Re: rtc: lost some interrupts at 256Hz

[Jan Engelhardt <jengelh@linux01.gwdg.de>]

On Apr 20 2006 16:57, linux-os (Dick Johnson) wrote:
>On Thu, 20 Apr 2006, Michael Monnerie wrote:
>
>> When you google for such messages, you can find a lot of people asking,
>> but nobody seems to have an answer. That's why I ask this list, where
>> the Godfathers Of Linux reside, and maybe someone hears my prayer and
>> could explain us sheep what you should do in such a case. Increase the
>> HZ from 250 to 1000, or decrease to 100? Or maybe setting the
>> preemption model from server to voluntary or preemptible? Or is that
>> whining to be ignored, and if yes, what is this message for at all?
>>
>> Please give us wisdom, and we will spread your word. Amen.
>>
>> Answers please per PM, I'm not on this list.
>
>If you are losing interrupts at 256 Hz, you have either/or:
>(1) Some very BAD driver that is disabling interrupts for way too long.
>(2) Some very slow CPU (like 40 Mhz) that is being overwhelmed by a lot of
>network interrupt activity.

On Apr 20 2006 17:03, Lee Revell wrote:
>Date: Thu, 20 Apr 2006 17:03:02 -0400
>Changing the preemption model to voluntary or full preemption could
>certainly help.  What app is using the RTC, mplayer?


I see this message too. (And I've got some more details).

Whenever I switch from console to X, I get that message. I presume it is 
due the binary nvidia blob I have loaded, because when switching to X, 
even the sound gets distorted for a microsecond (the well-known the 
soundcard replays the sound buffer - no new data transferred to it).
Yeah, looks like something's keeping IRQ disabled for quite a while.
(My normal freq is 100 Hz + no preemption, if that makes any difference.)

I have not yet seen this on the free nv driver for Xorg or the (free) 
ati/Xorg. Same configuration (100 Hz, no preempt), though!

Does not really matter what userspace app is running. If it's mplayer the 
message is "rtc: lost some interrupts at 1024Hz.", and if it's VMware it's 
whatever the Guest OS requires, mostly 2000 or 200 Hz.


Jan Engelhardt
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