Re: runaway intr problems: powerd and/or hw.acpi.cpu.cx_lowest related

On 08/23/2010 05:39, John Baldwin wrote:
> On Sunday, August 22, 2010 11:17:44 pm Doug Barton wrote:
>> Thanks to help from Andriy I've been working on narrowing down the cause
>> of my "runaway intr" problems and we've found some interesting things.
>> First, if I use neither powerd nor set hw.acpi.cpu.cx_lowest less than
>> C1 things seem to work fine. Using one or the other sort of works, but
>> between the 2 powerd seems to cause the most problems.
>
> I think this just means that when C3 is enabled the system is getting skewed
> results in cp_time[] and so the stats are off.  The system isn't actually
> stuck in an interrupt storm of sorts, the numbers reported to top are just
> wrong so it looks like it is.

That may be true, however what's happening at that time is that the 
video and audio both become choppy (as in, painfully so) and every other 
thing that's running, whether it's desktop clients like thunderbird or 
something being compiled, also moves very very slow, as if it's 
resource-starved. So while I'm perfectly ready to admit that the top 
output may be just a symptom instead of the real problem, something 
fundamentally bad IS happening under the hood.


Doug

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