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From: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>
To: John Baldwin <jhb@freebsd.org>
Subject: Re: Multiple page size support on FreeBSD?
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 (wojtek.tensor.gdynia.pl [127.0.0.1]); Wed, 10 Apr 2013 19:49:10 +0200 (CEST)
Cc: freebsd-hackers@freebsd.org, Benjamin Kaduk <kaduk@mit.edu>,
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> How do your tests work?  Do you examine PTEs directly to check for superpages
> or are you relying on the vm.pmap.pde sysctls?

the later.

anyway - algorithm described on list - that heuristics detects consecutive 
page access doesn't really help the urgent case - RANDOM access to large 
amount of memory.

sequential access will get minimal improvement.

IMHO the only way that really make sens is to add options to madvise to 
give kernel information about usage.