Messages in this thread | | | Date | Thu, 13 Jan 2000 18:06:07 +0100 (CET) | From | Andrea Arcangeli <> | Subject | Re: [RFC] 2.3.39 zone balancing |
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On Thu, 13 Jan 2000, Rik van Riel wrote:
>On Wed, 12 Jan 2000, Kanoj Sarcar wrote: > >> --- mm/page_alloc.c Tue Jan 11 11:00:31 2000 >> +++ mm/page_alloc.c Tue Jan 11 23:59:35 2000 >> + cumulative += size; >> + mask = (cumulative >> 7); >> + if (mask < 1) mask = 1; >> + zone->pages_low = mask*2; >> + zone->pages_high = mask*3; >> zone->low_on_memory = 0; > >I think that busier machines probably have a larger need >for DMA memory than this code fragment will give us. I >have the gut feeling that we'll want to keep about 512kB >or more free in the lower 16MB of busy machines... > >(if only because such a large amount of free pages in >such a small part of the address space will give us >higher-order free pages)
That's only a workaround because the page-freeing mechanism is currently not aware about fragmentation and about the order of the request we asked for.
So such code shouldn't be wrote assuming the page-freeing is weak as now.
Supposing it's smart we don't need to take lots of memory free in the dma zone to allow high order allocations to succeed.
Andrea
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