How to measure the performance hit of changes in kernel code

On Sat, Aug 20, 2011 at 07:36, john k [off-list ref] wrote:

What is the optimal way to measure the performance hit a change in the
kernel brings to the system under normal conditions?
Are there tools for this job or a standard procedure kernel developers
follow or everyone comes up with his own metrics?
I know it sounds vague and maybe the measurement must be related with where
the change is on the kernel code.
Say for example that I implemented some extra security checks in the
copy_from_user function, or some other critical code. Whats the best way to
measure the performance hit it causes?

"Daily workload" such as kernel compile is one of the test, so IMO you
already did one good test. However, since you are talking about
"micro" change, the effect might be negligible to some extent.

AFAIK, Linux Test Project (http://ltp.sourceforge.net/) is a (almost?)
standard way to do Linux benchmark (be it kernel or user space). Most
of linux benchmark is usually a composed form of integrated tools like
IoZone, volanomark, interbench and so on.

You might also need things like Linux Trace Toolkit
(http://lttng.org/) that allows you to very detailed code coverage and
code tracing, almost like gcov and gprof but with finer grained
precision.

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com