Hi Michael,

On 1/20/20 8:45 AM, Michael Hinton wrote:
> Hello,
> 
> 
> I have found that running code in an inmate is a lot slower than running
> that same code in the root cell on my x86 machine. I am not sure why.
> 
> 
> Am I correct in assuming that when `jailhouse enable <root_cell>` is
> called, everything that runs after that in the Linux root cell is
> running under the hypervisor, even when the inmate hasn’t started yet?

Correct. All former hardware resources are assigned to the root cell.
This includes, e.g., all CPUs.

> Both the inmate and the Linux root cell should both be equally
> subjectedto the same hypervisor performance penalty, right?

More exits, more overall penalty. Depends on your test case. You can use
jailhouse cell stats to account for exits.

Is it a single-threaded application? Of course, your non-root cell will
have less CPUs than the root cell.

I experienced a similar performance drop a while ago. In my case, it was
misconfigured CAT -- too little cache for the non-root cell hit the
performance.

> 
> 
> Are there any high-level differences between the root and the inmate
> that could account for this large discrepancy? I know that Turbo Boost
> is likely not happening in my inmate while it is happening in the root
> cell, but I don’t believe that can account for the huge gap in execution
> duration that I see.

Could also be some power-related issue… But what gap do you see? What's
your test case?

  Ralf

> 
> 
> I'm not expecting anyone to debug this in depth for me, but I would
> appreciate any ideas I could look into.
> 
> 
> Thanks,
> 
> Michael
> 
> 
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