Re: [gentoo-user] [O.T] Kernel and general Linux Benchmarking

[Uwe Thiem]

On 14 December 2006 15:03, Bruno Santos wrote:
> Hello all.
>
> I need to perform some benchmarks with the Kernel and with the distro
> itself but i cannot find any satisfactory app for that.

... and you probably won't. The question is: How do you benchmark a whole 
system?

If you have some some number crunching application, it is relatively easy to 
benchmark that particular app. Feed it a certain data set and measure the CPU 
time it takes to finish. Repeat several times and calculate an average for 
trashed and non-trashed memory. Do the same on different systems and compare.

Same for anything that simply runs, once started, until it has finished - like 
a compiler run on a set of sources.

A whole system, even if it is commandline-only, is a different kettle of fish. 
What do you measure? Start-up times of applications under different 
circumstances (low, medium, high system load), that's possible again. Once 
the (interactive) application - say vim - runs, it will wait for your next 
keystroke at full CPU speed anyway. It becomes even more difficult with a GUI 
since they are all driven by user events. And yet, you are still benchmarking 
applications. The question remains: What *is* the performance of a whole 
system?

As for the kernel, you can measure certain of its aspects. How fast is a fork? 
How fast are the various methods of IPC (sockets, pipes, shared memory,...)? 
How good is IO (system bus, harddisk, network,...) throughput? How fast are 
certain system calls? And so on, and so on. So you can test certain kernel 
functions. Like with a whole system, what is the performance of a kernel?

I don't have any good answer for either question, kernel and system. :-(

Uwe

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