# using FS-cache with NFS?

## m27315

Is anybody using FS-cache with NFS?  I am experiencing some modest (~10-20%) performance degradation on the same hardware, between Gentoo and a RHEL5 (CentOS5.2) install, which has FS-cache built-in.  I tried following this HOWTO:

http://gentoo-wiki.com/HOWTO_FS-Cache

But, the latest patchset breaks with the latest gentoo kernel, and mm-sources will not even install (patch fail).

I'm just curious if anybody is using FS-cache with NFS on a modern kernel, or has this patch gone defunct in the Gentoo world.  Google is not turning up many results on Gentoo either...

It would be nice if this was included in the Gentoo kernel patch set.    :Rolling Eyes:   :Smile: 

Thanks!

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## m27315

I guess nobody is using FS-cache (or cache-fs) with modern kernels?   :Smile: 

I was afraid that this might be too much on the fringe, although I think this is accounting for a non-trivial speed bump I am seeing on a dual-boot RHEL5.2-Gentoo box.

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## m27315

This is now included in the 2.6.30 kernel, although it is deactivated by default:

```
File systems ---> Caches --->

                 <*> General filesystem local caching manager

                 [ ]   Gather statistical information on local caching

                 [ ]   Gather latency information on local caching

                 [ ]   Debug FS-Cache

                 <*>   Filesystem caching on files

                 [ ]     Debug CacheFiles 

                 [ ]     Gather latency information on CacheFiles
```

Unfortunately, my setup has changed, and I no longer have access to the same NFS setup.  Maybe somebody else can verify the performance impact of using this new module with NFS...

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## depontius

I've activated the kernel bits with 2.6.30, but haven't done the rest of the work.  Reading the (other, non-Gentoo) documentation I also see that you need a "good enough" level of nfs-utils and to get local-file (as opposed to local partition) caching running, you need some sort of daemon.  Have you actuallly got this running on Gentoo?  What did you do extra?

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## m27315

sorry, I started this thread last year, but I was blocked because I could not patch FS-CACHE into the kernel successfully.  Now, the kernel comes with FS-CACHE integrated, but now I no longer need it, nor can I use it.  My Gentoo box is no longer on an NFS network.  ... I will have to leave this up to you and others to test.  I only updated the thread in case somebody stumbled across it.

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## depontius

I've been running fscache with cachefilesd for some time now.  I notice no problems, nor can I really say if it's doing anything for me.  I supposed I should benchmark it one of these days.

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