Best tests to measure Kernel Performance

[gregkh@linuxfoundation.org (Greg KH)]

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@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.

> I think that LTSI should have kind of a test suite with significant
> test that could help the developer to detect those perf changes. Is
> very common that one as OS developer make a change in one package (
> important one as the kernel ) and do not check how this affect the
> performance of the OS ( I know is too general , but we might show
> BKM's)

WHat is "BKM"?

> I think this might be a good topic to discuss with the community and
> we could came with a solid recommended test suite in the LTSI project.

LTSI already has a "test suite" that is uses to test the releases,
what's wrong with that?  I'm sure the developers would be glad to add
any additional tests that you want added to it that you find missing and
useful.

Also note that the upstream kernel is tested by a huge test suite of
performance tests and static analysis tools for every commit in all
development branches by the wonderful 0-day bot system.  That's been
helping prevent regressions for a long time now.

thanks,

greg k-h