Due / SerialUSB losing bytes (high write rate/small buffer size)

_From @pottedplant on August 23, 2013 21:55_

dd if=foo of=/dev/ttyACM1 bs=64 # works fine
dd if=foo of=/dev/ttyACM1 bs=1 # ~13% byte loss
dd if=foo of=/dev/ttyACM1 bs=2 # ~5% byte loss
dd if=foo of=/dev/ttyACM1 bs=3 # seems to work fine

-- edit: test sketch:
void setup() {
Serial.begin(115200);
SerialUSB.begin(115200);
}

void loop() {
char buffer[512];
int l = SerialUSB.readBytes(buffer,512);
if(l) Serial.println(l);
}

-- edit: stty settings: disabled everything except: cs8 cread clocal 115200

_Copied from original issue: arduino/Arduino#1551_