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Re-set default n_batch #17594

Merged
merged 2 commits into from
Mar 29, 2024
Merged

Re-set default n_batch #17594

merged 2 commits into from
Mar 29, 2024

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rlancemartin
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@rlancemartin rlancemartin commented Feb 15, 2024

When testing Nomic embeddings --

from langchain_community.embeddings import LlamaCppEmbeddings
embd_model_path = "/Users/rlm/Desktop/Code/llama.cpp/models/nomic-embd/nomic-embed-text-v1.Q4_K_S.gguf"
embd_lc = LlamaCppEmbeddings(model_path=embd_model_path)
embedding_lc = embd_lc.embed_query(query)

We were seeing this error for strings > a certain size --

File ~/miniforge3/envs/llama2/lib/python3.9/site-packages/llama_cpp/llama.py:827, in Llama.embed(self, input, normalize, truncate, return_count)
    824     s_sizes = []
    826 # add to batch
--> 827 self._batch.add_sequence(tokens, len(s_sizes), False)
    828 t_batch += n_tokens
    829 s_sizes.append(n_tokens)

File ~/miniforge3/envs/llama2/lib/python3.9/site-packages/llama_cpp/_internals.py:542, in _LlamaBatch.add_sequence(self, batch, seq_id, logits_all)
    540 self.batch.token[j] = batch[i]
    541 self.batch.pos[j] = i
--> 542 self.batch.seq_id[j][0] = seq_id
    543 self.batch.n_seq_id[j] = 1
    544 self.batch.logits[j] = logits_all

ValueError: NULL pointer access

The default n_batch of llama-cpp-python's Llama is 512 but we were explicitly setting it to 8.

These need to be set to equal for embedding models.

  • The embedding.cpp example has an assertion to make sure these are always equal.
  • Apparently this is not being done properly in llama-cpp-python.

With n_batch set to 8, if more than 8 tokens are passed the batch runs out of space and it crashes.

This also explains why the CPU compute buffer size was small:

raw client with default n_batch=512

llama_new_context_with_model:        CPU input buffer size   =     3.51 MiB
llama_new_context_with_model:        CPU compute buffer size =    21.00 MiB

langchain with n_batch=8

llama_new_context_with_model:        CPU input buffer size   =     0.04 MiB
llama_new_context_with_model:        CPU compute buffer size =     0.33 MiB

We can work around this by passing n_batch=512, but this will not be obvious to some users:

    embedding = LlamaCppEmbeddings(model_path=embd_model_path,
                                   n_batch=512)

From discussion w/ @cebtenzzre. Related:

abetlen/llama-cpp-python#1189

@dosubot dosubot bot added the size:XS This PR changes 0-9 lines, ignoring generated files. label Feb 15, 2024
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@dosubot dosubot bot added Ɑ: embeddings Related to text embedding models module 🤖:bug Related to a bug, vulnerability, unexpected error with an existing feature labels Feb 15, 2024
@dosubot dosubot bot added the lgtm PR looks good. Use to confirm that a PR is ready for merging. label Mar 29, 2024
@baskaryan baskaryan enabled auto-merge (squash) March 29, 2024 00:44
@baskaryan baskaryan merged commit 12843f2 into master Mar 29, 2024
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@baskaryan baskaryan deleted the rlm/llama-embd branch March 29, 2024 00:47
gkorland pushed a commit to FalkorDB/langchain that referenced this pull request Mar 30, 2024
…in-ai#17594)

When testing Nomic embeddings --
```
from langchain_community.embeddings import LlamaCppEmbeddings
embd_model_path = "/Users/rlm/Desktop/Code/llama.cpp/models/nomic-embd/nomic-embed-text-v1.Q4_K_S.gguf"
embd_lc = LlamaCppEmbeddings(model_path=embd_model_path)
embedding_lc = embd_lc.embed_query(query)
```

We were seeing this error for strings > a certain size -- 
```
File ~/miniforge3/envs/llama2/lib/python3.9/site-packages/llama_cpp/llama.py:827, in Llama.embed(self, input, normalize, truncate, return_count)
    824     s_sizes = []
    826 # add to batch
--> 827 self._batch.add_sequence(tokens, len(s_sizes), False)
    828 t_batch += n_tokens
    829 s_sizes.append(n_tokens)

File ~/miniforge3/envs/llama2/lib/python3.9/site-packages/llama_cpp/_internals.py:542, in _LlamaBatch.add_sequence(self, batch, seq_id, logits_all)
    540 self.batch.token[j] = batch[i]
    541 self.batch.pos[j] = i
--> 542 self.batch.seq_id[j][0] = seq_id
    543 self.batch.n_seq_id[j] = 1
    544 self.batch.logits[j] = logits_all

ValueError: NULL pointer access
```

The default `n_batch` of llama-cpp-python's Llama is `512` but we were
explicitly setting it to `8`.
 
