Re: Why is the serial port so slow in Linux?

AZ Nomad wrote:
On Mon, 05 Feb 2007 17:18:17 -0900, Floyd L. Davidson <floyd@xxxxxxxxxx> wrote:


Richard <rkm@xxxxxxxxxx> wrote:
Floyd L. Davidson wrote:
What kernel are you running this on, and what is the HZ value
set to? If you have HZ set at the traditional 60, and each
read and write causes your process to give up its time slice,
this is going to be very very slow...
The kernel is 2.6.16.27. I am not familiar with the HZ
value, can you tell me what it is and how I can check it?

With a 2.6 kernel it is probably 1000. That means your
scheduler uses intervals of 1/1000 when dividing up the cpu's
The default is 250hz. 1000hz is a waste of time on a desktop system and
shouldn't be used unless there's a good reason (like fast processing
on the serial port by a user mode process)

Yup. Thats why serial ports are handled by PIO controllers and kernel level devices under interrupts.
.