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

From: H. Peter Anvin
Date: Thu Jul 10 2008 - 13:58:24 EST


Eric W. Biederman wrote:
Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx> writes:

H. Peter Anvin wrote:

but there is a distinct lack of wiggle room, which can be resolved
either by using negative offsets, or by moving the kernel text area up a
bit from -2 GB.
Lets say we reserve 256MB of cpu alloc space per processor.

First off right now reserving more than about 64KB is ridiculous. We rightly
don't have that many per cpu variables.

Almost half a megabyte in current allyesconfig, and that is not including dynamic allocations at all.

-hpa
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