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x86/fpu: Optimize fpu_copy() 

Optimize fpu_copy() a bit by expanding the ->fpstate_active == 1
portion of fpu__save() into it.

( The main purpose of this change is to enable another, larger
  optimization that will be done in the next patch. )

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2015-04-27 09:59:11 +02:00
parent 48c4717f30
commit 68271c6ae7
1 changed files with 4 additions and 1 deletions
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5
arch/x86/kernel/fpu/core.c
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@ -224,7 +224,10 @@ static void fpu_copy(struct fpu *dst_fpu, struct fpu *src_fpu)
memset(&dst_fpu->state.xsave, 0, xstate_size);
copy_fpregs_to_fpstate(dst_fpu);
} else {
fpu__save(src_fpu);
preempt_disable();
if (!copy_fpregs_to_fpstate(src_fpu))
fpregs_deactivate(src_fpu);
preempt_enable();
memcpy(&dst_fpu->state, &src_fpu->state, xstate_size);
}
}