Re: [GSOC 17] Eliminate O(N^2) scaling from rw-conflict tracking in serializable transactions

On Sat, Mar 11, 2017 at 8:39 PM, Mengxing Liu
<liu-mx15(at)mails(dot)tsinghua(dot)edu(dot)cn> wrote:

>> The worst problems have been
>> seen with 32 or more cores on 4 or more sockets with a large number
>> of active connections. I don't know whether you have access to a
>> machine capable of putting this kind of stress on it (perhaps at
>> your university?), but if not, the community has access to various
>> resources we should be able to schedule time on.
>
> There is a NUMA machine ( 120 cores, 8 sockets) in my lab.

Fantastic! Can you say a bit more about the architecture and OS?

> I think it's enough to put this kind of stress.

The researchers who saw this bottleneck reported that performance
started to dip at 16 cores and the problem was very noticeable at 32
cores. A stress test with 120 cores on 8 sockets will be great!

I think perhaps the first milestone on the project should be to
develop a set of benchmarks we want to compare to at the end. That
would need to include a stress test that clearly shows the problem
we're trying to solve, along with some cases involving 1 or two
connections -- just to make sure we don't harm performance for
low-contention situations.

--
Kevin Grittner