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@pwilkin pwilkin commented Sep 18, 2025

EDIT: README FIRST
This is an implementation of a new type of attention gating in GGML.
Therefore, this implementation will be focused on CORRECTNESS ONLY.
Speed tuning and support for more architectures will come in future PRs.
Please do not spam this threads with reports about performance, especially on backend architectures (CUDA, Vulkan).

CURRENT STATE: rebase complete, waiting for review / decision on chunking something's broken so need to debug

===
It's been a real learning experience, not gonna lie, but if someone with hybrid model implementation experience (@gabe-l-hart ?) has some quick tips, I'd be grateful.

Currently at the stage of "graph builds, but first decode complains about wrong memory model", probably not building the inputs correctly.

Resolves #15940

@github-actions github-actions bot added python python script changes ggml changes relating to the ggml tensor library for machine learning labels Sep 18, 2025
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I'll try to get into it in more detail soon, but here are a few general thoughts after quickly skimming the PR:

  1. The structure of what you've got smells correct, so it's likely close, but missing something small yet critical
  2. A full repro with the error it's raising would definitely help debug
  3. My debugging process for this would be:
    1. Make sure tokenization is solid (print statements as necessary to compare tokens before input)
    2. Use llama-eval-callback to dump tensors for a single prefill step
    3. Run an identical single prefill with the reference impl (transformers or otherwise), and inject prints as needed to dump tensors along the way
    4. Visually comb through them (particularly the sum at each point) to see where things start diverging significantly

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It's been a real learning experience, not gonna lie, but if someone with hybrid model implementation experience (@gabe-l-hart ?) has some quick tips, I'd be grateful.

Currently at the stage of "graph builds, but first decode complains about wrong memory model", probably not building the inputs correctly.

Resolves #15940

interesting, maybe we can learn together

@pwilkin pwilkin marked this pull request as draft September 19, 2025 08:07
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pwilkin commented Sep 19, 2025

  1. A full repro with the error it's raising would definitely help debug

Running llama-cli -m reference/qwen3_next_500m/Qwen3_Next_500M-8x417M-BF16.gguf -ngl 999 -p "Who are " yields this weird memory error:

#0  __syscall_cancel_arch () at ../sysdeps/unix/sysv/linux/x86_64/syscall_cancel.S:56
56      in ../sysdeps/unix/sysv/linux/x86_64/syscall_cancel.S
#1  0x000070552b29eb63 in __internal_syscall_cancel (a1=<optimized out>, a2=<optimized out>, a3=<optimized out>, a4=<optimized out>, a5=0, a6=0, nr=61) at ./nptl/cancellation.c:49
warning: 49     ./nptl/cancellation.c: No such file or directory
#2  __syscall_cancel (a1=<optimized out>, a2=<optimized out>, a3=<optimized out>, a4=<optimized out>, a5=a5@entry=0, a6=a6@entry=0, nr=61) at ./nptl/cancellation.c:75
75      in ./nptl/cancellation.c
#3  0x000070552b31afdf in __GI___wait4 (pid=<optimized out>, stat_loc=<optimized out>, options=<optimized out>, usage=<optimized out>) at ../sysdeps/unix/sysv/linux/wait4.c:30
warning: 30     ../sysdeps/unix/sysv/linux/wait4.c: No such file or directory
#4  0x000070552bb45c31 in ggml_print_backtrace () at /devel/tools/llama.cpp/ggml/src/ggml.c:196
warning: Source file is more recent than executable.
196             waitpid(child_pid, NULL, 0);
#5  0x000070552bb45de5 in ggml_abort (file=0x70552bbcdac8 "/devel/tools/llama.cpp/ggml/src/ggml-backend.cpp", line=189, fmt=0x70552bbcd8af "GGML_ASSERT(%s) failed") at /devel/tools/llama.cpp/ggml/src/ggml.c:230
230             ggml_print_backtrace();
#6  0x000070552bb6091e in ggml_backend_buffer_get_type (buffer=0x0) at /devel/tools/llama.cpp/ggml/src/ggml-backend.cpp:189
189         GGML_ASSERT(buffer);
#7  0x000070552bb6080e in ggml_backend_buffer_is_host (buffer=0x0) at /devel/tools/llama.cpp/ggml/src/ggml-backend.cpp:170
170         return ggml_backend_buft_is_host(ggml_backend_buffer_get_type(buffer));
#8  0x000070552c07a114 in llm_graph_input_rs::set_input (this=0x5f11bdf6aea0, ubatch=0x5f11be011300) at /devel/tools/llama.cpp/src/llama-graph.cpp:241
241             GGML_ASSERT(ggml_backend_buffer_is_host(s_copy->buffer));
#9  0x000070552c07b03c in llm_graph_input_mem_hybrid::set_input (this=0x5f11bdf6aee0, ubatch=0x5f11be011300) at /devel/tools/llama.cpp/src/llama-graph.cpp:437
437         inp_rs->set_input(ubatch);
#10 0x000070552c07b549 in llm_graph_result::set_inputs (this=0x5f11be01ddf0, ubatch=0x5f11be011300) at /devel/tools/llama.cpp/src/llama-graph.cpp:480
480             input->set_input(ubatch);
#11 0x000070552c01ddb3 in llama_context::process_ubatch (this=0x5f11c05b5b50, ubatch=..., gtype=LLM_GRAPH_TYPE_DECODER, mctx=0x5f11be00ff00, ret=@0x7fff74d22ea4: 538976288) at /devel/tools/llama.cpp/src/llama-context.cpp:779
779             res->set_inputs(&ubatch);
#12 0x000070552c01f367 in llama_context::decode (this=0x5f11c05b5b50, batch_inp=...) at /devel/tools/llama.cpp/src/llama-context.cpp:1088
1088            const auto * res = process_ubatch(ubatch, LLM_GRAPH_TYPE_DECODER, mctx.get(), status);
#13 0x000070552c025e49 in llama_decode (ctx=0x5f11c05b5b50, batch=...) at /devel/tools/llama.cpp/src/llama-context.cpp:2726
2726        const int ret = ctx->decode(batch);
#14 0x00005f11a2021559 in common_init_from_params (params=...) at /devel/tools/llama.cpp/common/common.cpp:1066
1066                llama_decode(lctx, llama_batch_get_one(tmp.data(), std::min(tmp.size(), (size_t) params.n_batch)));
#15 0x00005f11a1e4a3c0 in main (argc=7, argv=0x7fff74d25968) at /devel/tools/llama.cpp/tools/main/main.cpp:140
140         common_init_result llama_init = common_init_from_params(params);

