tree 04413a1f18c6f49688d6008b583b20a287920a0f
parent 2f766d16062d0147edff91be15de4a950667ca42
author Stephane Eranian <eranian@hpl.hp.com> 1159260748 +0200
committer Andi Kleen <andi@basil.nowhere.org> 1159260748 +0200

[PATCH] x86-64 TIF flags for debug regs and io bitmap in ctxsw

Hello,

Following my discussion with Andi. Here is a patch that introduces
two new TIF flags to simplify the context switch code in __switch_to().
The idea is to minimize the number of cache lines accessed in the common
case, i.e., when neither the debug registers nor the I/O bitmap are used.

This patch covers the x86-64 modifications. A patch for i386 follows.

Changelog:
	- add TIF_DEBUG to track when debug registers are active
	- add TIF_IO_BITMAP to track when I/O bitmap is used
	- modify __switch_to() to use the new TIF flags

<signed-off-by>: eranian@hpl.hp.com

Signed-off-by: Andi Kleen <ak@suse.de>