Re: 2.4.0-test10 Sluggish After Load

[Christoph Rohland <cr@sap.com>]

Hi Rik,

On Wed, 1 Nov 2000, Rik van Riel wrote:
> The 2.4 VM is basically pretty good when you're not
> thrashing and has efficient management of the VM until
> your working set reaches the size of physical memory.
> 
> But once you hit the thrashing point, the VM falls
> flat on its face. This is a nasty surprise to many
> people and I am working on (trivial) thrashing control,
> but it's not there yet (and not all that important).

I looked into this argument a little bit further: 
In my usual stress tests 12 processes select a random memory object
out of 15 to mmap() or shmat() it and then access it serially. Each
segment is 666000000 bytes and I have 8GB of memory. So at one time
there are at most 666000000*12 bytes = 7.45GB memory attached and in
use. So I do not see that the machine qualifies as thrashing. Of
course the memory pressure is very high all the time since we have to
swap out unused segments.

But the current VM does not behave good at all on that load.

Greetings
		Christoph

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