Dumb question about threads in containers

[Davidoff]

I've set up a few containers on my single-node Proxmox install, each intended to run a specific application. On a couple of them, I had initially provisioned 1 core, but noticed that usage would spike to 100%. As a result, I added some additional cores to those containers. However, I noticed that the containers in question would appear to only still use a single core. For example, in one container, I increased it from 1 to 2 cores. Usage would occasionally spike to 50% but never more than that. In another, I increased it from 1 to 4, and usage would spike to 25% but not more than that.

The question I have is whether there might be something I need to do or a setting I need to change either in Proxmox or the container itself to enable usage of the additional cores allocated. Or is this more a function of the application in question, such that if it's not written to take advantage of multiple cores, then there's nothing that can be done. If relevant, I believe both applications in the containers in question are python based.

Any suggestions or thoughts would be most appreciated.

 

[dcsapak]

Or is this more a function of the application in question, such that if it's not written to take advantage of multiple cores, then there's nothing that can be done.

yes, if the application is single threaded, you cannot do anything so that it runs on multiple cores/thread simultaniously

 

[Vasu Sreekumar]

In some case you can try different CPU types, that may solve the issue. Try to select the closest CPU as the node actually has.

I have Westmere CPU, and I selected Westmere for KVM and AMD64 for LXC, and it has better performance.

 

[Davidoff]

yes, if the application is single threaded, you cannot do anything so that it runs on multiple cores/thread simultaniously

Thanks. Dammit. But thanks.

 

[Davidoff]

In some case you can try different CPU types, that may solve the issue. Try to select the closest CPU as the node actually has.

I have Westmere CPU, and I selected Westmere for KVM and AMD64 for LXC, and it has better performance.

Appreciate the suggestion. I think that option is only available for VMs. I don't see it as an option for containers.

 

[Davidoff]

yes, if the application is single threaded, you cannot do anything so that it runs on multiple cores/thread simultaniously

Just one follow-up question: Would increasing the value of CPU units for the containers in question help in this situation? Given that this value only controls relative proportionate scheduling across all containers, and the underlying host still has plenty of excess capacity, I imagine it would not, but thought it would not hurt to double check.