It's possible that the performance issue you are experiencing with GRE over IPSEC encryption is related to the FortiGate's hardware resources, specifically the CPU.
You mentioned that the FortiGate is a VM with 16 vCPUs, but it's possible that the hypervisor is not allocating the necessary CPU resources to the FortiGate VM. You may want to check the hypervisor's CPU allocation settings to ensure that the FortiGate VM has access to the required number of CPUs to handle the traffic.
Another potential issue could be related to the encryption algorithm and key size being used. If the FortiGate is using a high-strength encryption algorithm with a large key size, this could cause a significant increase in CPU usage and impact performance. You may want to try adjusting the encryption settings to use a weaker algorithm or smaller key size to see if this improves performance.
Additionally, you may want to check the FortiGate's IPSec settings to ensure that they are optimized for performance. For example, you can try enabling "IPSec offloading" to allow the FortiGate to offload some of the encryption processing to the network interface card (NIC).
Lastly, it may be helpful to contact Fortinet support to see if they can provide additional guidance or suggest any specific configuration changes that could improve performance for your specific use case.
he NPU (Neural Processing Unit) is a hardware component that is typically found on physical devices, such as Huawei's Ascend series of processors. It is designed to accelerate the performance of machine learning and artificial intelligence applications.
If you are using a virtual machine, it is unlikely that you have access to a physical NPU, which could be why you are seeing the "npu_flag=00" message. However, there may be other ways to optimize the performance of machine learning applications on a virtual machine, such as using GPU acceleration.
If you need further assistance with this issue, I recommend looking into the documentation or support resources for the specific software or platform you are using.
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