GGUF quantizations overview

README.md

Which GGUF is right for me? (Opinionated)

Good question! I am collecting human data on how quantization affects outputs. See here for more information: ggerganov/llama.cpp#5962

In the meantime, use the largest that fully fits in your GPU. If you can comfortably fit Q4_K_S, try using a model with more parameters.

llama.cpp feature matrix

See the wiki upstream: https://github.com/ggerganov/llama.cpp/wiki/Feature-matrix

KL-divergence statistics for Mistral-7B

• Last updated 2024-02-27 (add IQ4_XS).
• imatrix from wiki.train, 200*512 tokens.
• KL-divergence measured on wiki.test.

	Bits per weight	KL-divergence median	KL-divergence q99	Top tokens differ	ln(PPL(Q)/PPL(base))
IQ1_S	1.78	0.5495	5.5174	0.3840	0.9235
IQ2_XXS	2.20	0.1751	2.4983	0.2313	0.2988
IQ2_XS	2.43	0.1146	1.7693	0.1943	0.2046
IQ2_S	2.55	0.0949	1.6284	0.1806	0.1722
IQ2_M	2.76	0.0702	1.0935	0.1557	0.1223
Q2_K_S	2.79	0.0829	1.5111	0.1735	0.1600
Q2_K	3.00	0.0588	1.0337	0.1492	0.1103
IQ3_XXS	3.21	0.0330	0.5492	0.1137	0.0589
IQ3_XS	3.32	0.0296	0.4550	0.1071	0.0458
Q3_K_S	3.50	0.0304	0.4481	0.1068	0.0511
IQ3_S	3.52	0.0205	0.3018	0.0895	0.0306
IQ3_M	3.63	0.0186	0.2740	0.0859	0.0268
Q3_K_M	3.89	0.0171	0.2546	0.0839	0.0258
Q3_K_L	4.22	0.0152	0.2202	0.0797	0.0205
IQ4_XS	4.32	0.0088	0.1082	0.0606	0.0079
IQ4_NL	4.56	0.0085	0.1077	0.0605	0.0074
Q4_K_S	4.57	0.0083	0.1012	0.0600	0.0081
Q4_K_M	4.83	0.0075	0.0885	0.0576	0.0060
Q5_K_S	5.52	0.0045	0.0393	0.0454	0.0005
Q5_K_M	5.67	0.0043	0.0368	0.0444	0.0005
Q6_K	6.57	0.0032	0.0222	0.0394	−0.0008

ROCm benchmarks for Mistral-7B

• Last updated 2024-03-15 (bench #6083).

	GiB	pp512 -ngl 99	tg128 -ngl 99	pp512 -ngl 0	tg128 -ngl 0	pp512 -ngl 0 #6083
IQ1_S	1.50	709.29	74.85	324.35	15.66	585.61
IQ2_XS	2.05	704.52	58.44	316.10	15.11	557.68
IQ3_XS	2.79	682.72	45.79	300.61	10.49	527.83
IQ4_XS	3.64	712.96	64.17	292.36	11.06	495.92
Q4_0	3.83	870.44	63.42	310.94	10.44	554.56
Q5_K	4.78	691.40	46.52	273.83	8.54	453.58
Q6_K	5.53	661.98	47.57	261.16	7.34	415.22
Q8_0	7.17	881.95	39.74	270.70	5.74	440.44
f16	13.49			211.12	3.06	303.60

@complexinteractive Good question. Probably similar, but I don't have the hardware to generate KL-divergence on a 70b model.

Any chance on seeing you generate KL-divergence stats for models in range (30B to Mixtral)?

Running unquantized mixtral would take over 180 GB of memory, which I don't have (GGUF can't store tensors in BF16).

Something like Command-R might work, after ggerganov/llama.cpp#6104 is fixed.

Awesome,
could you please, also graph inference speed on CPU and GPU across different quantizations, I observe that IQ3_S much slower than Q5_K_M on x86 CPU

@Artefact2 Thanks for your document.

I am beginner in Quantization, I have a hard time to figuring out what does the "I", "K", "M" mean in LLM model names.
e.g. IQ3_M, IQ3_XXS, Q3_K_M

I can guess Q means: Quantization, but what about M, XS, XXS are they an indicator for size?(what size??)
How about "I" and "K"?

Appreciate if you could explain them in a very plain language.

@\Artefact2 Thanks for your document.

I am beginner in Quantization, I have a hard time to figuring out what does the "I", "K", "M" mean in LLM model names. e.g. IQ3_M, IQ3_XXS, Q3_K_M

I can guess Q means: Quantization, but what about M, XS, XXS are they an indicator for size?(what size??) How about "I" and "K"?

Appreciate if you could explain them in a very plain language.

@franva
I started typing an explainer and then it got a little long so i turned it into a Rentry.

@cha0sbuster Hi man, I have read your writing, you did a great job~! I think you can event make your Rentry note into a article on Medium , I'm sure people like me who knows a bit AI but when looking at the naming of LLM and gets confused and frustrated will appreciate your great explanation :)

One more question, I noticed that when you use "I", you use it together with "Q", but when you use "K", you mentioned it alone. Why?

@cha0sbuster Hi man, I have read your writing, you did a great job~! I think you can event make your Rentry note into a article on Medium , I'm sure people like me who knows a bit AI but when looking at the naming of LLM and gets confused and frustrated will appreciate your great explanation :)

thanks! ^^ I used Rentry because it's standard in the parts of the community I frequent, and my presence on Medium is ill-fit for this (I write about music there already.)

One more question, I noticed that when you use "I", you use it together with "Q", but when you use "K", you mentioned it alone. Why?

Since they're split by underscore it's more common to say "IQ" or "K". It's just convention.

okiee, thank you !!! All done.