Re: what to revert

On 2016-05-10 13:36:32 -0400, Robert Haas wrote:
> On Tue, May 10, 2016 at 12:31 PM, Tomas Vondra
> <tomas.vondra@2ndquadrant.com> wrote:
> > The following table shows the differences between the disabled and reverted
> > cases like this:
> >
> >     sum('reverted' results with N clients)
> >    ---------------------------------------- - 1.0
> >     sum('disabled' results with N clients)
> >
> > for each scale/client count combination. So for example 4.83% means with a
> > single client on the smallest data set, the sum of the 5 runs for reverted
> > was about 1.0483x than for disabled.
> >
> >     scale        1       16       32      64      128
> >     100      4.83%    2.84%    1.21%   1.16%    3.85%
> >     3000     1.97%    0.83%    1.78%   0.09%    7.70%
> >     10000   -6.94%   -5.24%  -12.98%  -3.02%   -8.78%
> 
> /me scratches head.
> 
> That doesn't seem like noise, but I don't understand the
> scale-factor-10000 results either.

Hm. Could you change max_connections by 1 and 2 and run the 10k tests
again for each value? I wonder whether we're seing the affect of changed
shared memory alignment.

Greetings,

Andres Freund