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    SubjectRe: Problem: Out of memory after 2days with 2GB RAM

    > > Try the patch below. It should improve code generation too.
    > >
    > > I discussed this with Tomas previously and he says the hw is capable of
    > > doing 20 fragments per frame (wonder why, Broadcom can do an unlimited
    > > number...) but he complained about the networking stack not being able
    > > to.
    > This is scatter gather buffers that can be kicked in one DMA transaction.
    > Well, the hardware needs to support IP checksumming for that, hence,
    > > afaik, only two fragments can ever be used (one for hw header, one for
    > > frame)
    > This I still don't understand why but everybody is already tired to
    > explaining me why.. :) Just need to find time to dig into it.

    And you can safely decrease the allocation to 10% as I do in my patch
    because once you understand you'll see that you cannot possibly use
    more. Hence, you can ack this patch ;)

    > > This cuts the allocation to 10%, or (under) a page in all cases.
    > Probably. it would be safe to use vmalloc for allocating txb anyway.
    > I'll give it a try.

    Yeah, but why bother if we can just allocate 10% of the size, waste a
    lot less memory etc. mac80211 isn't going to pass in a scatter/gather
    frame anyway.

    > There was already discussion on LKML about memory allocation problems
    > on X86_64, which might explain this regression. This didn't happen
    > before.

    Doesn't really matter, iwlwifi is _wasting_ this allocation, it cannot
    possibly use all those buffers anyway.

    The more interesting thing is the pci_alloc_consistent allocation right
    below that is also _huge_, but that's because of the stupid hardware
    design, or can the hardware cope with having the descriptors non-linear
    in memory?

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