Re: [Qemu-devel] [RFC 7/8] util/qht: atomically set b->hashes

[Paolo Bonzini]

On 19/09/2016 21:06, Emilio G. Cota wrote:
> Let me then just point out that this comes at a small perf loss.
> 
> Running 'taskset -c 0 tests/qht-bench -n 1 -d 10' (i.e. all lookups) 10 times,
> we get:
> 
> before the patch:
>  $ ./mean.pl 34.04 34.24 34.38 34.25 34.18 34.51 34.46 34.44 34.29 34.08
>  34.287 +- 0.160072900059109
> after:
>  $ ./mean.pl 33.94 34.00 33.52 33.46 33.55 33.71 34.27 34.06 34.28 34.58
>  33.937 +- 0.374731014640279
> 
> But hey we can live with that.

Hmm it shouldn't.  I'll take a look at the generated assembly...

Paolo