PRAMFS: Persistent & Protected RAM Filesystem

[phoronix]

Phoronix: PRAMFS: Persistent & Protected RAM Filesystem

Patches on Sunday were published for the Linux kernel that provide PRAMFS, a persistent, non-volatile RAM-based file-system...

http://www.phoronix.com/vr.php?view=MTExNzM

[rxonda]

Is this new fs will boost up SSD rigs?

[Ferdinand]

I still think it is a good idea to have a read write cache in separate DDR3 memory. Use a small flywheel to power it in the case there is a power outage. You could populate it with low voltage 16GB memory of any speed. This would be a cache between the harddisk controllers and the cpu. Such a device would read and write at multiple GB's per second(bursts). This could slowly be synced with the harddisk.

I would like to hear your thoughts.

[huhn_m]

we already have that, it's called buffer cache.

I honestly don't see the benefit in this new fs. It is smaller than a normal buffered fs and less dynamic in what parts are kept in ram (because all of it is).

The only use, as michael wrote in his post, might be write-often embedded systems.

[Ferdinand]

we already have that, it's called buffer cache.

I honestly don't see the benefit in this new fs. It is smaller than a normal buffered fs and less dynamic in what parts are kept in ram (because all of it is).

The only use, as michael wrote in his post, might be write-often embedded systems.

AFAIK buffer cache empties on reboots and crashes. Also it doesn't cache writes. We have all seen what an ssd can do for your system. Now think what it would mean if disk reads or writes of less than 8GB would go at 8GB/s.

[huhn_m]

thats right. as long as you can cope with the small size.

Of course buffer cache is emptied on reboot as you wrote, so it will be faster directly after boot, but less adaptive than the caches.
But writes are also cached. Everything is basically cached and only written back when the kernel sees fit (according to the IO scheduler I think).

So it is basically a "pramfs" for the most or most recently used data.

It has pros and cons but I think the cons (size) outweigh the pros on a traditional system. Your Desktop is slow because it has to load tons of libs, when an application is started. This is better on SSDs where seek times are smaller. While these things would also benefit of the PRAMFS you would need potentially all libs in there and the binaries probably as well. On my small system thats 800MB already. Then you would need the local caches (of your browser, the thumbnail cache etc) to have the same effects as a ssd and so on. I don't think this is the approach for the desktop.