Messages in this thread | | | Date | Fri, 22 Oct 1999 08:47:05 -0400 (EDT) | From | <> | Subject | Re: mm and DMA devices |
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On Thu, 21 Oct 1999, Dan Hollis wrote:
> On Thu, 21 Oct 1999 kernel@kvack.org wrote: > > memory lists (say 1 per bit of significance above 24 bits). Practically, > > I have to ask what the value in this is. Do you really need to allocate > > > 16 MB in the normal use of a bloody sound card? > > No, but you have to make sure memory below 16mb is available :} > > Or even for many PCI cards, below 1gb or 2gb. > > Itd be *very* embarassing to have 4gb of ram, 2gb used, and not be able to > use your PCI soundcard because it cant allocate ram below 1gb.
Do the math. Right now, GFP_DMA memory is the last part of system memory to be allocated from. Unless GFP_ATOMIC allocations consume all of the freepages.min memory reserve (which, for starters, is unlikely -- plus GFP_ATOMIC allocations are typically short term allocations for network buffers), you will be able to get GFP_DMA memory. That's the entire point of the changes made to the allocator. They may have been subtle, but their impact should be enourmously positive.
-ben
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