Date: Fri, 3 Nov 2006 03:03:21 +1100 (EST) From: Ian Smith <smithi@nimnet.asn.au> To: Anton Shterenlikht <mexas@bristol.ac.uk> Cc: Lowell Gilbert <freebsd-questions-local@be-well.ilk.org>, freebsd-questions@freebsd.org Subject: Re: lpt0 printer slows system response significantly Message-ID: <Pine.BSF.3.96.1061103022218.9161C-100000@gaia.nimnet.asn.au> In-Reply-To: <20061101221408.9D04216A523@hub.freebsd.org>
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On Wed, 1 Nov 2006 Anton Shterenlikht wrote: > 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 I'm not sure if that's generally true for slower machines; you haven't said (or I missed) what sort of printer you're using, what filters you run via printcap, and such? Not one covered by the existing para? I have a 1500c, bit faster than your 1700 @300MHz, that has printed lots of large files via gs without ever seeing any significant irq 7 load nor any slowdown of the machine at all - albeit using a slow old printer. Not that I see any problem with your proposed addition. Perhaps 'On some slower machines running fast printers using interrupt mode ..' ? Cheers, Ian
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