Messages in this thread | | | Date | Thu, 26 Jan 2006 15:24:30 -0800 | From | Matthew Dobson <> | Subject | Re: [patch 3/9] mempool - Make mempools NUMA aware |
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Christoph Lameter wrote: > On Thu, 26 Jan 2006, Matthew Dobson wrote: > > >>Not all requests for memory from a specific node are performance >>enhancements, some are for correctness. With large machines, especially as > > > alloc_pages_node and friends do not guarantee allocation on that specific > node. That argument for "correctness" is bogus.
alloc_pages_node() does not guarantee allocation on a specific node, but calling __alloc_pages() with a specific nodelist would.
>>>You do not need this.... >> >>I do not agree... > > > There is no way that you would need this patch.
My goal was to not change the behavior of the slab allocator when inserting a mempool-backed allocator "under" it. Without support for at least *requesting* allocations from a specific node when allocating from a mempool, this would change how the slab allocator works. That would be bad. The slab allocator now does not guarantee that, for example, a kmalloc_node() request is satisfied by memory from the requested node, but it does at least TRY. Without adding mempool_alloc_node() then I would never be able to even TRY to satisfy a mempool-backed kmalloc_node() request from the correct node. I believe that would constitute an unacceptable breakage from normal, documented behavior. So, I *do* need this patch.
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