[Bugfix] Expand quantization method support in perf metrics (#37231)

Signed-off-by: Thillai Chithambaram <thillaichithambaram.a@gmail.com>

tests/v1/metrics/test_perf_metrics.py

@@ -7,6 +7,7 @@ Tests for the analytic estimators in metrics/flops.py.
 import types
 from types import SimpleNamespace
 
+import pytest
 from transformers.models.deepseek_v3.configuration_deepseek_v3 import DeepseekV3Config
 from transformers.models.llama4.configuration_llama4 import (
     Llama4Config,
@@ -21,10 +22,12 @@ from vllm.transformers_utils.model_arch_config_convertor import (
     ModelArchConfigConvertorBase,
 )
 from vllm.v1.metrics.perf import (
+    _QUANT_WEIGHT_BYTE_SIZE,
     AttentionMetrics,
     BaseConfigParser,
     ExecutionContext,
     FfnMetrics,
+    InvalidComponent,
     ModelMetrics,
     ParsedArgs,
     UnembedMetrics,
@@ -905,3 +908,116 @@ def test_attention_per_gpu_heads_not_evenly_divisible():
     assert per_gpu_flops > 0
     assert global_flops > 0
     assert global_flops > per_gpu_flops
+
+
+# INT4 / FP4 quantization methods (weight_byte_size == 0.5)
+_INT4_FP4_METHODS = [m for m, s in _QUANT_WEIGHT_BYTE_SIZE.items() if s == 0.5]
+
+
+@pytest.mark.parametrize("quant_method", _INT4_FP4_METHODS)
+def test_quantization_config_parser_int4_methods(quant_method):
+    """Test quantization parsers with INT4/FP4 methods (0.5 bytes)."""
+
+    class MockQuantConfig:
+        def get_name(self):
+            return quant_method
+
+    hf_config = Qwen3Config(
+        hidden_size=2048,
+        num_attention_heads=16,
+        intermediate_size=8192,
+        num_hidden_layers=1,
+    )
+    vllm_config = create_mock_vllm_config(hf_config, quant_config=MockQuantConfig())
+
+    attn_result = AttentionMetrics.get_parser().parse(vllm_config)
+    assert attn_result.weight_byte_size == 0.5, (
+        f"Expected 0.5 for {quant_method}, got {attn_result.weight_byte_size}"
+    )
+
+    ffn_result = FfnMetrics.get_parser().parse(vllm_config)
+    assert ffn_result.weight_byte_size == 0.5, (
+        f"Expected 0.5 for {quant_method}, got {ffn_result.weight_byte_size}"
+    )
+
+
+# FP8 / INT8 quantization methods (weight_byte_size == 1)
+_FP8_INT8_METHODS = [m for m, s in _QUANT_WEIGHT_BYTE_SIZE.items() if s == 1]
+
+
+@pytest.mark.parametrize("quant_method", _FP8_INT8_METHODS)
+def test_quantization_config_parser_fp8_methods(quant_method):
+    """Test quantization parsers with FP8/INT8 methods (1 byte)."""
+
+    class MockQuantConfig:
+        def get_name(self):
+            return quant_method
+
+    hf_config = Qwen3Config(
+        hidden_size=2048,
+        num_attention_heads=16,
+        intermediate_size=8192,
+        num_hidden_layers=1,
+    )
+    vllm_config = create_mock_vllm_config(hf_config, quant_config=MockQuantConfig())
+
+    attn_result = AttentionMetrics.get_parser().parse(vllm_config)
+    assert attn_result.weight_byte_size == 1, (
+        f"Expected 1 for {quant_method}, got {attn_result.weight_byte_size}"
+    )
+
+    ffn_result = FfnMetrics.get_parser().parse(vllm_config)
+    assert ffn_result.weight_byte_size == 1, (
+        f"Expected 1 for {quant_method}, got {ffn_result.weight_byte_size}"
+    )
+
+
+def test_quantization_config_parser_unknown_method():
+    """Test that an unrecognized quant method raises InvalidComponent."""
+
+    class MockQuantConfig:
+        def get_name(self):
+            return "unknown_quant_method"
+
+    hf_config = Qwen3Config(
+        hidden_size=2048,
+        num_attention_heads=16,
+        intermediate_size=8192,
+        num_hidden_layers=1,
+    )
+    vllm_config = create_mock_vllm_config(hf_config, quant_config=MockQuantConfig())
+
+    with pytest.raises(InvalidComponent):
+        AttentionMetrics.get_parser().parse(vllm_config)
+
+    with pytest.raises(InvalidComponent):
+        FfnMetrics.get_parser().parse(vllm_config)
+
+
+def test_quantized_model_metrics_aggregation():
+    """Test that ModelMetrics works end-to-end with a quantized model config."""
+
+    class MockQuantConfig:
+        def get_name(self):
+            return "gptq"
+
+    hf_config = Qwen3Config(
+        hidden_size=2048,
+        num_attention_heads=16,
+        num_hidden_layers=12,
+        vocab_size=32000,
+        intermediate_size=8192,
+    )
+    vllm_config = create_mock_vllm_config(hf_config, quant_config=MockQuantConfig())
+
+    model_metrics = ModelMetrics(vllm_config)
+    ctx = ExecutionContext.from_single_request(
+        num_tokens=100, context_len=512, is_prefill=True
+    )
+
+    # Should not crash and should produce valid metrics
+    total_flops = model_metrics.get_num_flops(ctx)
+    breakdown = model_metrics.get_num_flops_breakdown(ctx)
+
+    assert total_flops > 0
+    assert total_flops == sum(breakdown.values())