Re: [patch 13/26] Xen-paravirt_ops: Consistently wrap paravirt opscallsites to make them patchable

From: Zachary Amsden
Date: Tue Mar 20 2007 - 15:54:43 EST


Andi Kleen wrote:
One thing I was pondering was to replace the expensive popfs with

bt $IF,(%rsp) jnc 1f sti
1:

But would be mostly a P4 optimization again and I'm not 100% sure it is
worth it.

Worth it on 32-bit. On AMD64, probably not. On Intel 64-bit, maybe, but less important than in P4 days.

This could change character completely if used at the tail of a function where you now have

sti; 1: ret

Which generates an interrupt holdoff on the ret, an unusual thing to do.

Zach
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/