Messages in this thread Patch in this message |  | | From | riel@redhat ... | Subject | [PATCH 8/8] x86,fpu: also check fpu_lazy_restore when use_eager_fpu | Date | Fri, 6 Feb 2015 15:02:05 -0500 |
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From: Rik van Riel <riel@redhat.com>
With Oleg's patch "x86, fpu: don't abuse FPU in kernel threads if use_eager_fpu()", kernel threads no longer have an FPU state even on systems with use_eager_fpu()
That in turn means that a task may still have its FPU state loaded in the FPU registers, if the task only got interrupted by kernel threads from when it went to sleep, to when it woke up again.
In that case, there is no need to restore the FPU state for this task, since it is still in the registers.
The kernel can simply use the same logic to determine this as is used for !use_eager_fpu() systems.
Signed-off-by: Rik van Riel <riel@redhat.com> --- arch/x86/include/asm/fpu-internal.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h index 06af286593d7..723b74da0685 100644 --- a/arch/x86/include/asm/fpu-internal.h +++ b/arch/x86/include/asm/fpu-internal.h @@ -457,7 +457,7 @@ static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct ta task_disable_lazy_fpu_restore(old); if (fpu.preload) { new->thread.fpu_counter++; - if (!use_eager_fpu() && fpu_lazy_restore(new, cpu)) + if (fpu_lazy_restore(new, cpu)) fpu.preload = 0; else prefetch(new->thread.fpu.state); -- 1.9.3
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