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x86-64: move unlazy_fpu() into lazy cpu state part of context switch 

Make sure that unlazy_fpu()'s stts gets batched along with the other
cpu state changes during context switch.  (32-bit already does this.)

This makes sure it gets batched when running paravirtualized.

[ Impact: optimise paravirtual FPU context switch ]

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Jeremy Fitzhardinge 2009-04-24 00:50:27 -07:00
parent 2fcddce10f
commit 16d9dbf0c2
1 changed files with 3 additions and 3 deletions
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6
arch/x86/kernel/process_64.c
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@ -419,6 +419,9 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
load_TLS(next, cpu);
/* Must be after DS reload */
unlazy_fpu(prev_p);
/*
* Leave lazy mode, flushing any hypercalls made here.
* This must be done before restoring TLS segments so
@ -459,9 +462,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
prev->gsindex = gsindex;
/* Must be after DS reload */
unlazy_fpu(prev_p);
/*
* Switch the PDA and FPU contexts.
*/