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x86, fpu: split FPU state from task struct - v5

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Split the FPU save area from the task struct. This allows easy migration
of FPU context, and it's generally cleaner. It also allows the following
two optimizations:

1) only allocate when the application actually uses FPU, so in the first
lazy FPU trap. This could save memory for non-fpu using apps. Next patch
does this lazy allocation.

2) allocate the right size for the actual cpu rather than 512 bytes always.
Patches enabling xsave/xrstor support (coming shortly) will take advantage
of this.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Suresh Siddha
2008-03-10 15:28:04 -07:00
committed by Ingo Molnar
parent fa5c463941
commit 61c4628b53
16 changed files with 161 additions and 90 deletions
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2
arch/x86/kernel/process_32.c
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@ -703,7 +703,7 @@ struct task_struct * __switch_to(struct task_struct *prev_p, struct task_struct
/* we're going to use this soon, after a few expensive things */
if (next_p->fpu_counter > 5)
prefetch(&next->i387.fxsave);
prefetch(next->xstate);
/*
* Reload esp0.