[sdiy] Small MCU MIPS, DMIPS?

[karl dalen]

>Scott Gravenhorst <music.maker at gte.net>
> I disagree with the premise that it's useless, meaningless
> or just marketing blather.
> 
> Why don't YOU tell us exactly how we should measure it?

Dear Scott, that was not the point of this post,ofcourse
we want as many MIPS "whatever" we can get, one point i now
remember is that it's quite easy go into micro optimizing
code by ASM in the belief that we actually gain something.

I have found after several experiments whatever code i
optimize are later destroyed and improved by the optimizer!

That's great for crap software writer as me but yet i have
a hard time to believe that a supreme software writer will
outperform todays optimizers. They might but to what cost?
 
> The actual application is most important since it may or
> may not be able to use the special features provided.
> Application X on device A may run faster than on device
> B, and application Y might run faster on device B
> than on A.  So which device is faster?  That
> question is of little value. 

That question are of important matter, as suggested the
fact the dsPIC has dual ported RAM for DMA transfer as
STM32 uses arbitration but i may have missed the exact
implementation of STM32 DMA.

> So do your research, read the datasheets of the devices you
> are considering and understand how the features will affect
> the application you want to implement.  That will tell you
> more than MIPS - for  YOUR application.

Yes thats alright for restricted application but when you want
to do those extra things it might very well show up that a
switch to another device on the premises of more MIPS in
the end be no more MIPS, in fact less because of those
extra things that needs to be implemented.

Besides we can all read data sheets until our eyes bleed
yet not being able to gain those extra Mips due to a vast
number of circumstances. it's one thing for DIY and completely
different for big companies that uses millions of devices but
i really wonder if they spend the time and money doing those
MIPS comparisons when a STM32 cost like 2euro in single units.
 
> However, generally, MIPS is a basic starting point for a
> very general comparison of the devices you would consider.

Better then nothing perhaps.

> I don't believe that any engineer would consider MIPS rating
> the ultimate answer, when they need a device, they will 
> get/buy samples and benchmark themselves. But MIPS will
> help them choose a few from the many.

yes, but where do YOU draw the selection line and on which premises?
I bet it could be a cumbersome decision. 

MIPS as i recall, where based on a VAX computer measurement
not very applicable onto todays MCU's? No/Yes?

Anyhow in 10 years time MIPS are no more parameter to select from 
since then we will be using carbon based MCUs at +1Thz.Transistors
are already made at these speeds in labs.

Reg
KD (reserves for being all wrong in my assumptions)