Messages in this thread | | | Date | Wed, 4 Aug 1999 22:50:05 +0200 | From | Frank van Maarseveen <> | Subject | NFS client caching problems in 2.2.x (and proposal) |
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I've been following some of the changes in NFS FS in 2.2.6-ac3, 2.2.10-ac?? and the 2.2.11-pre patches and it appears that a more aggressive form of caching has been implemented. Unfortunately only 2.2.6-ac3 has an acceptable behavior (for my particular situation) even though it has obvious bugs (reading the source and looking at the OOPSes in /var/log/messages). The problem is that if one mounts from the Internet one probably wants aggressive caching but not in every situation: it must be possible to _disable_ these optimizations.
The heuristics implemented in the 2.2.10-ac11 and beyond are hard coded and that is a _real_ problem:
fs/nfs/dir.c:nfs_neg_need_reval() fs/nfs/dir.c:nfs_dentry_force_reval()
Propose:
/proc/fs/nfs/<mount-point>/acdirmin /acdirmax /acregmin /acregmax /nfs_neg_need_reval (?) /nfs_dentry_force_reval (?)
A lot of NFS mount options can be made switchable this way without having to remount the file system or to extend all the mount(2) related stuff or figuring out the magic recipe for the heuristic which satifies everyone. This recipe probably doesn't exist because different situations demand different caching policies.
-- Frank
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