I'll try to merge the op into the ggml_delta_net function call as @ngxson suggested.

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CISC commented Sep 19, 2025

  1. A full repro with the error it's raising would definitely help debug

Running llama-cli -m reference/qwen3_next_500m/Qwen3_Next_500M-8x417M-BF16.gguf -ngl 999 -p "Who are " yields this weird memory error:

...
#6  0x000070552bb6091e in ggml_backend_buffer_get_type (buffer=0x0) at /devel/tools/llama.cpp/ggml/src/ggml-backend.cpp:189
189         GGML_ASSERT(buffer);
#7  0x000070552bb6080e in ggml_backend_buffer_is_host (buffer=0x0) at /devel/tools/llama.cpp/ggml/src/ggml-backend.cpp:170
170         return ggml_backend_buft_is_host(ggml_backend_buffer_get_type(buffer));
...

The backend buffer is NULL.

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ngxson commented Sep 19, 2025

#9  0x000070552c07b03c in llm_graph_input_mem_hybrid::set_input (this=0x5f11bdf6aee0, ubatch=0x5f11be011300) at /devel/tools/llama.cpp/src/llama-graph.cpp:437
437         inp_rs->set_input(ubatch);

The model doesn't seem to have any recurrence layers. This makes the set input fails due to input node not being present in cgraph.

I'll try to merge the op into the ggml_delta_net function call as @ngxson suggested.

Hmm I think I said the reverse: not to merge it but make the op simple

I feel like this op can be implemented using other ggml ops like mul, mul_mat, sum. Which part of the calculation do you think that can't be constructed using existing ops?

This is the more important question: should we try to implement it using existing ops, or add a new op and spend even more time to optimize it cross all backends?

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pwilkin commented Sep 19, 2025

Now this is an error I haven't expected to encounter:

GGML_ABORT("not enough space in the context's memory pool");

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pwilkin commented Sep 19, 2025

The model doesn't seem to have any recurrence layers. This makes the set input fails due to input node not being present in cgraph.

How do I allocate the memory for the linear layers then? I seem to have misunderstood how build_inp_mem_hybrid() works...

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@pwilkin any chance to buy you a coffee?(Paterson etc.) so community able to donate for your efforts. Thank you!

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pwilkin commented Sep 19, 2025

@pwilkin any chance to buy you a coffee?(Paterson etc.) so community able to donate for your efforts. Thank you!

Added a buymeacoffee link to my profile (do consider first funding the Llama.cpp project itself, though!)

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ServeurpersoCom commented Sep 19, 2025

@pwilkin any chance to buy you a coffee?(Paterson etc.) so community able to donate for your efforts. Thank you!

Added a buymeacoffee link to my profile (do consider first funding the Llama.cpp project itself, though!)

I send a coffee also.

