Re: [Qemu-devel] [PATCH] target-sparc register window handling

[Richard Henderson]

On 10/07/2012 11:17 PM, Aurelien Jarno wrote:
> For what it worth, I measure a 4% slow down booting a sparc64 guest on a
> Core-i5 2500 machine. I guess the memcpy() of the register windows is
> more expensive that the gain on the TCG side, though it should be
> probably be confirmed using some profiling tools.

Confirmed with userland testing (running cc1plus on large input),
and I see much more than 4% slow down -- more like 15%.  I can reduce
this by adding save/restore window inc/dec optimization within the
cpu_set_cwp routine, but that only gets me back to 5% slow down.

A bit disappointing; I guess other avenues will want exploring.

Patch withdrawn.


r~