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    SubjectRe: [Intel-IOMMU 02/10] Library routine for pre-allocat pool handling
    On Mon, 11 Jun 2007 13:44:42 -0700
    "Keshavamurthy, Anil S" <> wrote:

    > In the first implementation of ours, we had used mempools api's to
    > allocate memory and we were told that mempools with GFP_ATOMIC is
    > useless and hence in the second implementation we came up with
    > resource pools ( which is preallocate pools) and again as I understand
    > the argument is why create another when we have slab allocation which
    > is similar to this resource pools.

    Odd. mempool with GFP_ATOMIC is basically equivalent to your
    resource-pools, isn't it?: we'll try the slab allocator and if that failed,
    fall back to the reserves.

    It's missing the recharge-from-a-kernel-thread functionality but that can be
    added easily enough if it's useful. It's slightly abusive of the mempool
    philosophy, but it's probably better to do that than to create a new and
    very-similar thing.

    > Hence, can I assume that the conclusion of this
    > discussion is to use kmem_cache_alloc() functions
    > to allocate memory in dma_map_{single|sg} API's?
    > Again, if dma_map_{single|sg} API's fails due to
    > failure to allocate memory, the only thing that can
    > be done is to panic as this is what few of the other
    > IOMMU implementation is doing today.

    If the only option is to panic then something's busted. If it's network IO
    then there should be a way of dropping the frame. If it's disk IO then we
    should report the failure and cause an IO error.

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      Last update: 2007-06-11 23:17    [W:0.052 / U:4.460 seconds]
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