Hi3516CV610-20S运行yolov8，MMZ内存不够

易百纳海思Hi3516V610开发版AI视觉低功耗摄像机IPC安防模组
Hi3516CV610-20S主板+4mm镜头

./sample_svp_npu_main a 8 1 6
这个模式能运行

./sample_svp_npu_main a 8 1 4
这个模式不能运行，系统显示MMZ内存不足
[Func]:ot_mpi_sys_mmz_alloc_only [Line]:369 [Info]:system alloc mmz memory failed!
[Func]:svp_npu_mem_malloc [Line]:75 [Info]:Error, malloc mmz mem(size: 17726208) failed
[level]:Error,[func]:sample_svp_npu_malloc_mem [line]:473 [info]:can’t malloc buffer, size is 17726208, error code is 200000!
[level]:Error,[func]:sample_common_svp_npu_create_input_data_buffer [line]:510 [info]:3-th input malloc mem failed!
[level]:Error,[func]:sample_common_svp_npu_create_work_buf [line]:773 [info]:create work buf failed!
[level]:Error,[func]:sample_svp_npu_acl_init_task [line]:347 [info]:create work buf failed.
[level]:Error,[func]:sample_svp_npu_acl_e2e_yolo [line]:959 [info]:init task failed!
我尝试过用用fw_setenv os_mem_size 32M
修改内存分配，但是开机时候，系统无法运行起来。请问，如何运行