Date: Fri, 4 Oct 1996 00:08:55 +1000 From: Bruce Evans <bde@zeta.org.au> To: bde@zeta.org.au, Tor.Egge@idt.ntnu.no Cc: freebsd-hackers@freebsd.org Subject: Re: Interrupt lossage in FreeBSD-current. Message-ID: <199610031408.AAA17572@godzilla.zeta.org.au>
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>I no longer see this as a latency issue with regard to the RTC. >Something else was causing one RTC interrupt to be lost. It may have been a software bug. I just implemented lazy masking of interrupts (don't make in the ICU except in the unusual event that an interrupt repeats while it is being handled) and had problems because I forgot about the intN instructions in icu.s. The intN's were interpreted as repeated interrupts and not serviced. You could easily have a similar bug in attempting to not service the same clock interrupt twice. Statistics for lazy masking on an isa system: interrupt total repeated clk0 irq0 2052707 5107 rtc0 irq8 2610866 26 fdc0 irq6 2 0 sc0 irq1 1739 20 lpt0 irq7 1 0 wd0 irq14 6339295 2448 ed0 irq15 411078 2761 Lazy masking saved a whole 17 seconds out of 5.5 hours of uptime :-). The relatively large number of wd0 irqs is for testing something that involved too many synchronous metadata updates. Bruce
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