Re: [Qemu-devel] performance of qemu

[Fabrice Bellard <fabrice.bellard@free.fr>]

Johan Rydberg wrote:
> Hi,
> 
> has anyone of you guys (Fabrice et al) done any performance measurements of
> QEMU?  I'm particular intrested in the performance of functions that
> set the condition codes.  

I plan to publish soon some benchmarks against bochs and native execution.

> If I'm not mistaken, the condition codes is simulated using two values and
> an operator specifying what type of insn that generated the condition codes.

OK.

> When is the full eflags register generated?  In the epilogue of a translated
> block, or when ever an insn/callback reads the eflag register?

Only when an instruction really needs the full eflags register (such as 
pushf).

> Is any optmization done in the case that two insns that kill the condition 
> codes? (example: two insns that kills the condition codes, but no insn between 
> them that uses it).

Yes.

Fabrice.