Messages in this thread | | | Date | Thu, 3 Nov 2005 11:08:01 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19 |
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On Thu, 3 Nov 2005, Martin J. Bligh wrote: > > Ha. Just because I don't think I made you puke hard enough already with > foul approximations ... for order 2, I think it's
Your basic fault is in believing that the free watermark would stay constant.
That's insane.
Would you keep 8MB free on a 64MB system?
Would you keep 8MB free on a 8GB system?
The point being, that if you start with insane assumptions, you'll get insane answers.
The _correct_ assumption is that you aim to keep some fixed percentage of memory free. With that assumption and your math, finding higher-order pages is equally hard regardless of amount of memory.
Now, your math then doesn't allow for the fact that buddy automatically coalesces for you, so in fact things get _easier_ with more memory, but hey, that needs more math than I can come up with (I never did it as math, only as simulations with allocation patterns - "smart people use math, plodding people just try to simulate an estimate" ;)
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