Messages in this thread | | | Date | Fri, 12 Nov 1999 19:58:10 +0100 (CET) | From | Ingo Molnar <> | Subject | Re: 2.3.27 always keeping 15M free? |
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On Fri, 12 Nov 1999, Alan Cox wrote:
> > I've got a P90 laptop with 40M *1. Somewhere between 2.3.24 and > > 2.3.27-final the kernel started keeping 15M or more free all the time. > > On a 40M laptop that makes a big difference. *smile* > > 2.3.27 seperates DMA memory from the rest but forgets that you need to > pull from the DMA pool for a failing GFP_KERNEL allocation.
well, we automatically fall back to lower level zones, check out __get_pages():
do { page = rmqueue(zone, order); if (page) return page; } while (zone-- != zones) ;
So we are falling back from ZONE_HIGHMEM to ZONE_NORMAL to ZONE_DMA.
> You also need to figure very fast when you will need to do this otherwise > your performance goes through the floor.
it should be rather fast. But if higher-order zones are completely allocated then we are under heavy memory pressure anyway. But it should work already.
-- mingo
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