Date: Wed, 1 Nov 2006 22:36:30 -0800 From: "Ted Mittelstaedt" <tedm@toybox.placo.com> To: <perryh@pluto.rain.com>, <mexas@bristol.ac.uk> Cc: freebsd-questions@freebsd.org Subject: Re: lpt0 printer slows system response significantly Message-ID: <036401c6fe49$3ba45150$3c01a8c0@coolf89ea26645> References: <20061101000426.GA60303@mech-aslap33.men.bris.ac.uk> <45485490.D5trgMIQ1JYsEyMX%perryh@pluto.rain.com>
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You can also get a faster CPU, more cycles available for servicing interrupts. Ted ----- Original Message ----- From: <perryh@pluto.rain.com> To: <mexas@bristol.ac.uk> Cc: <freebsd-questions@freebsd.org> Sent: Wednesday, November 01, 2006 12:02 AM Subject: Re: lpt0 printer slows system response significantly > > 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. > > Alternatively, one possible way to handle that sort of interrupt > load without bogging down is to get a second CPU and run SMP, so > you've still got a CPU available for tasks when one is swamped > with interrupt traffic. > > The other thing that *might* help some is more RAM, if it happens > that the idle time is caused by page wait due to the set of active > threads needing more RAM than you have, but this will at best get > your tasks up from 1/9 of the CPU to 2/9. > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.org" >
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