Re: Re: [COMMITTERS] pgsql: Avoid extra locks in GetSnapshotData if old_snapshot_threshold <

Hi Kevin,

On 2016-04-13 12:21:10 -0700, Andres Freund wrote:
> 0:
> progress: 100.0 s, 593351.0 tps, lat 0.215 ms stddev 0.118
> progress: 200.0 s, 594035.9 tps, lat 0.215 ms stddev 0.118
> progress: 300.0 s, 594013.3 tps, lat 0.215 ms stddev 0.117
>
> -1:
> progress: 100.0 s, 600835.3 tps, lat 0.212 ms stddev 0.049
> progress: 200.0 s, 601466.1 tps, lat 0.212 ms stddev 0.048
> progress: 300.0 s, 601529.5 tps, lat 0.212 ms stddev 0.047
>
> reverted:
> progress: 100.0 s, 612676.6 tps, lat 0.208 ms stddev 0.048
> progress: 200.0 s, 613214.3 tps, lat 0.208 ms stddev 0.047
> progress: 300.0 s, 613384.3 tps, lat 0.208 ms stddev 0.047

Setting it to 1 gives:
progress: 100.0 s, 115413.7 tps, lat 1.107 ms stddev 1.240
progress: 200.0 s, 114907.4 tps, lat 1.113 ms stddev 1.244
progress: 300.0 s, 115621.4 tps, lat 1.106 ms stddev 1.238

If you want me to rn some other tests I can, but ISTM we have the data
we need?

- Andres