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Comment by ahofmann | Hacker News Reader

Why do they show different compression levels in their graphs? That seems kind of fishy to me.

Looks like they choose the levels to make the compression ratios roughly equal.

> For the Silesia corpus, data compression ratios are:

    QAT-ZSTD level 9: 2.76
    zstd level 4: 2.74
    zstd level 5: 2.77

This presumably also means the best possible compression that QAT can achieve is worse than what vanilla zstd can do.

.. for small payloads.

QAT cannot compress across blocks. So as soon as your input is more than 128KB the compression ratio tanks.

Usually well below what even level 1 of software zstd does. They choose the input very carefully.

Interesting. That sounds basically perfect for ZFS where the default is 128KB blocks and zstd compression.