Messages in this thread | | | Subject | Re: [PATCH 0/5] make slab gfp fair | From | Peter Zijlstra <> | Date | Thu, 17 May 2007 23:26:49 +0200 |
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On Thu, 2007-05-17 at 12:24 -0700, Christoph Lameter wrote: > On Thu, 17 May 2007, Peter Zijlstra wrote: > > > The proposed patch doesn't change how the kernel functions at this > > point; it just enforces an existing rule better. > > Well I'd say it controls the allocation failures. And that only works if > one can consider the system having a single zone. > > Lets say the system has two cpusets A and B. A allocs from node 1 and B > allocs from node 2. Two processes one in A and one in B run on the same > processor. > > Node 1 gets very low in memory so your patch kicks in and sets up the > global memory emergency situation with the reserve slab. > > Now the process in B will either fail although it has plenty of memory on > node 2. > > Or it may just clear the emergency slab and then the next critical alloc > of the process in A that is low on memory will fail.
The way I read the cpuset page allocator, it will only respect the cpuset if there is memory aplenty. Otherwise it will grab whatever. So still, it will only ever use ALLOC_NO_WATERMARKS if the whole system is in distress.
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