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flate: remove compressor.hash field #589

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Jacalz opened this issue May 11, 2022 · 9 comments · Fixed by #590
Closed

flate: remove compressor.hash field #589

Jacalz opened this issue May 11, 2022 · 9 comments · Fixed by #590

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@Jacalz
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Jacalz commented May 11, 2022

I found the commit golang/go@949b3e9 recently landing for Go 1.19. From what I can tell from the code here in this project, most of the code that is removed in that commit is already present here. Would it be possible to apply something similar in this project?
@Jacalz
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Jacalz commented May 11, 2022

I haven’t quite been able to find the CL mentioned in the commit message (I’m writing this on my phone) but I suspect https://github.com/golang/go/commits/master/src/compress/flate would help.

@klauspost
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@Jacalz I doubt it will make much of a difference, but it is also cannot hurt.

klauspost added a commit that referenced this issue May 11, 2022
@klauspost
flate: Faster hashing for level 7-9
ea97c77 
Remove stateful hash and need for AND operation.

(benchmark pending)

Fixes #589
@klauspost klauspost mentioned this issue May 11, 2022
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@klauspost
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klauspost commented May 11, 2022 •
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It doesn't. Even with removing a now un-needed AND instruction. If anything it seems to make it a tiny bit slower, though that could just be noise.

@Jacalz
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Jacalz commented May 19, 2022 •
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It looks like golang/go@c25c371 landed after the commit mentioned above. I don't know if it is applicable here and if it makes a difference.

@klauspost
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@Jacalz That is totally BS. The ONLY relevant difference in the ENCODER is

Encode/Digits/Speed/1e5-4          1.65ms ± 2%     1.70ms ± 4%   +2.77%  (p=0.003 n=8+10)
Encode/Newton/Default/1e6-4        58.0ms ± 2%     57.0ms ± 1%   -1.59%  (p=0.001 n=9+9)

The rest is DECODER differences, completely unaffected by this change.

@Jacalz
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Jacalz commented May 23, 2022 •
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Yeah, I suspected as much. All those upstream commits as of late seem to make almost no changes and report massive speedups. Something is wonky. Sorry for the unnecessary noice.

@klauspost
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Yeah, not bothering with this one. Maybe next time I'm around that code, if it is there.

@Jacalz
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Jacalz commented May 23, 2022

Have you reached any conclusion on the open PR?

@klauspost
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@Jacalz Ah, yeah... Thought I had merged it. Putting it in. It will probably sometimes be faster (since it has more time to finish the calculation) and sometimes not (pipeline stalls while calculating).

klauspost added a commit that referenced this issue May 23, 2022
@klauspost
flate: Faster hashing for level 7-9 (#590)
4703195 
Remove stateful hash and need for AND operation.

Benchmarks show no change.

Fixes #589
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flate: Inplace hashing for level 7-9 klauspost/compress
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@klauspost @Jacalz