Load averages in guest

Hi, I'm fairly certain this is a silly question, but I will ask it anyway: I'm wondering if anyone knows if CPU load averages from within a Linode guest are affected by other users on the host, or is it only related to your own usage. I've been seeing a strange issue for the past few hours where a server which usually averages about 0.02 to 0.04 per core is suddenly showing 5 and 15 minute load averages >0.4, with 1 minute averages often exceeding 1.0. I've sat watching htop for about an hour now, and none of the individual cores on my system ever peak above 2%, yet the load averages are showing as above, almost constantly. If I sort by CPU usage, arpon is permanently pinned to the top of the list with between 1.3% and 2% usage per core – nothing ever jumps higher, yet the 1 min load spikes periodically. I'm currently trying to figure out if something has gone horribly wrong that I'm just not seeding, or if it's possible the load is being affected by another Linode, or something similar.

Edit: actually, now that I look at plain old top, this seems to be being caused by high wait times (there's also a little bit of steal, but it's minimal and occasional, the wait %s are high and frequent). However, looking at iotop -- there' nothing out of the ordinary / no very large or long-running writes or reads from individual processes (all in the 0.00 to 0.0X, or sometimes low 0.XX percentages of i/o). [jbd2/dm] is accumulating quite a lot of I/O%, but is not actually writing that much out data – comparing this to the same server image running on another Linode, the amount of data being written out is similar, but the I/O% used is quite different. I'm completely confused now!

1 Reply

Hello,

I'm wondering if anyone knows if CPU load averages from within a Linode guest are affected by other users on the host, or is it only related to your own usage.

When it comes to load averages, in theory they would not be directly affected by other users on the host, since your load average is a measurement having to do with your processes and how they utilize your available CPU.

With that said, in a virtual environment, it can be expected to see minor amounts of CPU steal, but this should not significantly affect your load averages.

If you continue to see issues with this, I'd suggest opening a ticket with us through your Linode Manager, and providing all the pertinent details so we could investigate further to make sure there aren't issues with the host your Linode is on. In the event this has something to do with the internal configuration of your Linode, we'd be happy to help troubleshoot with you and help point you in the right direction.

Cheers,
Joe C.

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