lpt0 printer slows system response significantly

[Anton Shterenlikht]

On Wed, Nov 01, 2006 at 10:49:36AM -0500, Lowell Gilbert wrote:
>  * Change the printer port to polled mode.  ["lptcontrol -p"]
>    With this kind of hardware, it may even speed up your printing as well.

	Thanks a lot, I think it does print a bit faster. But more
importantly I see virtually no performance degradation during
printing.

	Perhaps a sentence on this should be added in section
9.3.1.3 (Setting the Communication Mode for the Parallel Port) of
the user manual somewhere in the end of this pararaph:

	The interrupt-driven method is usually somewhat
	faster but uses up a precious IRQ line. Some newer
	HP printers are claimed not to work correctly in
	interrupt mode, apparently due to some (not yet
	exactly understood) timing problem. These printers
	need polled mode. You should use whichever one works.
	Some printers will work in both modes, but are
	painfully slow in interrupt mode.

and then add something like:

	On slower machines using interrupt mode might cause
	significant degradation of the overall system perfor-
	mance due to the interrupt service using most of the
	CPU time. On such machines changing to polled mode
	will balance the CPU load as well as result in
	faster printing.

	Perhaps I should send a message to the documentation
list?

anton