Latency, Cost, and Error Tracking

Overview

Confident AI lets you track the latency and cost of your LLM calls, which can help you identify inefficiencies in your LLM systems, such as high-cost models or heavy user usage. There are 2 types of cost tracking:

• Manual cost tracking: define the token count and per-token costs manually in code
• Automatic cost tracking: Confident AI infers the token count and per-token costs based on the model

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from deepeval.tracing import observe, update_llm_span
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@observe(
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    type="llm",
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    model="gpt-4o",
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    cost_per_input_token=0.001,
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    cost_per_output_token=0.001
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)
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def generate_response(prompt: str) -> str:
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    output = "Generated response"
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    update_llm_span(
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        input_token_count=10,
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        output_token_count=20,
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    )
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    return output

Setup Cost Tracking

You can either manually configure cost tracking or let Confident AI calculate your costs automatically from the inputs and outputs of your LLM span based on the provided model.

If token-usage and cost data are provided in code, Confident AI computes the cost directly from those values. If not, it attempts to infer the cost from the model, input, and output by following these steps:

1. Verify that the model, input, and output are all available and valid.
2. Select the appropriate tokenizer for the model provider.
3. Count the input and output tokens.
4. Retrieve the per-token pricing from the provider.
5. Compute the total cost.

Automatic Cost Tracking

To set up automatic cost tracking, provide the model in the @observe decorator of your LLM span, and provide the input and output in your LlmAttributes.

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from deepeval.tracing import observe, update_current_span
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@observe(
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    type="llm",
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    model="gpt-4o"
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)
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def generate_response(prompt: str) -> str:
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    output = "Generated response"
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    update_current_span(
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        input=prompt,
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        output=output,
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    )
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    return output

The table below summarizes each available model provider and its corresponding tokenization method.

See the OpenAI documentation, Anthropic documentation, or Google documentation for the most up-to-date pricing and token counting information.

Manual Cost Tracking

To manually set up cost tracking, provide the cost_per_input_token and cost_per_output_token in the @observe decorator of your LLM span, and pass the input and output token counts via LlmAttributes.

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from deepeval.tracing import observe, update_llm_span
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3
@observe(
4
    type="llm",
5
    model="gpt-4o",
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    cost_per_input_token=0.001,
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    cost_per_output_token=0.001
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)
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def generate_response(prompt: str) -> str:
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    output = "Generated response"
11
    update_llm_span(
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        input_token_count=10,
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        output_token_count=20,
14
    )
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    return output

The total cost of this call will be computed as:

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(input_token_count × cost_per_input_token) + (output_token_count × cost_per_output_token)