Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [rfc patch] i386: don't save eflags on task switch | Date | Sat, 4 Nov 2006 02:36:20 +0100 |
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On Saturday 04 November 2006 01:46, Linus Torvalds wrote: > > On Fri, 3 Nov 2006, Chuck Ebbert wrote: > > > > There is no real need to save eflags in switch_to(). Instead, > > we can keep a constant value in the and always > > restore that. > > I don't really see the point. The "pushfl" isn't the expensive part, and > it gives sane and expected semantics. > > The "popfl" is the expensive part, and that's the thing that can't really > even be removed.
Well it could -- i made an attempt at it recently. But it would add a little code to the SYSENTER entry code (basically a test / conditional jump after the pushfl there) to clear any rogue flags on entry. Not sure it is worth it. That is why i didn't put this patch in.
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