Messages in this thread | | | Date | Thu, 8 Nov 2007 20:10:47 +0000 | Subject | Re: [patch 02/23] SLUB: Rename NUMA defrag_ratio to remote_node_defrag_ratio | From | (Mel Gorman) |
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On (08/11/07 10:56), Christoph Lameter didst pronounce: > On Thu, 8 Nov 2007, Mel Gorman wrote: > > > On (06/11/07 17:11), Christoph Lameter didst pronounce: > > > We need the defrag ratio for the non NUMA situation now. The NUMA defrag works > > > by allocating objects from partial slabs on remote nodes. Rename it to > > > > > > remote_node_defrag_ratio > > > > > > > I'm not too keen on the defrag name here largely because I cannot tell what > > it has to do with defragmention or ratios. It's really about working out > > when it is better to pack objects into a remote slab than reclaim objects > > from a local slab, right? It's also not clear what it is a ratio of what to > > what. I thought it might be clock cycles but that isn't very clear either. > > If we are renaming this can it be something like remote_packing_cost_limit ? > > In a NUMA situation we have a choice between > > 1. Allocating a page from the local node (which consumes more memory and > is advantageous performance wise. > > 2. Not allocating from the local node but see if any other node has > available partially allocated slabs. If we allocate from them then > we save memory and reduce the amount of partial slabs on the remote > node. Thus the fragmentation ratio is reduced. >
Ok, I get the logic somewhat now, thanks.
> > How about > > > > /* > > * When packing objects into slabs, it may become necessary to > > * reclaim objects on a local slab or allocate from a remote node. > > * The remote_packing_cost_limit is the maximum cost of remote > > * accesses that should be paid before it becomes worthwhile to > > * reclaim instead > > */ > > int remote_packing_cost_limit; > > > > ? > > That is not what this is about. And the functionality has been in SLUB > since the beginning. >
Yeah, my understanding of SLUB is crap. Sorry for the noise.
-- -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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