Re: [2.4.17/18pre] VM and swap - it's really unusable

jogi
2002-01-13T15:24:06Z

On Sat, Jan 12, 2002 at 02:00:17PM -0500, Ed Sweetman wrote:
>
>
> > On Sat, Jan 12, 2002 at 09:52:09AM -0700, yodaiken@fsmlabs.com wrote:
> > > On Sat, Jan 12, 2002 at 04:07:14PM +0100, jogi@planetzork.ping.de wrote:
> > > > I did my usual compile testings (untar kernel archive, apply patches,
> > > > make -j<value> ...
> > >
> > > If I understand your test,
> > > you are testing different loads - you are compiling kernels that may
> differ
> > > in size and makefile organization, not to mention different layout on
> the
> > > file system and disk.
>
> Can someone tell me why we're "testing" the preempt kernel by running
> make -j on a build? What exactly is this going to show us? The only thing
> i can think of is showing us that throughput is not damaged when you want to
> run single apps by using preempt. You dont get to see the effects of the
> kernel preemption because all the damn thing is doing is preempting itself.
>
> If you want to test the preempt kernel you're going to need something that
> can find the mean latancy or "time to action" for a particular program or
> all programs being run at the time and then run multiple programs that you
> would find on various peoples' systems. That is the "feel" people talk
> about when they praise the preempt patch. make -j'ing something and not
> testing anything else but that will show you nothing important except "does
> throughput get screwed by the preempt patch." Perhaps checking the
> latencies on a common program on people's systems like mozilla or konqueror
> while doing a 'make -j N bzImage' would be a better idea.

That's the second test I am normally running. Just running xmms while
doing the kernel compile. I just wanted to check if the system slows
down because of preemption but instead it compiled the kernel even
faster :-) But so far I was not able to test the latency and furthermore
it is very difficult to "measure" skipping of xmms ...

> > Ouch, I assumed this wasn't the case indeed.

Sorry for not answering immedeatly but I am compiling the same kernel
source with the same .config and everything I could think of being the
same! I even do a 'rm -rf linux' after every run and untar the same
sources *every* time.

Regards,

Jogi

--

Well, yeah ... I suppose there's no point in getting greedy, is there?

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