| From: | Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz> |
|---|---|
| To: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Cc: | Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com> |
| Subject: | Re: Using POPCNT and other advanced bit manipulation instructions |
| Date: | 2018-12-20 07:17:28 |
| Message-ID: | 2b3200f4-8ed8-5b62-4f9e-3319fd8f6626@archidevsys.co.nz |
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| Lists: | pgsql-hackers |
On 20/12/2018 18:53, David Rowley wrote
[...]
> Patched:
>
> postgres=# analyze t1;
> Time: 680.833 ms
> Time: 699.976 ms
> Time: 695.608 ms
> Time: 676.007 ms
> Time: 693.487 ms
> Time: 726.982 ms
> Time: 677.835 ms
> Time: 688.426 ms
>
> Master:
>
> postgres=# analyze t1;
> Time: 721.837 ms
> Time: 756.035 ms
> Time: 734.545 ms
> Time: 751.969 ms
> Time: 730.140 ms
> Time: 724.266 ms
> Time: 713.625 ms
>
> (+3.66% avg)
[...]
Looking at the normalized standard deviations, the patched results have
a higher than 5% chance of being better simply by chance. I suspect
that you have made an improvement, but the statistics are not convincing.
I can supply detailed working if you want.
Cheers,
Gavin
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