On Sat, May 15, 2010 at 01:08:17PM -0400, Ed Tomlinson wrote: > On Friday 14 May 2010 16:36:03 Andi Kleen wrote: > > Christoph Lameter <cl@xxxxxxxxx> writes: > > > > > Would it also be possible to add some defragmentation logic when you > > > revise the shrinkers? Here is a prototype patch that would allow you to > > > determine the other objects sitting in the same page as a given object. > > > > > > With that I hope that you have enough information to determine if its > > > worth to evict the other objects as well to reclaim the slab page. > > > > I like the idea, it would be useful for the hwpoison code too, > > when it tries to clean a page. > > If this is done generally we probably want to retune the 'pressure' put on the slab. The > whole reason for the callbacks was to keep the 'pressure on the slab proportional to the > memory pressure (scan rate). I don't see that defrag based reclaim changes the concept of pressure at all. As long as reclaim follows the nr_to_scan guideline, then it doesn't matter if we do reclaim from the LRU or reclaim from a list provided by the slab cache.... FWIW, one thing that would be necessary, I think, is to avoid defrag until a certain level of fragmentation has occurred - we should do LRU-based reclaim as much as possible, and only trigger defrag-style reclaim once we hit a trigger (e.g. once the slab is 25% partial pages). Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>