Re: [PATCH] local_irq_disable removal

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Gene Heskett wrote:
[...]
Lets add the operation of 4 or more stepper motors in real time for smaller milling machines. There, the constraints are more related to maintaining a steady flow of step/direction data at high enough speeds to make a stepper, with 8 microsteps per step, and 240 steps per revolution, run smoothly at speeds up to say 20 kilohertz, or 50 microseconds per step, maintaining that 50 microseconds plus or minus not more than 5 microseconds else the motors will start sounding ragged and stuttering.

This is the kind of problem that is screaming "give me dedicated hardware!". Why would one spend $500+ on a PC to do the work of a $2 microcontroller (and possibly throw in an FPGA to the mix)?. Not to mention that the microcontroller/FPGA would maintain 50us +/- 0us instead of the 50 +/- 5 you've mentioned.

The same goes for the "hand under the saw". A simple transistor/triac/whatever and a logic circuit would stop the saw, we don't need any real time OS for that (and I would certainly trust the logic circuit more than any real time OS :).

IMHO, the kind of problems where real time OS's are useful are the kind that require computational power while having real-time constraints. Like the sound effects processor for the guitar that Lee Revell already mentioned or controlling an airplane in flight that has to measure a lot of sensors, do some state space calculations with some not-so-small matrices (together with Kalman filtering, etc.) and move the actuators.

--
Paulo Marques - www.grupopie.com

An expert is a person who has made all the mistakes that can be
made in a very narrow field.
Niels Bohr (1885 - 1962)
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux