Best tests to measure Kernel Performance

[Victor Rodriguez]

On Thu, Dec 3, 2015 at 2:10 AM, Nicholas Mc Guire <der.herr at hofr.at> wrote:
> On Wed, Dec 02, 2015 at 04:36:50PM -0800, Greg KH wrote:
>> On Wed, Dec 02, 2015 at 05:50:30PM -0600, Victor Rodriguez wrote:
>> > On Tue, Dec 1, 2015 at 7:32 PM, Greg KH <gregkh at linuxfoundation.org> wrote:
>> > > On Tue, Dec 01, 2015 at 06:45:51PM -0600, Victor Rodriguez wrote:
>> > >> Hi
>> > >>
>> > >> Despite the fact that this is not a well formulated question. I wonder
>> > >> what tests could be a good subset to measure the performance of the
>> > >> kernel . I have some approaches like phoronix does here :
>> > >>
>> > >> http://www.phoronix.com/scan.php?page=article&item=linux-41-byt&num=1
>> > >>
>> > >> I am sure postmark/ John the ripper/ Apache are good candidates but I
>> > >> want to ask the community if there is some specific test that you
>> > >> recommend
>> > >
>> > > It depends on what you want to test, specifically.  The "kernel" isn't a
>> > > very specific thing, what most of those tests test is the speed of the
>> > > hardware, not specifically the kernel itself.
>> > >
>> > > good luck,
>> > >
>> > > greg k-h
>> >
>> > Thanks for the feedback . You are right they test the speed of the HW
>> > however I have seen that when there is a change in the kernel for
>> > network the performance of apache is changed, which make total sense .
>>
>> Maybe, maybe not, depending on if "apache" is cpu or hardware bound
>> (networking hardware has physical limits...) again, you have to be very
>> sure about exactly what you are wanting to test before using such a test
>> to try to "validate" anything other than just raw hardware speed.
>>
>> Take a look at the "old" lmbench set of benchmarks for valid things that
>> a kernel change can affect, it's much different from what you might be
>> thinking of as a test.
>>
> We also still use lmbench as the usual first level of assessment as
> it gives a lot of information about the change set impact on low-level
> functions (system-calls, IPC, allocation...) was. It is much more precise
> than trying to detect changes in complex applications that might only be making
> a handful of a affected system call and thus look like
> performance did not change while it actually did - just its in some
> hard to reach corner case.
>
> As with all testing - you need layers of testing to get a usable
> picture of what is going on and lmbench is a good candidate for the
> lowest level. Deducing system level changes from looking at complex
> application performance changes is alost impossible.
>
> Specifically lmbench has a simple  make results; make rerun  which can give
> a good overview of differences - but actually the tests default runs are
> only a small part of what the tests can uncover so looking at individual
> microbenchmarks to discover latency/bandwidth changes can be very helpful
> also to uncover odd hardware behavior.
>
> Some other low-level benchmarks we use are:
>  rt-tests - scheduling, pi
>  NetPIPE - network bandwidth
>  bonnie++ - filesystem


Thanks a lot hofrat

I really appreciate all the help I think that is time to turn my eyes
to lmbench for sure as well to the tools you mention :)

Yes a lot of layers are necessary to measure the QA of an OS , we need
full image test as well as cloud tests ( since our OS is designed for
Cloud ) . lmbench will be amazing for low level

I really appreciate all the help


> thx!
> hofrat
>