Date: Wed, 01 Nov 2006 10:49:36 -0500 From: Lowell Gilbert <freebsd-questions-local@be-well.ilk.org> To: mexas@bristol.ac.uk, freebsd-questions@freebsd.org, Reply-To@be-well.ilk.org, freebsd-questions@freebsd.org Subject: Re: lpt0 printer slows system response significantly Message-ID: <44slh3goa7.fsf@be-well.ilk.org> In-Reply-To: <45485490.D5trgMIQ1JYsEyMX%perryh@pluto.rain.com> References: <20061101000426.GA60303@mech-aslap33.men.bris.ac.uk>, <45485490.D5trgMIQ1JYsEyMX%perryh@pluto.rain.com>
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perryh@pluto.rain.com writes: >> PID USERNAME THR PRI NICE SIZE RES STATE TIME WCPU COMMAND >> 18 root 1 -60 -179 0K 8K *Giant 15:09 77.05% irq7: lpt0 >> 11 root 1 171 52 0K 8K RUN 48.0H 11.13% idle > > The interrupt service for the parallel port is using over 3/4 of > the CPU, and half of the rest is "idle". > > I take it this is a laser printer, which can consume bytes from the > parallel port as fast as the processor can send them. Top-of-head > dump of ways to cut down on the interrupt traffic: > > * Get a DMA-capable parallel port (supposing such exist, and FreeBSD > supports them); > > * Move the printer to a network connection or dedicated print server; > > * Somehow tell the printer not to receive so quickly. * Change the printer port to polled mode. ["lptcontrol -p"] With this kind of hardware, it may even speed up your printing as well.
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