  In recent years, the application of multimodal large language models (MLLM)
in various fields has achieved remarkable success. However, as the foundation
model for many downstream tasks, current MLLMs are composed of the well-known
Transformer network, which has a less efficient quadratic computation
complexity. To improve the efficiency of such basic models, we propose Cobra, a
linear computational complexity MLLM. Specifically, Cobra integrates the
efficient Mamba language model into the visual modality. Moreover, we explore
and study various modal fusion schemes to create an effective multi-modal
Mamba. Extensive experiments demonstrate that (1) Cobra achieves extremely
competitive performance with current computationally efficient state-of-the-art
methods, e.g., LLaVA-Phi, TinyLLaVA, and MobileVLM v2, and has faster speed due
to Cobra's linear sequential modeling. (2) Interestingly, the results of
closed-set challenging prediction benchmarks show that Cobra performs well in
overcoming visual illusions and spatial relationship judgments. (3) Notably,
Cobra even achieves comparable performance to LLaVA with about 43% of the
number of parameters. We will make all codes of Cobra open-source and hope that
the proposed method can facilitate future research on complexity problems in
MLLM. Our project page is available at: https://sites.google.com/view/cobravlm.
