Vulkan/AMDVLK: Device memory allocation fails when single compute buffer > ~2 GiB (same model works on RADV) #413
Description
Problem description & steps to reproduce
There is an open issue on llama.ccp (ggml-org/llama.cpp#15054) for a bug on systems using AMDVLK. Some GGUF models that load and run under RADV fail during model/context initialization in llama.cpp’s Vulkan backend with VK_ERROR_OUT_OF_DEVICE_MEMORY:
ggml_vulkan: Device memory allocation of size 2819260416 failed.
ggml_vulkan: Requested buffer size exceeds device memory allocation limit: ErrorOutOfDeviceMemory
alloc_tensor_range: failed to allocate Vulkan0 buffer of size 2819260416
The failures correlate with a single Vulkan allocation (the ggml_vulkan compute buffer) exceeding the driver’s per-allocation cap VkPhysicalDeviceLimits::maxMemoryAllocationSize. On the affected machine this is 0x80000000 (≈2 GiB). The backend occasionally needs to request ~2.0–2.6 GiB for this buffer, which succeeds on RADV but is rejected by AMDVLK, indicating the issue is the per-allocation limit, not total VRAM.
The following response from the original llama.cpp issue made me think it was a good idea to raise this here:
Yes, the driver sets a maximum allocation size and a maximum buffer size limit. This is 2GB on amdvlk and the proprietary AMD drivers, and 4GB on RADV. We have no control over this, I don't know why AMD keeps the limit below the theoretical maximum that all the other major Vulkan drivers use.
Example (Gemma 3 27B BF16)
For example, this happens with gemma-3-27b-it-BF16/gemma-3-27b-it-BF16 (https://huggingface.co/unsloth/gemma-3-27b-it-GGUF):
$ llama-cli -ngl 99 -fa -m models/gemma-3-27b-it-BF16/gemma-3-27b-it-BF16-00001-of-00002.gguf
ggml_vulkan: Found 1 Vulkan devices:
ggml_vulkan: 0 = Radeon 8060S Graphics (AMD open-source driver) | uma: 1 | fp16: 1 | bf16: 0 | warp size: 64 | shared memory: 32768 | int dot: 1 | matrix cores: KHR_coopmat
build: 6060 (9c35706b) with cc (GCC) 15.1.1 20250719 (Red Hat 15.1.1-5) for x86_64-redhat-linux
main: llama backend init
main: load the model and apply lora adapter, if any
llama_model_load_from_file_impl: using device Vulkan0 (Radeon 8060S Graphics) - 85720 MiB free
llama_model_loader: additional 1 GGUFs metadata loaded.
llama_model_loader: loaded meta data with 39 key-value pairs and 808 tensors from models/gemma-3-27b-it-BF16/gemma-3-27b-it-BF16-00001-of-00002.gguf (version GGUF V3 (latest))
llama_model_loader: Dumping metadata keys/values. Note: KV overrides do not apply in this output.
llama_model_loader: - kv 0: general.architecture str = gemma3
llama_model_loader: - kv 1: general.type str = model
llama_model_loader: - kv 2: general.name str = Gemma-3-27B-It
llama_model_loader: - kv 3: general.finetune str = it
llama_model_loader: - kv 4: general.basename str = Gemma-3-27B-It
llama_model_loader: - kv 5: general.quantized_by str = Unsloth
llama_model_loader: - kv 6: general.size_label str = 27B
llama_model_loader: - kv 7: general.repo_url str = https://huggingface.co/unsloth
llama_model_loader: - kv 8: gemma3.context_length u32 = 131072
llama_model_loader: - kv 9: gemma3.embedding_length u32 = 5376
llama_model_loader: - kv 10: gemma3.block_count u32 = 62
llama_model_loader: - kv 11: gemma3.feed_forward_length u32 = 21504
llama_model_loader: - kv 12: gemma3.attention.head_count u32 = 32
llama_model_loader: - kv 13: gemma3.attention.layer_norm_rms_epsilon f32 = 0.000001
llama_model_loader: - kv 14: gemma3.attention.key_length u32 = 128
llama_model_loader: - kv 15: gemma3.attention.value_length u32 = 128
llama_model_loader: - kv 16: general.file_type u32 = 32
llama_model_loader: - kv 17: gemma3.rope.freq_base f32 = 1000000.000000
llama_model_loader: - kv 18: gemma3.attention.sliding_window u32 = 1024
llama_model_loader: - kv 19: gemma3.attention.head_count_kv u32 = 16
llama_model_loader: - kv 20: gemma3.rope.scaling.type str = linear
llama_model_loader: - kv 21: gemma3.rope.scaling.factor f32 = 8.000000
llama_model_loader: - kv 22: general.quantization_version u32 = 2
llama_model_loader: - kv 23: tokenizer.ggml.model str = llama
llama_model_loader: - kv 24: tokenizer.ggml.pre str = default
llama_model_loader: - kv 25: tokenizer.ggml.tokens arr[str,262208] = ["<pad>", "<eos>", "<bos>", "<unk>", ...
