[Devel] kernel thread accounted to a VE

[Denis V. Lunev]

Eric Keller wrote:
> Is it possible to start a kernel thread and then move it to a particular
> VE?
> I have the following code inside of a kernel thread:
> envid_t _veid = 200;
> // enter that VE
> unsigned flags = VE_ENTER;
> int err = real_env_create(_veid, flags, 0, 0, 0); // the last 3
> arguments are only used if flags is VE_CREATE
> 
> I needed to modify ve_move_task() a bit.  It has the following
> assignment:  tsk->mm->vps_dumpable = 0;    But for kernel_threads,
> tsk->mm is NULL, so I just check if it's null and don't do the
> assignment if it is null.  Other than that, it appears to be
> successful.  It returns successful and in the VE I moved the task to, I
> can see a new process running (using top).
> 
> The problem is, I set a cpu limit for that VE to 10%, yet I can see this
> thread go well above that amount (~50%).  User processes do get limited
> when I run them, so I know it's not a setting issue (unless there's
> something special I need to do for kernel threads).  Note that I do not
> want to allow the VEs to install kernel modules, so I want the host
> system to do it on their behalf for a very specific circumstance.
> 
> Any ideas of what I'm doing wrong or what it'll take to make this work?

first of all, you should check that enter was successful :) The most
simple case is that is don't. This can be confirmed by the ret code
checking and via /proc/<pid>/status of the particular thread

Regards,
	Den