kern/78711: Parallel printer incredibly slow

[Jason Bacon]

The following reply was made to PR kern/78711; it has been noted by GNATS.

From: Jason Bacon <bacon at smithers.neuro.mcw.edu>
To: Bruce Evans <bde at zeta.org.au>
Cc: freebsd-bugs at freebsd.org
Subject: Re: kern/78711: Parallel printer incredibly slow
Date: Mon, 14 Mar 2005 17:55:19 -0600 (CST)

 Mark another one resolved...
 
 sysctl hw.intr_storm_threshold=2500 seems to have done the trick.
 
 I printed a high quality photo from my iBook, and the job ran just fine. 
 Top showed the CPU usage split between system and interrupt, whereas it 
 was all system in polling mode as one might expect.
 
 I went back and checked my /var/log/messages from before the change, and 
 noticed:
 
 Interrupt storm detected on "irq7: lpt0"; throttling interrupt source
 stray irq7
 
 I also repeated the experiment for confidence:
 
 sysctl hw.intr_storm_threshold=500
 re-ran same print job and watched it stall
 sysctl hw.intr_storm_threshold=2500
 re-ran same print job and watched it complete
 
 If you're interested in collecting some data on the topic, I can play with 
 the threshold values and look for a working minimum for my needs.
 
 Let me know,
 
  	Jason
 
 
 On Sat, 12 Mar 2005, Bruce Evans wrote:
 
 > On Fri, 11 Mar 2005, Suporte Matik wrote:
 >
 >> On Friday 11 March 2005 19:42, Jason Bacon wrote:
 >>>> Description:
 >>> 
 >>> 	The parallel printer runs ridiculously slow.  It prints normally
 >>> 	for about 30 seconds, then prints one line every 5 or 10 minutes.
 >>> ...
 >> 
 >> any two lines text file needs 15 minutes to be printed
 >> 
 >>>> Fix:
 >>> 
 >>> 	lptcontrol -s resolves the problem.  This looks to me much
 >>> ...
 >> 
 >> does not fix, the problem is as well with lpr and cups local/remote
 >> 
 >> the only way to get "some more speed" is using b/w and 150 dpi on a HPDJ, 
 >> any
 >> gray or color mode is slow
 >
 > Try changing the interrupt storm threshold (hw.intr_storm_threshold) to
 > something larger than the printer can generate.  FreeBSD-5.3 has interrupt
 > storm detection that misdetects the very high interrupt rates that can
 > be caused by printers (combined with low quality interrupt handling in
 > the lpt driver) as interrupt storms.
 >
 >> doesn't matter what you set in the BIOS or whatever, any gray or colormode 
 >> on
 >> 5.3 is that inacceptable slow
 >> 
 >> using the exactly same printer and port settings on 5.2.1 or 4.11 brings 
 >> you
 >> back to the expected printing speed
 >
 > FreeBSD-5.2 and FreeBSD-current have different bugs in interrupt storm
 > detection and handling.  In at least some versions, the bugs make printers
 > go even slower if an interrupt storm is misdetected for them, but
 > misdetection is apparently rarer.
 >
 > FreeBSD-4 doesn't have interrupt storm detection, so any problems with
 > printer speed are local to the driver.
 >
 > Bruce
 >
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