Messages in this thread |  | | | Date | Mon, 8 Feb 2010 11:40:38 -0600 (CST) | | From | Christoph Lameter <> | | Subject | Re: inodes: Support generic defragmentation |
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On Mon, 8 Feb 2010, Nick Piggin wrote:
> > > After that, LRU on slabs should be fairly easy. Slab could provide a > > > private per-slab pointer for example that is managed by the caller. > > > Subsystem can then call into slab to find the objects. > > > > Sure with some minor changes we could have a call that is giving you the > > list of neighboring objects in a slab, while locking it? Then you can look > > at the objects and decide which ones can be tossed and then do another > > call to release the objects and unlock the slab. > > Yep. Well... you may not even need to ask slab layer to lock the > slab. Provided that the subsystem is locking out changes. It could > possibly be helpful to have a call to lock and unlock the slab, > although usage of such an API would have to be very careful.
True, if you are holding a reference to an object in a slab page and there is a guarantee that the object is not going away then the slab is already effectively pinned.
So we just need a call that returns
1. The number of allocated objects in a slab page 2. The total possible number of objects 3. A list of pointers to the objects
?
Then reclaim could make a decision if you want these objects to be reclaimed.
Such a function could actually be a much less code than the current patchset and would also be easy to do for SLAB/SLOB.
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