Re: Using POPCNT and other advanced bit manipulation instructions - Mailing list pgsql-hackers

From Gavin Flower
Subject Re: Using POPCNT and other advanced bit manipulation instructions
Date
Msg-id 2b3200f4-8ed8-5b62-4f9e-3319fd8f6626@archidevsys.co.nz
Whole thread Raw
In response to Using POPCNT and other advanced bit manipulation instructions  (David Rowley <david.rowley@2ndquadrant.com>)
Responses Re: Using POPCNT and other advanced bit manipulation instructions  (David Rowley <david.rowley@2ndquadrant.com>)
List 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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