This option allows the softmax function to be implemented in hardware. It is
a separate accelerator which has its own interface and runtime with int8 input and
floating-point output data format. This softmax HW option is just packaged into DPU
wrapper. The hardware implementation of softmax can be 160 times faster than a
software implementation on MPSoC ARM in some application cases. Enabling this option
depends on the customer chose algorithm model and desired throughput.
The maximum categories number of hardware softmax is 1023.
If the categories number is greater than 1023, it is recommend to use the
software softmax. For more information, refer to the
Vitis AI Library User Guide (UG1354)
When softmax is enabled, an AXI master interface named SFM_M_AXI and an
interrupt port named
sfm_interrupt will appear in
the DPUCZDX8G IP. The softmax module uses
m_axi_dpu_aclk as the AXI clock for SFM_M_AXI
as well as for computation.
The extra resources with Softmax enabled are listed in the following
Table 1. Extra Resources with Softmax