Tricky question, what happens when CPU/load goes over dedicated limit

risharde

This is a possible tricky question all stemming from my database cluster using not super high end nodes (but they are all dedicated at the moment). However, I thought about adding a few vpses that have dedicated cpu for the sake of it. However, when I max writes (via test script, not real world scenario) on my current cluster, my load goes up as high as 60 on 4 cores. So what happens on a vps with 4 dedicated cores - assuming the load goes to 60. I'm assuming virtualization falls apart right and it becomes an abuse case? Just curious if my assumption is correct here because I am assuming the host node must deal with the load somehow? Any providers with any experience with this? Pretty sure I had a net cup vps that had load of 10 and never got complain (and yes this was certainly due to a misconfiguration on my part) but they never complained but a load of 60 makes me wonder.

yoursunny

"load" is a concept from your kernel and is invisible from outside the KVM.
Hence, you can continuing abusing CPU, as long as you don't exceed I/O limits.

risharde

@yoursunny said:
"load" is a concept from your kernel and is invisible from outside the KVM.
Hence, you can continuing abusing CPU, as long as you don't exceed I/O limits.

Thank you @yoursunny for the insight there. I thought about this but wasn't sure so happy to have you confirm that.

Neoon

If they are 100% dedicated, you don't have to worry about cpu usage at all.
However, still keep an eye on I/O, since this is still shared, especially when you run a fat database.

risharde

@Neoon said:
If they are 100% dedicated, you don't have to worry about cpu usage at all.
However, still keep an eye on I/O, since this is still shared, especially when you run a fat database.

Thanks @Neoon! If anyone knows, do VPS providers usually limit VPS I/O to avoid these type of situations? Just an added curiousity there. I should indeed double check to see if the high load is an effect of IO saturation (very likely I suspect!)

Neoon

@risharde said:

@Neoon said:
If they are 100% dedicated, you don't have to worry about cpu usage at all.
However, still keep an eye on I/O, since this is still shared, especially when you run a fat database.

Thanks @Neoon! If anyone knows, do VPS providers usually limit VPS I/O to avoid these type of situations? Just an added curiousity there. I should indeed double check to see if the high load is an effect of IO saturation (very likely I suspect!)

Some do, some don't because e.g it looks better on the benchmarks.
So you could already have a limit on your box, but still then, it could be configured to limit the impact of a potential abuse however hitting the limit consistently could be still seen as abuse by the provider.

Just ask your provider and keep monitoring your machine.

afn

@risharde said: do VPS providers usually limit VPS I/O to avoid these type of situations?

Few known hosts here do it. Netcup, Contabo, Hostslick...