Re: [BK-2.5] Move "used FPU status" into new non-atomic

[David S. Miller]

   From: Linus Torvalds <[e-mail]>
   Date: Mon, 10 Mar 2003 11:25:55 -0800 (PST)
   
   > Are you preserving FPU state across fork() on x86?  If so, what do you
   > think might rely on this?
   
   Probably nothing per se. HOWEVER, we'd still need to save the state for 
   rounding etc, so we might as well save it all.
   
I see.

We preserve the rounding/etc. modes on sparc, we merely zap the actual
FPU registers around the system call.

And that's like 4 L2 cache lines of registers on sparc64, so there
really is a benefit from only saving the mode register across a system
call.