Re: [patch 12/26] SLUB: Slab defragmentation core

[Nish Aravamudan]

On 6/18/07, clameter@xxxxxxx <clameter@xxxxxxx> wrote:
> Slab defragmentation occurs either
>
> 1. Unconditionally when kmem_cache_shrink is called on slab by the kernel
>    calling kmem_cache_shrink or slabinfo triggering slab shrinking. This
>    form performs defragmentation on all nodes of a NUMA system.
>
> 2. Conditionally when kmem_cache_defrag(<percentage>, <node>) is called.
>
>    The defragmentation is only performed if the fragmentation of the slab
>    is higher then the specified percentage. Fragmentation ratios are measured
>    by calculating the percentage of objects in use compared to the total
>    number of objects that the slab cache could hold.
>
>    kmem_cache_defrag takes a node parameter. This can either be -1 if
>    defragmentation should be performed on all nodes, or a node number.
>    If a node number was specified then defragmentation is only performed
>    on a specific node.

Hrm, isn't -1 usually 'this node' for NUMA systems? Maybe nr_node_ids
or MAX_NUMNODES should mean 'all nodes'?

Perhaps these would be served with some #defines?

#define NUMA_THISNODE_ID (-1)
#define NUMA_ALLNODES_ID (MAX_NUMNODES)

or something?

Thanks,
Nish
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