llama_model_loader: - kv 26: tokenizer.ggml.scores arr[f32,262208] = [-1000.000000, -1000.000000, -1000.00...
llama_model_loader: - kv 27: tokenizer.ggml.token_type arr[i32,262208] = [3, 3, 3, 3, 3, 4, 3, 3, 3, 3, 3, 3, ...
llama_model_loader: - kv 28: tokenizer.ggml.bos_token_id u32 = 2
llama_model_loader: - kv 29: tokenizer.ggml.eos_token_id u32 = 106
llama_model_loader: - kv 30: tokenizer.ggml.unknown_token_id u32 = 3
llama_model_loader: - kv 31: tokenizer.ggml.padding_token_id u32 = 0
llama_model_loader: - kv 32: tokenizer.ggml.add_bos_token bool = true
llama_model_loader: - kv 33: tokenizer.ggml.add_eos_token bool = false
llama_model_loader: - kv 34: tokenizer.chat_template str = {{ bos_token }}\n{%- if messages[0]['r...
llama_model_loader: - kv 35: tokenizer.ggml.add_space_prefix bool = false
llama_model_loader: - kv 36: split.no u16 = 0
llama_model_loader: - kv 37: split.count u16 = 2
llama_model_loader: - kv 38: split.tensors.count i32 = 808
llama_model_loader: - type f32: 373 tensors
llama_model_loader: - type bf16: 435 tensors
print_info: file format = GGUF V3 (latest)
print_info: file type = BF16
print_info: file size = 50.31 GiB (16.00 BPW)
load: special tokens cache size = 6415
load: token to piece cache size = 1.9446 MB
print_info: arch = gemma3
print_info: vocab_only = 0
print_info: n_ctx_train = 131072
print_info: n_embd = 5376
print_info: n_layer = 62
print_info: n_head = 32
print_info: n_head_kv = 16
print_info: n_rot = 128
print_info: n_swa = 1024
print_info: is_swa_any = 1
print_info: n_embd_head_k = 128
print_info: n_embd_head_v = 128
print_info: n_gqa = 2
print_info: n_embd_k_gqa = 2048
print_info: n_embd_v_gqa = 2048
print_info: f_norm_eps = 0.0e+00
print_info: f_norm_rms_eps = 1.0e-06
print_info: f_clamp_kqv = 0.0e+00
print_info: f_max_alibi_bias = 0.0e+00
print_info: f_logit_scale = 0.0e+00
print_info: f_attn_scale = 7.7e-02
print_info: n_ff = 21504
print_info: n_expert = 0
print_info: n_expert_used = 0
print_info: causal attn = 1
print_info: pooling type = 0
print_info: rope type = 2
print_info: rope scaling = linear
print_info: freq_base_train = 1000000.0
print_info: freq_scale_train = 0.125
print_info: n_ctx_orig_yarn = 131072
print_info: rope_finetuned = unknown
print_info: model type = 27B
print_info: model params = 27.01 B
print_info: general.name = Gemma-3-27B-It
print_info: vocab type = SPM
print_info: n_vocab = 262208
print_info: n_merges = 0
print_info: BOS token = 2 '<bos>'
print_info: EOS token = 106 '<end_of_turn>'
print_info: EOT token = 106 '<end_of_turn>'
print_info: UNK token = 3 '<unk>'
print_info: PAD token = 0 '<pad>'
print_info: LF token = 248 '<0x0A>'
print_info: EOG token = 106 '<end_of_turn>'
print_info: max token length = 48
load_tensors: loading model tensors, this can take a while... (mmap = true)
ggml_vulkan: Device memory allocation of size 2819260416 failed.
