In code default buffer size is 512MB
//common.h:const unsigned long long defaultBufferSize = 512; // 512 MiB
But if you give less size error thrown is of 64MB
nvbandwidth.cpp: output->recordWarning("NOTE: You have chosen a buffer size that is smaller than the default buffer size. It is suggested to use the default buffer size (64MB) to achieve maximal peak bandwidth.");nvbandwidth.cpp: output->recordWarning("NOTE: You have chosen a buffer size that is smaller than the default buffer size. It is suggested to use the default buffer size (64MB) to achieve maximal peak bandwidth.");