BogoMIPS

Altera_Forum · ‎05-09-2005

Iam able to get a maximum of 24.67 BogoMIPS with NIOSII on Cyclone 1C20 Eval Board

running at 50 MHz (NIOS II/f - with maximum CPU features)

Is it possible to get more MIPS using NIOS II. If so, how to do that?

BTW, does the BogoMIPS gives a correct (or approx) MIPS rating for NIOS II

Altera_Forum · ‎05-11-2005

The BogoMIPS is possibly reporting incorrect values for the NIOS II core.

I uses a dhrystone benchmark and it gave me VAX MIPS 53

(I think it should a correct for a 50 MHz 32-bit Core with most

of the instructions being 32 Bit long)

Altera_Forum · ‎05-11-2005

BogoMIPS should not be confused with any real measure of processing power.<div class='quotetop'>QUOTE </div>

--- Quote Start ---

BogoMips are Linus's invention. The kernel (or was it a device driver?) needs a timing loop (the time is too short and/or needs to be too exact for a non-busy-loop method of waiting), which must be calibrated to the processor speed of the machine. Hence, the kernel measures at boot time how fast a certain kind of busy loop runs on a computer. "Bogo" comes from "bogus", i.e, something which is a fake. Hence, the BogoMips value gives some indication of the processor speed, but it is way too unscientific to be called anything but BogoMips.[/b]

--- Quote End ---

For more information on BogoMIPS, see the bogomips mini-howto (http://www.tldp.org/howto/bogomips/x78.html).

The code that generates the BogoMips value can be found in <Nios II installation directory>/bin/eclipse/plugins/com.microtronix.nios2linux.kernel_0.1.5/linux-2.6.x/init/main.c

Dennis Scott

Microtronix Datacom Ltd.

Altera_Forum · ‎05-11-2005

The number of BogoMIPS is dependent on how long the loop the architecture implements. You can only use it to compare different NIOS II cores without touching that loop (which is in kernel).