ggml_vulkan: Requested buffer size exceeds device memory allocation limit: ErrorOutOfDeviceMemory
alloc_tensor_range: failed to allocate Vulkan0 buffer of size 2819260416
llama_model_load: error loading model: unable to allocate Vulkan0 buffer
llama_model_load_from_file_impl: failed to load model
common_init_from_params: failed to load model 'models/gemma-3-27b-it-BF16/gemma-3-27b-it-BF16-00001-of-00002.gguf'
main: error: unable to load model
However, with RADV the model loads just fine:
toolbox enter llama-vulkan-radv
⬢ [kyuz0@toolbx ~]$ llama-cli -ngl 99 -fa -m models/gemma-3-27b-it-BF16/gemma-3-27b-it-BF16-00001-of-00002.gguf
ggml_vulkan: Found 1 Vulkan devices:
ggml_vulkan: 0 = Radeon 8060S Graphics (RADV GFX1151) (radv) | uma: 1 | fp16: 1 | bf16: 0 | warp size: 64 | shared memory: 65536 | int dot: 1 | matrix cores: KHR_coopmat
build: 6040 (66625a59) with cc (GCC) 15.1.1 20250719 (Red Hat 15.1.1-5) for x86_64-redhat-linux
main: llama backend init
main: load the model and apply lora adapter, if any
llama_model_load_from_file_impl: using device Vulkan0 (Radeon 8060S Graphics (RADV GFX1151)) - 87722 MiB free
llama_model_loader: additional 1 GGUFs metadata loaded.
llama_model_loader: loaded meta data with 39 key-value pairs and 808 tensors from models/gemma-3-27b-it-BF16/gemma-3-27b-it-BF16-00001-of-00002.gguf (version GGUF V3 (latest))
llama_model_loader: Dumping metadata keys/values. Note: KV overrides do not apply in this output.
llama_model_loader: - kv 0: general.architecture str = gemma3
llama_model_loader: - kv 1: general.type str = model
llama_model_loader: - kv 2: general.name str = Gemma-3-27B-It
llama_model_loader: - kv 3: general.finetune str = it
llama_model_loader: - kv 4: general.basename str = Gemma-3-27B-It
llama_model_loader: - kv 5: general.quantized_by str = Unsloth
llama_model_loader: - kv 6: general.size_label str = 27B
llama_model_loader: - kv 7: general.repo_url str = https://huggingface.co/unsloth
llama_model_loader: - kv 8: gemma3.context_length u32 = 131072
llama_model_loader: - kv 9: gemma3.embedding_length u32 = 5376
llama_model_loader: - kv 10: gemma3.block_count u32 = 62
llama_model_loader: - kv 11: gemma3.feed_forward_length u32 = 21504
llama_model_loader: - kv 12: gemma3.attention.head_count u32 = 32
llama_model_loader: - kv 13: gemma3.attention.layer_norm_rms_epsilon f32 = 0.000001
llama_model_loader: - kv 14: gemma3.attention.key_length u32 = 128
llama_model_loader: - kv 15: gemma3.attention.value_length u32 = 128
llama_model_loader: - kv 16: general.file_type u32 = 32
llama_model_loader: - kv 17: gemma3.rope.freq_base f32 = 1000000.000000
llama_model_loader: - kv 18: gemma3.attention.sliding_window u32 = 1024
llama_model_loader: - kv 19: gemma3.attention.head_count_kv u32 = 16
llama_model_loader: - kv 20: gemma3.rope.scaling.type str = linear
llama_model_loader: - kv 21: gemma3.rope.scaling.factor f32 = 8.000000
llama_model_loader: - kv 22: general.quantization_version u32 = 2
llama_model_loader: - kv 23: tokenizer.ggml.model str = llama
llama_model_loader: - kv 24: tokenizer.ggml.pre str = default
llama_model_loader: - kv 25: tokenizer.ggml.tokens arr[str,262208] = ["<pad>", "<eos>", "<bos>", "<unk>", ...
llama_model_loader: - kv 26: tokenizer.ggml.scores arr[f32,262208] = [-1000.000000, -1000.000000, -1000.00...
llama_model_loader: - kv 27: tokenizer.ggml.token_type arr[i32,262208] = [3, 3, 3, 3, 3, 4, 3, 3, 3, 3, 3, 3, ...
