Re: [PATCH][RFC] NFS: Improving the access cache

[Steve Dickson <SteveD@redhat.com>]

Trond Myklebust wrote:
> 
> 
> Instead of having the field 'id', why don't you let the nfs_inode keep a
> small (hashed?) list of all the nfs_access_entry objects that refer to
> it? That would speed up searches for cached entries.
Actually I did look into having a pointer in the nfs_inode... but
what do you do when the second hashed list is needed. Meaning
P2(uid2) comes along and hashes to a different que. I guess
I thought it was a bit messy to keep overwriting the point in the
nfs_inode so I just kept everything in the hash table...

> I agree with Neil's assessment that we need a bound on the size of the
> cache. In fact, enforcing a bound is pretty much the raison d'être for a
> global table (by which I mean that if we don't need a bound, then we
> might as well cache everything in the nfs_inode).
Ok..

> How about rather changing that hash table into an LRU list, then adding
> a shrinker callback (using set_shrinker()) to allow the VM to free up
> entries when memory pressure dictates that it must?
Sounds interesting.. Just to be clear, by LRU list you mean use hlist
correct?

steved.

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