I have been experiencing the following behavior on my alpha with many
kernel versions (2.4 series, latest is 2.4.19 with Ingo's O(1) scheduler
patch).
I'm running apache and zope, and when I load a zope page, the load jumps
to ~12 and the computer starts skipping. That is, about once every 2s
the music (xmms) stops for ~0.5s and then comes back. This repeats
every 2s until zope is finished creating the page (which takes sometimes
longer than a minute). When the computer "skips", not only does the
music stop, but the mouse stops moving (i.e. I move it continuously and
it pauses for 0.5s every 2s). This happens both at the console in X and
on virtual terminals (ssh'ed from another computer). It's as if it's
not servicing interrupts for 0.5s. Or does scheduling not occur when
the kernel decides to load N pages from swap, no matter how large N is?
This is totally due to swap use. If I turn off all swap ('swapoff -a'),
the response of zope is speedy. This behavior has happened with all
kernel versions I have used, at least since 2.4.17.
So, any ideas? I know there have been arguments about the 'swappiness'
of this kernel, but the load going to 12 and interrupts not being
serviced is totally quantitative and totally repeatable...
Cheers,
-- Bob
Bob McElrath
Univ. of Wisconsin at Madison, Department of Physics
"The surest way to corrupt a youth is to instruct him to hold in higher
esteem those who think alike than those who think differently."
-- Nietzsche