Server gets a high load, but no CPU use, and then later stops respond on the network

Ståle Kristoffersen staale at kristoffersen.ws
Wed Sep 21 10:19:27 UTC 2016


On 2016-09-21 at 09:35, Michael Schuster wrote:
> Hi,
> 
> While I'm not very familiar with FreeBSD internals, I'd like to point out
> two things that I think may be relevant:
> 
> 1) note that '[idle]' seems to be the only thread/process doing significant
> work - at a guess, I'd say that's the kernel doing work that cannot be
> ascribed to anything else ... housekeeping? (someone who knows FreeBSD
> better will have to answer that)

Hi, I would think those other houskeeping tasks would show up as other
kernel threads, but I might be wrong.

<snip>

> 2) look at 'sr' (using a fixed-width font probably helps). In Solaris
> (which is where I come from ... a long time ago ;-)) this is "scan rate",
> ie the number of pages (per second) the paging mechanism is looking at -
> (again on Solaris) this would mean that your system is under some kind of
> fairly constant memory pressure - where from I cannot even guess, and given
> the "avm" and "fre" columns, this does look very strange ... but that's
> what I'd continue my investigation with.

That also had my attention, but the number is much lower than it is when
the system is working fine, so I didn't look any harder at it.
Can anyone else chime in on what is normal?

-- 
Ståle Kristoffersen


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