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

From: Andreas Hartmann (
Date: Sat Jan 05 2002 - 10:09:34 EST

M. Edward (Ed) Borasky wrote:

> On Sat, 5 Jan 2002, Andreas Hartmann wrote:
>>I don't like special test-programs. They seldom show up the reality.
>>What we need is a kernel that behaves fine in reality - not in
>>testcases. And before starting the test, take care, that most of ram
>>is already used for cache or buffers or applications.
> OK, here's some pseduo-code for a real-world test case. I haven't had a
> chance to code it up, but I'm guessing I know what it's going to do. I'd
> *love* to be proved wrong :).

I would like to try it with the oom-patch, which needed less swap in my
tests. It could be a good test to verify the results of the rsync-test.

> # build and boot a kernel with "Magic SysRq" turned on
> # echo 1 > /proc/sys/kernel/sysrq
> # fire up "nice --19 top" as "root"
> # read "MemTotal" from /proc/meminfo
> # now start the next two jobs concurrently
> # write a disk file with "MemTotal" data or more in it
> # perform a 2D in-place FFT of total size at least "MemTotal/2" but less
> # than "MemTotal"
> Watch the "top" window like a hawk. "Cached" will grow because of the
> disk write and "free" will drop because the page cache is growing and
> the 2D FFT is using *its* memory.

Could you please tell me a programm, that does 2D FFT? I would like to
do this test, too!

Andreas Hartmann

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