On Fri, 04 Apr 2008 11:00:34 -0400 Lee Schermerhorn wrote:
> PATCH 08/15 Mem Policy: rework mempolicy reference counting [yet again]
>
> Against: 2.6.25-rc8-mm1
>
> Documentation/vm/numa_memory_policy.txt | 68 ++++++++++++++
>
> Index: linux-2.6.25-rc8-mm1/Documentation/vm/numa_memory_policy.txt
> ===================================================================
> --- linux-2.6.25-rc8-mm1.orig/Documentation/vm/numa_memory_policy.txt 2008-04-02 17:47:15.000000000 -0400
> +++ linux-2.6.25-rc8-mm1/Documentation/vm/numa_memory_policy.txt 2008-04-02 17:47:26.000000000 -0400
> @@ -311,6 +311,74 @@ Components of Memory Policies
> MPOL_PREFERRED policies that were created with an empty nodemask
> (local allocation).
...
> + Because of this extra reference counting, and because we must lookup
> + shared policies in a tree structure under spinlock, shared policies are
> + more expensive to use in the page allocation path. This is expecially
especially
> + true for shared policies on shared memory regions shared by tasks running
> + on different NUMA nodes. This extra overhead can be avoided by always
> + falling back to task or system default policy for shared memory regions,
> + or by prefaulting the entire shared memory region into memory and locking
> + it down. However, this might not be appropriate for all applications.
> +
> MEMORY POLICY APIs
>
> Linux supports 3 system calls for controlling memory policy. These APIS
---
~Randy
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