[V1][Metrics] Deprecate vllm:model_forward/execute_time_milliseconds

Metrics originally added by vllm-project#9659

These seem to be of questionable value relative to the existing
prefill, decode, and inference time metrics. And since they would
be challenging to implement in V1, and they don't conform to the
standard of using seconds as units, let's deprecate them

Signed-off-by: Mark McLoughlin <markmc@redhat.com>

Author: markmc

vllm/engine/metrics.py

@@ -190,18 +190,26 @@ def __init__(self, labelnames: List[str], vllm_config: VllmConfig):
                 "DEPRECATED: use vllm:request_queue_time_seconds instead."),
             labelnames=labelnames,
             buckets=request_latency_buckets)
+
+        # Deprecated in 0.8 - use prefill/decode/inference time metrics
+        # TODO: in 0.9, only enable if show_hidden_metrics=True
         self.histogram_model_forward_time_request = self._histogram_cls(
             name="vllm:model_forward_time_milliseconds",
-            documentation=
-            "Histogram of time spent in the model forward pass in ms.",
+            documentation=(
+                "Histogram of time spent in the model forward pass in ms. "
+                "DEPRECATED: use prefill/decode/inference time metrics instead."
+            ),
             labelnames=labelnames,
             buckets=build_1_2_3_5_8_buckets(3000))
         self.histogram_model_execute_time_request = self._histogram_cls(
             name="vllm:model_execute_time_milliseconds",
-            documentation=
-            "Histogram of time spent in the model execute function in ms.",
+            documentation=(
+                "Histogram of time spent in the model execute function in ms."
+                "DEPRECATED: use prefill/decode/inference time metrics instead."
+            ),
             labelnames=labelnames,
             buckets=build_1_2_3_5_8_buckets(3000))
+
         #   Metadata
         self.histogram_num_prompt_tokens_request = self._histogram_cls(
             name="vllm:request_prompt_tokens",