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ngxson commented Sep 20, 2025

GGML_ABORT("not enough space in the context's memory pool");

Probably there are too many nodes on cgraph, try increasing the limit via llama_context::graph_max_nodes()

Comment on lines 19054 to 19056
Qcur = ggml_reshape_3d(ctx0, ggml_cont(ctx0, Qcur), n_embd_head, hparams.n_head(il), n_tokens);
Kcur = ggml_reshape_3d(ctx0, ggml_cont(ctx0, Kcur), n_embd_head, hparams.n_head_kv(il), n_tokens);
Vcur = ggml_reshape_3d(ctx0, ggml_cont(ctx0, Vcur), n_embd_head, hparams.n_head_kv(il), n_tokens);
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these ggml_cont can be removed if Q/gate are separated. ggml_cont is not recommended when dealing with big tensors

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Actually none of these need ggml_cont, Q is 3D already, Q/K are RoPEd so can be views and V can also be a 3D view now.

Edit: sorry, not quite true about V, only if QKV is fused, the weird gate fuse threw me off. Nevertheless, K/V are already contiguous at this point.

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the problem is that Q is non-contiguous and ggml_rope(_ext) does not work very well with non-cont tensors, it's still buggy on certain backends

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the problem is that Q is non-contiguous and ggml_rope(_ext) does not work very well with non-cont tensors, it's still buggy on certain backends

Are you sure? AFAIK those issues are fixed.

Edit: Also, if there still are issues they will never get fixed if we work around them. :)

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the problem is that Q is non-contiguous and ggml_rope(_ext) does not work very well with non-cont tensors, it's still buggy on certain backends

I think all of these cases are fixed now.

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This was an impl of 2D rope that relies on ggml_view: https://github.com/ngxson/ggml-easy/blob/f56e5e499b1f21a4aae73010e9d9582840428457/demo/2d-rope.cpp

It works on CPU and Metal, but doesn't work on CUDA/Vulkan. Couldn't tested on other backends, but feel free to make a PR to address this issue.

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yes that seems to work. sorry @pwilkin you will need to manually revert the change where I split Q/gate. the tensor shape for Q will be:

layer.wq = create_tensor(tn(LLM_TENSOR_ATTN_Q, "weight", i), { n_embd, n_embd_head_k * n_head * 2 }, 0);

layer.ssm_a = create_tensor(tn(LLM_TENSOR_SSM_A, i), { hparams.ssm_dt_rank }, 0);
layer.ssm_beta_alpha = create_tensor(tn(LLM_TENSOR_SSM_BETA_ALPHA, "weight", i), { n_embd, ba_projection_size }, 0);
layer.ssm_norm = create_tensor(tn(LLM_TENSOR_SSM_NORM, "weight", i), { head_v_dim }, 0);
layer.ssm_out = create_tensor(tn(LLM_TENSOR_SSM_OUT, "weight", i), { n_ff, n_embd }, 0);
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Shape of LLM_TENSOR_ATTN_Q and LLM_TENSOR_SSM_OUT should not contain n_ff

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ngxson commented Sep 20, 2025

^ proposed fix for the 3 comments above: 46110e0

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pwilkin commented Sep 20, 2025

@ngxson Thanks, scale_bias was one op I was missing in my endeavors :>

I got an LLM to rewrite the internal delta into tensor logic. After a day of manually fixing that crap, I think I understand it enough to rewrite it myself ;)

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ngxson commented Sep 20, 2025

Honestly I would prefer taking time to understand the mamba/ssm implementation then writing the code manually. Code written by LLM are mostly attempts for 1-to-1 translation from pytorch --> GGML which looks quite confusing

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pwilkin commented Sep 20, 2025

Honestly I would prefer taking time to understand the mamba/ssm implementation then writing the code manually. Code written by LLM are mostly attempts for 1-to-1 translation from pytorch --> GGML which looks quite confusing

Yeah, for me getting a rough outline then going over it manually is the best way to learn :)

I tried the "one-to-one" approach and ended up with a graph that wouldn't fit in 16 GB of RAM for a 500M model...

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pwilkin commented Sep 20, 2025

Aight, I cleaned up the main graph calculation, now I have to figure out how to include conv_states_all in my delta_net function in order to not get the memory error.

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M3l-Idk commented Nov 14, 2025

Whats going on?

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pwilkin commented Nov 14, 2025

Whats going on?

Updated the main post. Next stage will be to rebase it on top of current master with the operators added in and look for a solution to the chunking problem.

@ggerganov what would you think about an operation CHUNK that takes a separate graph and performs the graph operations repeatedly on an input tensor? I don't see another way out of the conundrum with the hybrid models which on one way require chunking due to the O(n^3) solve operations and preventing graph overflow on the other hand...

