lkml.org 
[lkml]   [2012]   [Aug]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH RFC 0/3] Add guest cpu_entitlement reporting
On 08/24/2012 11:11 AM, Michael Wolf wrote:
> On Fri, 2012-08-24 at 08:53 +0400, Glauber Costa wrote:
>> On 08/24/2012 03:14 AM, Michael Wolf wrote:
>>> This is an RFC regarding the reporting of stealtime. In the case of
>>> where you have a system that is running with partial processors such as
>>> KVM the user may see steal time being reported in accounting tools such
>>> as top or vmstat. This can cause confusion for the end user. To
>>> ease the confusion this patch set adds a sysctl interface to set the
>>> cpu entitlement. This is the percentage of cpu that the guest system is
>>> expected to receive. As long as the steal time is within its expected
>>> range it will show up as 0 in /proc/stat. The user will then see in the
>>> accounting tools that they are getting a full utilization of the cpu
>>> resources assigned to them.
>>>
>>
>> And how is such a knob not confusing?
>>
>> Steal time is pretty well defined in meaning and is shown in top for
>> ages. I really don't see the point for this.
>
> Currently you can see the steal time but you have no way of knowing if
> the cpu utilization you are seeing on the guest is the expected amount.
> I decided on making it a knob because a guest could be migrated to
> another system and it's entitlement could change because of hardware or
> load differences. It could simply be a /proc file and report the
> current entitlement if needed. As things are currently implemented I
> don't see how someone knows if the guest is running as expected or
> whether there is a problem.
>

Turning off steal time display won't get even close to displaying the
information you want. What you probably want is a guest-visible way to
say how many miliseconds you are expected to run each second. Right?


\
 
 \ /
  Last update: 2012-08-26 02:21    [W:0.200 / U:0.444 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site