would prefer putting a program that benefits from nocache to a cgroup and set some memory limits (easy with systemd).