Re: pglz performance

> 17 мая 2019 г., в 18:40, Gasper Zejn <zejn(at)owca(dot)info> написал(а):
>
> I've tested according to instructions at the test repo
> https://github.com/x4m/test_pglz
>
> Test_pglz is at a97f63b and postgres at 6ba500.
>
> Hardware is desktop AMD Ryzen 5 2600, 32GB RAM
>
> Decompressor score (summ of all times):
>
> NOTICE: Decompressor pglz_decompress_hacked result 6.988909
> NOTICE: Decompressor pglz_decompress_hacked8 result 7.562619
> NOTICE: Decompressor pglz_decompress_hacked16 result 8.316957
> NOTICE: Decompressor pglz_decompress_vanilla result 10.725826

Thanks, Gasper! Basically we observe same 0.65 time reduction here.

That's very good that we have independent scores.

I'm still somewhat not sure that score is fair, on payload 000000010000000000000008 we have vanilla decompression sometimes slower than hacked by few percents. And this is especially visible on AMD. Degradation for 000000010000000000000008 sliced by 8Kb reaches 10%

I think this is because 000000010000000000000008 have highest entropy.It is almost random and matches are very short, but present.
000000010000000000000008
Entropy = 4.360546 bits per byte.
000000010000000000000006
Entropy = 1.450059 bits per byte.
000000010000000000000001
Entropy = 2.944235 bits per byte.
shakespeare.txt
Entropy = 3.603659 bits per byte
16398
Entropy = 1.897640 bits per byte.

Best regards, Andrey Borodin.