Re: [PATCH 0/4] Virtual Machine Time Accounting

Peter Zijlstra
2009-08-04T14:17:29Z

These patches never seem to have made it onto LKML?!

On Mon, 2007-08-20 at 15:13 +0200, Laurent Vivier wrote:
> The aim of these four patches is to introduce Virtual Machine time accounting.
>
> _Ingo_, as these patches modify files of the scheduler, could you have a look to
> them, please ?
>
> [PATCH 1/4] as recent CPUs introduce a third running state, after "user" and
> "system", we need a new field, "guest", in cpustat to store the time used by
> the CPU to run virtual CPU. Modify /proc/stat to display this new field.
>
> [PATCH 2/4] like for cpustat, introduce the "gtime" (guest time of the task) and
> "cgtime" (guest time of the task children) fields for the
> tasks. Modify signal_struct and task_struct. Modify /proc/<pid>/stat to display
> these new fields.
>
> [PATCH 3/4] modify account_system_time() to add cputime to cpustat->guest if we
> are running a VCPU. We add this cputime to cpustat->user instead of
> cpustat->system because this part of KVM code is in fact user code although it
> is executed in the kernel. We duplicate VCPU time between guest and user to
> allow an unmodified "top(1)" to display correct value. A modified "top(1)" is
> able to display good cpu user time and cpu guest time by subtracting cpu guest
> time from cpu user time. Update "gtime" and "cgtime" in signal_struct and
> task_struct accordingly.
>
> [PATCH 4/4] Modify KVM to update guest time accounting.

Isn't this exactly what CONFIG_VIRT_CPU_ACCOUNTING is about?