Subject: Re: UVM/other problems for desktop users in current?
To: George Michaelson <>
From: Greg A. Woods <>
List: current-users
Date: 12/17/2002 22:49:35
[ On Wednesday, December 18, 2002 at 12:58:00 (+1000), George Michaelson wrote: ]
> Subject: UVM/other problems for desktop users in current?
> Can anybody suggest why this happens?

You're running some very large programs that causes a lot of very
visible context switching and probably some paging too (especially when
your "cvs upates" and compiles and such compete for I/O and metadata
buffer space).

If your Xserver and very little else were running on a workstation, and
all that other goo was running on some server somewhere, then things
would likely be somewhat better.  At least then your mouse wouldn't
freeze up.

You can't expect to be able to context switch through a half dozen
monster applications, all while running high-I/O and CPU loads for
"background" tasks, and not get some "jumpiness" from the most visible
one of them, especially if you're even the tiniest bit shy on RAM.
(have you ever looked at what really happens when you scoot the mouse
around so that it touches large parts of a whole bunch of busy windows,
i.e. windows with lots of context sensitive areas?)

I can run multiple "cvs update", "make package", and bunches of other
applications like cricket and netsaint and various SNMP tools, even with
relatively little RAM (i.e. my build machine pages a fair bit) and on a
system with quite slow disks (just a pair of IDE's), and I don't see any
_serious_ degradation of performance.  I'm running kernels that do not
have some of the newer sysctls for tuning the VM, though I have tuned
the kernel directly somewhat, and I get amazingly good response time
from my shell prompt even when the load average is up to 15 or 20 or so.

I've never really been happy with the performance of the Xserver and
various X11 applications (not even xterm) if I'm running them all on the
same machine where I'm trying to get some "real" computing and I/O
activity accomplished (eg. compiling etc.), regardless of what OS it's

								Greg A. Woods

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