Re: [RFC 00/15] x86_64: Optimize percpu accesses

From: H. Peter Anvin
Date: Thu Jul 10 2008 - 15:39:53 EST


Mike Travis wrote:

The biggest growth came from moving all the xxx[NR_CPUS] arrays into
the per cpu area. So you free up a huge amount of unused memory when
the NR_CPUS count starts getting into the ozone layer. 4k now, 16k
real soon now, ??? future?


Even (or perhaps especially) so, allocating the percpu area in 2 MB increments is a total nonstarter. It hurts the small, common configurations way too much. For SGI, it's probably fine.

-hpa
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