Re: [patch -mm] cpusets: add memory_slab_hardwall flag

[Matt Mackall <mpm@selenic.com>]

On Sun, 2009-03-08 at 09:27 -0700, David Rientjes wrote:
> Adds a per-cpuset `memory_slab_hardwall' flag.
> 
> The slab allocator interface for determining whether an object is allowed
> is
> 
> 	int current_cpuset_object_allowed(int node, gfp_t flags)
> 
> This returns non-zero when the object is allowed, either because
> current's cpuset does not have memory_slab_hardwall enabled or because
> it allows allocation on the node.  Otherwise, it returns zero.
> 
> This interface is lockless because a task's cpuset can always be safely
> dereferenced atomically.
> 
> For slab, if the physical node id of the cpu cache is not from an
> allowable node, the allocation will fail.  If an allocation is targeted
> for a node that is not allowed, we allocate from an appropriate one
> instead of failing.
> 
> For slob, if the page from the slob list is not from an allowable node,
> we continue to scan for an appropriate slab.  If none can be used, a new
> slab is allocated.

Looks fine to me, if a little expensive. We'll be needing SLQB support
though.

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