These need to be set to equal for embedding models. 
* The embedding.cpp example has an assertion to make sure these are
always equal.
* Apparently this is not being done properly in llama-cpp-python.

With `n_batch` set to 8, if more than 8 tokens are passed the batch runs
out of space and it crashes.

This also explains why the CPU compute buffer size was small:

raw client with default `n_batch=512`
```
llama_new_context_with_model:        CPU input buffer size   =     3.51 MiB
llama_new_context_with_model:        CPU compute buffer size =    21.00 MiB
```
langchain with `n_batch=8`
```
llama_new_context_with_model:        CPU input buffer size   =     0.04 MiB
llama_new_context_with_model:        CPU compute buffer size =     0.33 MiB
```

We can work around this by passing `n_batch=512`, but this will not be
obvious to some users:
```
    embedding = LlamaCppEmbeddings(model_path=embd_model_path,
                                   n_batch=512)
```

From discussion w/ @cebtenzzre. Related:

abetlen/llama-cpp-python#1189

Co-authored-by: Bagatur <[email protected]>
hinthornw pushed a commit that referenced this pull request Apr 26, 2024
When testing Nomic embeddings --
```
from langchain_community.embeddings import LlamaCppEmbeddings
embd_model_path = "/Users/rlm/Desktop/Code/llama.cpp/models/nomic-embd/nomic-embed-text-v1.Q4_K_S.gguf"
embd_lc = LlamaCppEmbeddings(model_path=embd_model_path)
embedding_lc = embd_lc.embed_query(query)
```

We were seeing this error for strings > a certain size -- 
```
File ~/miniforge3/envs/llama2/lib/python3.9/site-packages/llama_cpp/llama.py:827, in Llama.embed(self, input, normalize, truncate, return_count)
    824     s_sizes = []
    826 # add to batch
--> 827 self._batch.add_sequence(tokens, len(s_sizes), False)
    828 t_batch += n_tokens
    829 s_sizes.append(n_tokens)

File ~/miniforge3/envs/llama2/lib/python3.9/site-packages/llama_cpp/_internals.py:542, in _LlamaBatch.add_sequence(self, batch, seq_id, logits_all)
    540 self.batch.token[j] = batch[i]
    541 self.batch.pos[j] = i
--> 542 self.batch.seq_id[j][0] = seq_id
    543 self.batch.n_seq_id[j] = 1
    544 self.batch.logits[j] = logits_all

ValueError: NULL pointer access
```

The default `n_batch` of llama-cpp-python's Llama is `512` but we were
explicitly setting it to `8`.
 
These need to be set to equal for embedding models. 
* The embedding.cpp example has an assertion to make sure these are
always equal.
* Apparently this is not being done properly in llama-cpp-python.

With `n_batch` set to 8, if more than 8 tokens are passed the batch runs
out of space and it crashes.

This also explains why the CPU compute buffer size was small:

raw client with default `n_batch=512`
```
llama_new_context_with_model:        CPU input buffer size   =     3.51 MiB
llama_new_context_with_model:        CPU compute buffer size =    21.00 MiB
```
langchain with `n_batch=8`
```
llama_new_context_with_model:        CPU input buffer size   =     0.04 MiB
llama_new_context_with_model:        CPU compute buffer size =     0.33 MiB
```

We can work around this by passing `n_batch=512`, but this will not be
obvious to some users:
```
    embedding = LlamaCppEmbeddings(model_path=embd_model_path,
                                   n_batch=512)
```

From discussion w/ @cebtenzzre. Related:

abetlen/llama-cpp-python#1189

Co-authored-by: Bagatur <[email protected]>
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