@pwilkin pwilkin requested review from CISC and ggerganov November 14, 2025 18:10
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pwilkin commented Nov 14, 2025

Lo and behold, I have performed a CLEANUP and this nightmare of a PR is no more, elegant clean version has been uploaded :>

@github-actions github-actions bot added the model Model specific label Nov 14, 2025
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with this pr I get:

llama_model_load: error loading model: error loading model hyperparameters: unsupported model architecture
llama_model_load_from_file_impl: failed to load model
common_init_from_params: failed to load model 'lefromage/Qwen__Qwen3-Next-80B-A3B-Instruct-Q4_K_M.gguf', try reducing --n-gpu-layers if you're running out of VRAM
srv    load_model: failed to load model, 'lefromage/Qwen__Qwen3-Next-80B-A3B-Instruct-Q4_K_M.gguf'
srv    operator(): operator(): cleaning up before exit...
main: exiting due to model loading error

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this PR is missing break; in llama-model.cpp:2238, at end of case LLM_ARCH_QWEN3NEXT:

diff --git a/src/llama-model.cpp b/src/llama-model.cpp
index 3e49060dd..35b82da41 100644
--- a/src/llama-model.cpp
+++ b/src/llama-model.cpp
@@ -2235,7 +2235,7 @@ void llama_model::load_hparams(llama_model_loader & ml) {
case 80: type = LLM_TYPE_80B_A3B; break;
default: type = LLM_TYPE_UNKNOWN;
}

  •        }
    
  •        } break;
       default: throw std::runtime_error("unsupported model architecture");
    
    }

but then other error:

load_tensors: loading model tensors, this can take a while... (mmap = false)
llama_model_load: error loading model: missing tensor info mapping for blk.0.ssm_ba.weight
llama_model_load_from_file_impl: failed to load model

pwilkin and others added 3 commits November 16, 2025 21:46
Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>
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pwilkin commented Nov 17, 2025

I've cleaned up the obvious bugs but there are some regressions, not sure why at the moment, will debug to find out.

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pwilkin commented Nov 17, 2025

@ggerganov this seems like a bug, and a pretty ugly one at that:

ggml_debug:        g_cum_last_view-0 = (f32)       VIEW(g_cumsum-0 (transposed) (cont){1, 4, 2, 1}, }) = {1, 1, 2, 1}
                                     [
                                      [
                                       [     -6.1265],
                                      ],
                                      [
                                       [    -73.0931],
                                      ],
                                     ]
                                     sum = -79.219696
ggml_debug:             g_cum_last-0 = (f32)       CONT(g_cum_last_view-0{1, 1, 2, 1}, }) = {1, 1, 2, 1}
                                     [
                                      [
                                       [     -6.1265],
                                      ],
                                      [
                                       [    -17.9307],
                                      ],
                                     ]
                                     sum = -24.057196

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pwilkin commented Nov 17, 2025

Actually, tested on CPU and this is CUDA-specific. @am17an maybe you'd want to take a look? It seems in this specific case CONT is not behaving well.

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pwilkin commented Nov 17, 2025

Okay, got it. See #17332

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pwilkin commented Nov 17, 2025

With the CUDA fix the model has been restored to its righteous glory:

> Hello model!
Hello! 😊 How can I help you today? Whether you have a question, need help with a task, or just want to chat—I'm here for you!

> Write me a nice quicksort in Haskell.
Absolutely! Here’s a clean, idiomatic, and *nice* quicksort in Haskell — classic, elegant, and beautifully functional:

quicksort :: Ord a => [a] -> [a]
quicksort [] = []
quicksort (x:xs) =
    quicksort smaller ++ [x] ++ quicksort larger
  where
    smaller = [y | y <- xs, y <= x]
    larger  = [y | y <- xs, y > x]

### Why it’s nice:
- **Concise**: Just 4 lines of logic.
- **Readable**: The intent is crystal clear — partition, recurse, concatenate.
- **Idiomatic**: Uses list comprehensions and pattern matching, which are staples of Haskell.
- **Polymorphic**: Works on any type that supports ordering (`Ord a`).
- **Pure & immutable**: No side effects — pure functional style.

### Example usage:
main :: IO ()
main = do
    print $ quicksort [3, 6, 8, 4, 2, 5, 1]  -- [1,2,3,4,5,6,8]
    print $ quicksort "haskell"              -- "aehklls"

> 💡 *Note: This isn’t the most efficient in practice (due to list concatenation and extra passes), but it’s perfect for learning and showcases Haskell’s beauty.*

Want a faster, tail-recursive, or in-place version? (Even though “in-place” isn’t really a thing in pure Haskell 😉) — just ask!

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Feature Request: Qwen3-Next support