[CentOS] measuring kernel speed

[Ross Walker]

On May 10, 2010, at 8:40 AM, Les Mikesell <lesmikesell at gmail.com> wrote:

> JohnS wrote:
>> On Sun, 2010-05-09 at 21:46 -0400, Ross Walker wrote:
>>> On Sat, May 8, 2010 at 7:38 PM, JohnS <jses27 at gmail.com> wrote:
>>>> On Sat, 2010-05-08 at 16:17 -0400, Ross Walker wrote:
>>>>> On May 8, 2010, at 8:35 AM, Mag Gam <magawake at gmail.com> wrote:
>>>>>
>>>>>> At our Physics research labs we do a lot with low latency  
>>>>>> networks. We
>>>>>> have been using Centos for over 3 years now and its been great!  
>>>>>> We
>>>>>> would like to tune and optimize our setup by removing unneeded
>>>>>> packages -- kernel modules to be specific. I was wondering, how  
>>>>>> does
>>>>>> one measure the speed of the kernel. Is that even possible?
>>>>> Use oprofile.
>>>>>
>>>>> -Ross
>>>> ---
>>>> Ross, never mind I just yummed it onto a machine there faq is  
>>>> inheritly
>>>> wrong.
>>> The FAQ is only correct in respect to the project's view.
>>>
>>> Redhat has a custom oprofile that works with their custom kernels,  
>>> so
>>> stock oprofile from the project's site IS incompatible, but that's  
>>> OK
>>> cause RH provides one that works with their distro.
>>>
>>> -Ross
>> ---
>> Correct as i found out.
>
> Would this also be suitable for testing efficiency loss from running  
> under
> VMware or other virtualization methods?

No because oprofile and latencytop's point of reference is just the  
running kernel and doesn't factor in CPU allocations, network/disk  
virualization/para-virtualization, bandwidth allocations, etc.

Efficiency loss is a slippery slope and VERY configuration dependant.

I have seen VMs perform better than physical machines and I have seen  
them perform worse, sometimes on the same physical host!

Go with the "user experience" indicator (assuming it is properly  
configured for the workload). Does it seem fast? Then it's fast. Does  
it seem slow? Then it is slow.

-Ross