iq2_xxs: tune quantization #5320
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We get slightly better PPL, and we cut quantization time in nearly half. The trick is to 1st quantize without forcing points onto the E8-lattice. We can then use a narrower search range around the block scale that we got that way.
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Could this applied to other IQ quants？ |
ggerganov
approved these changes
Feb 5, 2024
Yes, but with much less gain. I.e., one gets an increase in PPL if one reduces the scale search range as aggressively as here, or one can keep about the same PPL but with much lower speedup. |
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Any noticeable speed-up you can offer us with a close to equal perplexity is interresting for the CPU poor, @ikawrakow! |
jordankanter
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to jordankanter/llama.cpp
that referenced
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Mar 13, 2024
We get slightly better PPL, and we cut quantization time in nearly half. The trick is to 1st quantize without forcing points onto the E8-lattice. We can then use a narrower search range around the block scale that we got that way. Co-authored-by: Iwan Kawrakow <[email protected]>
hodlen
pushed a commit
to hodlen/llama.cpp
that referenced
this pull request
Apr 1, 2024
We get slightly better PPL, and we cut quantization time in nearly half. The trick is to 1st quantize without forcing points onto the E8-lattice. We can then use a narrower search range around the block scale that we got that way. Co-authored-by: Iwan Kawrakow <[email protected]>
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We get slightly better PPL, and we cut quantization time in nearly half.
The trick is to 1st quantize without forcing points onto the E8-lattice. We can then use a narrower search range around the block scale that we got that way, which gives the significant reduction in quantization time.
The code becomes simpler too, so it is a win-win.
Here is a comparison between PPL with this PR and PR #4773 for a context of 4096