Re: Linux & X11 & IRQ Interrupts

From: Justin Piszcz (
Date: Sun May 05 2002 - 20:37:26 EST

Thanks for the information.

"David D. Hagood" wrote:

> Justin Piszcz wrote:
> > With the console speaker attached, it can be clearly heard, as well as
> > performing fast packet movements (nmap (with insane option)) or such you
> > can literally hear the packets.
> What you are hearing is the noise in the computer's power supply. As the
> load on the power supply changes, the voltage changes by a few tens of
> millivolts, and that is the noise you are hearing.
> This primary reason you don't hear this under Windows and you hear it
> under Linux is that Linux will shut the processor off when there is
> nothing to do, greatly reducing the load on the power supply. When
> something happens, like a mouse interrupt or a network interrupt, the
> CPU springs back to life, drawing a burst of power from the power supply
> and momentarily bringing the voltage down a bit. This cycling of the CPU
> happens in microseconds.
> Windows, especially older versions of Windows, doesn't do this - when
> there is no work for the CPU, it spins in a busy loop looking for work.
> As a result, the load on the power supply never changes. Of course, your
> system will also run hotter and burn more power.
> If this bothers you, you could try getting another power supply (one
> that is "stiffer" and less prone to voltage sag) or you could run a
> program like Seti@home or Distributed.Net and keep your CPU busy all the
> time.

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This archive was generated by hypermail 2b29 : Tue May 07 2002 - 22:00:25 EST