Messages in this thread | | | Date | Thu, 02 Jun 2005 09:56:18 +1000 | From | Nick Piggin <> | Subject | Re: Avoiding external fragmentation with a placement policy Version 12 |
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Mike Kravetz wrote: > On Thu, Jun 02, 2005 at 09:09:23AM +1000, Nick Piggin wrote: > >>It adds a lot of complexity to the page allocator and while >>it might be very good, the only improvement we've been shown >>yet is allocating lots of MAX_ORDER allocations I think? (ie. >>not very useful) >> > > > Allocating lots of MAX_ORDER blocks can be very useful for things > like hot-pluggable memory. I know that this may not be of interest > to most. However, I've been combining Mel's defragmenting patch > with the memory hotplug patch set. As a result, I've been able to > go from 5GB down to 544MB of memory on my ppc64 system via offline > operations. Note that ppc64 only employs a single (DMA) zone. So, > page 'grouping' based on use is coming mainly from Mel's patch. >
Back in the day, Linus would tell you to take a hike if you wanted to complicate the buddy allocator to better support memory hotplug ;)
I don't know what's happened to him now though, he seems to have gone a little soft on you enterprise types.
Seriously - thanks for the data point, I had an idea that you guys wanted this for mem hotplug.
-- SUSE Labs, Novell Inc.
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