Messages in this thread | | | Date | Thu, 28 Oct 2004 08:40:04 -0700 | From | "Martin J. Bligh" <> | Subject | Re: NUMA node swapping V3 |
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> Changes from V2: better documentation, fix missing #ifdef > > In a NUMA systems single nodes may run out of memory. This may occur even > by only reading from files which will clutter node memory with cached > pages from the file. > > However, as long as the system as a whole does have enough memory > available, kswapd is not run at all. This means that a process allocating > memory and running on a node that has no memory left, will get memory > allocated from other nodes which is inefficient to handle. It would be > better if kswapd would throw out some pages (maybe some of the cached > pages from files that have only once been read) to reclaim memory in the > node. > > The following patch checks the memory usage after each allocation in a > zone. If the allocation in a zone falls below a certain minimum, kswapd is > started for that zone alone. > > The minimum may be controlled through /proc/sys/vm/node_swap which is set > to zero by default and thus is off. > > If it is set for example to 100 then kswapd will be run on > a zone/node if less than 10% of pages are available after an allocation.
I thought even the SGI people were saying this wouldn't actually help you, due to some workload issues?
M.
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