Re: Linux 4.15-rc6

[Andres Freund]

On 2017-12-31 14:57:51 -0800, Linus Torvalds wrote:
> With all the x86 pti work coming in late in the rc like this, I'm by
> now almost guaranteed to do an rc8 this release, not because there are
> any known problems, but simply because of the timing of the patches.
>
> Go forth and test,

I thought it'd be interesting to run a short benchmark to be able to
estimate the impact of the PTI work on postgres workloads (which I work
on). On my skylake laptop, a memory resident, OLTP workload with 16
connections results in:

pti=on:
tps = 220791.228297 (including connections establishing)
tps = 220836.842052 (excluding connections establishing)

pti=off:
tps = 236629.778328 (including connections establishing)
tps = 236646.598274 (excluding connections establishing)

model name      : Intel(R) Core(TM) i7-6820HQ CPU @ 2.70GHz


This isn't a complaint, I just thought it might be useful
information. If it helps for anything/anybody, I'm happy to run
additional benchmarks / provide additional information.


- Andres