Introducing Mixtral 8x7B: A New Mixture of Experts Architecture

In the ever-evolving field of language models, a new architecture has emerged called Mixtral 8x7B, a part of the Sparse Mixture of Experts (SMoE) framework. This innovative model aims to enhance performance in tasks such as mathematics, code generation, and multilingual understanding, significantly surpassing existing benchmarks.

Overview of Mixtral 8x7B

title: 'Figure 1: Mixture of Experts Layer. Each input vector is assigned to 2 of the 8 experts by a router. The layer’s output is the weighted sum of the outputs of the two selected experts. In Mixtral, an expert is a standard feedforward block as in a vanilla transformer architecture.' — title: 'Figure 1: Mixture of Experts Layer. Each input vector is assigned to 2 of the 8 experts by a router. The layer’s output is the weighted sum of the outputs of the two selected experts. In Mixtral, an expert is a standard feedforward block as ...Read More

Mixtral operates similarly to its predecessor, Mistral 7B, but incorporates several enhancements. The architecture utilizes a router to select two out of eight experts at each layer, allowing it to efficiently process data while containing fewer parameters. Specifically, each token is processed by a network that selects two experts to combine their outputs. While each token can access a large number of parameters—over 478—only 138 are active at any one time, optimizing both capacity and computational efficiency^[1].

The model underwent training with a context size of 32k tokens, enabling significant performance improvements on various established benchmarks. For instance, Mixtral outperforms models like Llama 2 7B and GPT-3.5 on tasks requiring high levels of reasoning and math, showcasing its robust capabilities across categories^[1].

Architectural Insights

title: 'Figure 2: Performance of Mixtral and different Llama models on a wide range of benchmarks. All models were re-evaluated on all metrics with our evaluation pipeline for accurate comparison. Mixtral outperforms or matches Llama 2 70B on all benchmarks. In particular, it is vastly superior in mathematics and code generation.' — title: 'Figure 2: Performance of Mixtral and different Llama models on a wide range of benchmarks. All models were re-evaluated on all metrics with our evaluation pipeline for accurate comparison. Mixtral outperforms or matches Llama 2 70B on all be...Read More

Mixtral leverages a transformer architecture, modifying standard feedforward blocks into a Mixture-of-Experts layer. This transformation permits each input to be weighted according to the selected experts, enhancing the model's adaptability to various tasks^[1]. Through extensive training and tuning, Mixtral exhibits superior performance in areas like reading comprehension and code generation, effectively matching or exceeding model capabilities from other leading systems^[1].

Sparse Mixture of Experts

The advantage of the sparse mixture of experts lies in its structure. Each input is evaluated to determine the most relevant experts, leading to a more efficient allocation of resources. Remarkably, it only requires 138 parameters per token, a fraction of the total parameters available. This setup allows Mixtral to maintain speed while increasing its overall parameter count^[1].

Performance Benchmarks

title: 'Figure 3: Results on MMLU, commonsense reasoning, world knowledge and reading comprehension, math and code for Mistral (7B/8x7B) vs Llama 2 (7B/13B/70B). Mixtral largely outperforms Llama 2 70B on all benchmarks, except on reading comprehension benchmarks while using 5x lower active parameters. It is also vastly superior to Llama 2 70B on code and math.' — title: 'Figure 3: Results on MMLU, commonsense reasoning, world knowledge and reading comprehension, math and code for Mistral (7B/8x7B) vs Llama 2 (7B/13B/70B). Mixtral largely outperforms Llama 2 70B on all benchmarks, except on reading comprehens...Read More

When compared to Llama 2 7B and GPT-3.5, Mixtral shows significant gains in various benchmarks. For example, it achieved better scores across all tested tasks, including commonsense reasoning, math, and reading comprehension, achieving an improvement of about 5% in many instances^[1]. This makes it one of the most effective models available for general use.

Moreover, on supervised fine-tuning tasks, Mixtral 8x7B has been fine-tuned with additional instructional data, enhancing its capabilities in specific domains. A notable variant, Mixtral 8x7B - Instruct, has been specifically retrained to handle instruction-following tasks more effectively, surpassing previous generations in performance metrics^[1].

Efficiency and Computational Cost

title: 'Figure 6: LMSys Leaderboard. (Screenshot from Dec 22, 2023) Mixtral 8x7B Instruct v0.1 achieves an Arena Elo rating of 1121 outperforming Claude-2.1 (1117), all versions of GPT-3.5-Turbo (1117 best), Gemini Pro (1111), and Llama-2-70b-chat (1077). Mixtral is currently the best open-weights model by a large margin.' — title: 'Figure 6: LMSys Leaderboard. (Screenshot from Dec 22, 2023) Mixtral 8x7B Instruct v0.1 achieves an Arena Elo rating of 1121 outperforming Claude-2.1 (1117), all versions of GPT-3.5-Turbo (1117 best), Gemini Pro (1111), and Llama-2-70b-chat (...Read More

Mixtral excels not only in performance but also in operational efficiency. It demonstrates high throughput while maintaining low latency, making it suitable for deployment in real-world applications. The choice to utilize only a subset of experts for each token translates into reduced computational demands, which is particularly beneficial for large-scale deployments^[1].

Further, the model's architecture ensures that memory costs are kept in check, with much less overhead than other comparable setups. This allows for more flexible configurations and practical applications, particularly in environments where computational resources are limited^[1].

Multilingual Capabilities

One of the outstanding features of Mixtral is its ability to handle multilingual data effectively. Leveraging its expanded capacity during pretraining, it outstrips other models in maintaining high accuracy across multiple languages. This capability is increasingly critical as global applications for language models expand, requiring robust performance across diverse linguistic contexts^[1].

Conclusion

Mixtral 8x7B represents a significant leap forward in the landscape of language models, particularly in its application of the mixture-of-experts architecture. By ingeniously balancing the use of parameters while maintaining operational efficiency, Mixtral not only enhances performance but also broadens the potential applications for language processing technologies. With its advanced training methodologies and superior benchmarks, it stands out as a valuable tool for developers and researchers alike^[1].

The ongoing development of such models is expected to pave the way for even more powerful and versatile artificial intelligence capabilities in the near future. The focus on multilingual understanding and specialized instruction-following tasks makes Mixtral a compelling choice for various industries.

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