[Gluster-users] help me, glusterfs 3.3 doen't support fopen-keep-cache?

[Brian Foster]

On 01/08/2013 09:49 AM, 符永涛 wrote:
> Dear gluster experts,
> 
> I search through glusterfs 3.3 source tree and can't find any fuse
> open option FOPEN_KEEP_CACHE related code. Does this mean that
> glusterfs 3.3 doen't support fuse keep cache feature? However I did
> find keep cache code in mainline. My question is:

It appears that keep cache support is not included in the 3.3 release.
You can build from the latest git repo to try it:

32ffb79f fuse/md-cache: add support for the 'fopen-keep-cache' mount option

> 1 does glusterfs 3.3 support page cache?

Page cache interaction is primarily a function of fuse. The current
behavior is that writes are synchronous to the fuse filesystem, reads
are potentially served from page cache, and file open operations
invalidate the entire mapping for a file.

The FOPEN_KEEP_CACHE fuse init option disables the latter behavior. In
turn, gluster detects whether changes have occurred in the file remotely
and nudges fuse to invalidate the file cache on-demand. There is also
upstream fuse work in progress to support writeback cache behavior[1].

> 2 if not what is the best practice to improve performance if a file is
> frequently accessed by read especially through random access fops.

I would suggest to experiment with the tunables in the io-cache
translator (xlators/performance/io-cache/src/io-cache.c), such as
priority, cache-timeout and cache-size.

> 3 does glusterfs 3.4 support page cache, if supported how to enable it
> through mount option?
> 

I would hope that it will at least include the keep cache support. Use
the fopen-keep-cache mount option on latest gluster to try it out.

Brian

[1] - http://comments.gmane.org/gmane.comp.file-systems.fuse.devel/12266

> Thank you very much.
>