Re: 2.6.8-rc3-mm2

Russell King
2004-08-10T13:17:46Z

On Tue, Aug 10, 2004 at 03:01:22PM +0200, Ingo Molnar wrote:
>
> * William Lee Irwin III <wli@holomorphy.com> wrote:
>
> > On Tue, Aug 10, 2004 at 02:55:29PM +0200, Ingo Molnar wrote:
> > > i'd guess it's the con->write() in __call_console_drivers() that makes
> > > the difference. (i.e. touching the framebuffer)
> >
> > This is serial port IO; would that make the same kind of difference?
>
> serial port IO is even more heavy, it also generates IRQ traffic.

Except serial console IO does not generate _any_ IRQ traffic - it
purposely disables IRQs on the device before starting any IO to
prevent any user-level IO interfering with the console output.

It does, however, create a fair amount of IO reads and writes to
the serial port.

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core