llama_model_loader: - kv 28: tokenizer.ggml.bos_token_id u32 = 2
llama_model_loader: - kv 29: tokenizer.ggml.eos_token_id u32 = 106
llama_model_loader: - kv 30: tokenizer.ggml.unknown_token_id u32 = 3
llama_model_loader: - kv 31: tokenizer.ggml.padding_token_id u32 = 0
llama_model_loader: - kv 32: tokenizer.ggml.add_bos_token bool = true
llama_model_loader: - kv 33: tokenizer.ggml.add_eos_token bool = false
llama_model_loader: - kv 34: tokenizer.chat_template str = {{ bos_token }}\n{%- if messages[0]['r...
llama_model_loader: - kv 35: tokenizer.ggml.add_space_prefix bool = false
llama_model_loader: - kv 36: split.no u16 = 0
llama_model_loader: - kv 37: split.count u16 = 2
llama_model_loader: - kv 38: split.tensors.count i32 = 808
llama_model_loader: - type f32: 373 tensors
llama_model_loader: - type bf16: 435 tensors
print_info: file format = GGUF V3 (latest)
print_info: file type = BF16
print_info: file size = 50.31 GiB (16.00 BPW)
load: special tokens cache size = 6415
load: token to piece cache size = 1.9446 MB
print_info: arch = gemma3
print_info: vocab_only = 0
print_info: n_ctx_train = 131072
print_info: n_embd = 5376
print_info: n_layer = 62
print_info: n_head = 32
print_info: n_head_kv = 16
print_info: n_rot = 128
print_info: n_swa = 1024
print_info: is_swa_any = 1
print_info: n_embd_head_k = 128
print_info: n_embd_head_v = 128
print_info: n_gqa = 2
print_info: n_embd_k_gqa = 2048
print_info: n_embd_v_gqa = 2048
print_info: f_norm_eps = 0.0e+00
print_info: f_norm_rms_eps = 1.0e-06
print_info: f_clamp_kqv = 0.0e+00
print_info: f_max_alibi_bias = 0.0e+00
print_info: f_logit_scale = 0.0e+00
print_info: f_attn_scale = 7.7e-02
print_info: n_ff = 21504
print_info: n_expert = 0
print_info: n_expert_used = 0
print_info: causal attn = 1
print_info: pooling type = 0
print_info: rope type = 2
print_info: rope scaling = linear
print_info: freq_base_train = 1000000.0
print_info: freq_scale_train = 0.125
print_info: n_ctx_orig_yarn = 131072
print_info: rope_finetuned = unknown
print_info: model type = 27B
print_info: model params = 27.01 B
print_info: general.name = Gemma-3-27B-It
print_info: vocab type = SPM
print_info: n_vocab = 262208
print_info: n_merges = 0
print_info: BOS token = 2 '<bos>'
print_info: EOS token = 106 '<end_of_turn>'
print_info: EOT token = 106 '<end_of_turn>'
print_info: UNK token = 3 '<unk>'
print_info: PAD token = 0 '<pad>'
print_info: LF token = 248 '<0x0A>'
print_info: EOG token = 106 '<end_of_turn>'
print_info: max token length = 48
load_tensors: loading model tensors, this can take a while... (mmap = true)
load_tensors: offloading 62 repeating layers to GPU
load_tensors: offloading output layer to GPU
load_tensors: offloaded 63/63 layers to GPU
load_tensors: Vulkan0 model buffer size = 51518.82 MiB
load_tensors: CPU_Mapped model buffer size = 2688.66 MiB
.............................................................................................
