you can use tools like "Antutu" or you can debug vpu source code to get the memory allocation, refer to the vpu_alloc_dam_buffer function in the mxc_vpu.c, if you need to know how much cma, you can refer to the imx6q.dtsi:
reserved-memory { #address-cells = <1>; #size-cells = <1>; ranges; /* global autoconfigured region for contiguous allocations */ linux,cma { compatible = "shared-dma-pool"; reusable; size = <0x14000000>; linux,cma-default; }; };