Re: UP 2.2.18 makes kernels 3% faster than UP 2.4.0-test12

Mike Galbraith
2000-12-12T14:47:55Z

On Tue, 12 Dec 2000, Rik van Riel wrote:

> On Mon, 11 Dec 2000, Steven Cole wrote:
>
> > Building kernels is something we do so frequently and this test
> > is so easy to reproduce is why I performed it in the first
> > place. I think it may be as good a test of real performance as
> > some of the more formal benchmarks. Comments anyone?
>
> Just one comment. You cannot use a kernel build to measure
> other things than those subsystems which the kernel build
> excercises.

One comment back ;-)

Of course.

> Things you could measure with a kernel build: scheduling (L2
> cache efficiency), fork, readahead, cpu speed, framebuffer
> speed (in the make dep phase) and maybe hard disk speed.

Yes, among others. RealHardLife hard disk speed.. kinda sorta.

> Things you cannot measure with a kernel build: networking,
> swapping (unless you do a very big parallel build, and even
> then it's questionable), raw IO speed (the kernel build is
> latency sensitive, but doesn't need much throughput), ...

I believe you are wrong wrt parallel kernel builds as swap test..
it's not questionable at all. :) Or, if it is, please explain why.

My view:

The kernel build is above and beyond all other considerations a CPU
bound job which has a cachable component which is not negligable,
and has an I/O component, but not a dominating one. That makes it
an ideal generic test candidate for vm throughput.. in any box not
blessed with unlimited I/O capability.

I think that a parallel kernel build is the perfect basic VM functional
test _because_ of it's simple requirements. Limit the I/O to what your
box can deliver (must know before testing), and it's fine.

I agree if you say that it's nothing beyond a basic functionality test.

I test this way because my box doesn't have the hardware to do serious
I/O.. and neither do at least 99.9% of other boxen out there.

What else can you suggest to test basic VM throughput in an I/O starved
environment? It has to be multi-task, and has to be CPU bound to be
meaningful.

-Mike