llama_context: constructing llama_context
llama_context: non-unified KV cache requires ggml_set_rows() - forcing unified KV cache
llama_context: n_seq_max = 1
llama_context: n_ctx = 4096
llama_context: n_ctx_per_seq = 4096
llama_context: n_batch = 2048
llama_context: n_ubatch = 512
llama_context: causal_attn = 1
llama_context: flash_attn = 1
llama_context: kv_unified = true
llama_context: freq_base = 1000000.0
llama_context: freq_scale = 0.125
llama_context: n_ctx_per_seq (4096) < n_ctx_train (131072) -- the full capacity of the model will not be utilized
llama_context: Vulkan_Host output buffer size = 1.00 MiB
llama_kv_cache_unified_iswa: creating non-SWA KV cache, size = 4096 cells
llama_kv_cache_unified: Vulkan0 KV buffer size = 320.00 MiB
llama_kv_cache_unified: size = 320.00 MiB ( 4096 cells, 10 layers, 1/ 1 seqs), K (f16): 160.00 MiB, V (f16): 160.00 MiB
llama_kv_cache_unified: LLAMA_SET_ROWS=0, using old ggml_cpy() method for backwards compatibility
llama_kv_cache_unified_iswa: creating SWA KV cache, size = 1536 cells
llama_kv_cache_unified: Vulkan0 KV buffer size = 624.00 MiB
llama_kv_cache_unified: size = 624.00 MiB ( 1536 cells, 52 layers, 1/ 1 seqs), K (f16): 312.00 MiB, V (f16): 312.00 MiB
llama_kv_cache_unified: LLAMA_SET_ROWS=0, using old ggml_cpy() method for backwards compatibility
llama_context: Vulkan0 compute buffer size = 522.62 MiB
llama_context: Vulkan_Host compute buffer size = 21.51 MiB
llama_context: graph nodes = 2613
llama_context: graph splits = 2
common_init_from_params: KV cache shifting is not supported for this context, disabling KV cache shifting
common_init_from_params: added <end_of_turn> logit bias = -inf
common_init_from_params: setting dry_penalty_last_n to ctx_size = 4096
common_init_from_params: warming up the model with an empty run - please wait ... (--no-warmup to disable)
main: llama threadpool init, n_threads = 16
main: chat template is available, enabling conversation mode (disable it with -no-cnv)
main: chat template example:
<start_of_turn>user
You are a helpful assistant
Hello<end_of_turn>
<start_of_turn>model
Hi there<end_of_turn>
<start_of_turn>user
How are you?<end_of_turn>
<start_of_turn>model
system_info: n_threads = 16 (n_threads_batch = 16) / 32 | CPU : SSE3 = 1 | SSSE3 = 1 | AVX = 1 | AVX2 = 1 | F16C = 1 | FMA = 1 | BMI2 = 1 | AVX512 = 1 | AVX512_VBMI = 1 | AVX512_VNNI = 1 | LLAMAFILE = 1 | OPENMP = 1 | REPACK = 1 |
main: interactive mode on.
sampler seed: 3532905611
sampler params:
repeat_last_n = 64, repeat_penalty = 1.000, frequency_penalty = 0.000, presence_penalty = 0.000
dry_multiplier = 0.000, dry_base = 1.750, dry_allowed_length = 2, dry_penalty_last_n = 4096
top_k = 40, top_p = 0.950, min_p = 0.050, xtc_probability = 0.000, xtc_threshold = 0.100, typical_p = 1.000, top_n_sigma = -1.000, temp = 0.800
mirostat = 0, mirostat_lr = 0.100, mirostat_ent = 5.000
sampler chain: logits -> logit-bias -> penalties -> dry -> top-n-sigma -> top-k -> typical -> top-p -> min-p -> xtc -> temp-ext -> dist
generate: n_ctx = 4096, n_batch = 2048, n_predict = -1, n_keep = 1
== Running in interactive mode. ==
- Press Ctrl+C to interject at any time.
- Press Return to return control to the AI.
- To return control without starting a new line, end your input with '/'.
- If you want to submit another line, end your input with '\'.
- Not using system message. To change it, set a different value via -sys PROMPT
Vulkaninfo output
$vulkaninfo | grep -i maxMemoryAllocationSize
'DISPLAY' environment variable not set... skipping surface info
maxMemoryAllocationSize = 0xfffffffc
maxMemoryAllocationSize = 0x80000000$vulkaninfo | grep -i maxMemoryAllocationSize
'DISPLAY' environment variable not set... skipping surface info
maxMemoryAllocationSize = 0x80000000Name and Version
llama-cli --version
ggml_vulkan: Found 1 Vulkan devices:
ggml_vulkan: 0 = Radeon 8060S Graphics (AMD open-source driver) | uma: 1 | fp16: 1 | bf16: 0 | warp size: 64 | shared memory: 32768 | int dot: 1 | matrix cores: KHR_coopmat
version: 6060 (9c35706b)
built with cc (GCC) 15.1.1 20250719 (Red Hat 15.1.1-5) for x86_64-redhat-linux
Operating systems
Linux