Messages in this thread | | | Date | Tue, 20 Mar 2007 11:54:25 -0800 | From | Zachary Amsden <> | Subject | Re: [patch 13/26] Xen-paravirt_ops: Consistently wrap paravirt ops callsites to make them patchable |
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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.
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