Re: Does process need to have a kernel-side stack all the time?

[Arjan van de Ven]

On Wed, 16 Apr 2008 15:59:01 +0200
Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:

> 
> > well that and the fact that RH had customers who had major issues
> > at fewer threads with 8Kb versus fragmentation.
> > on 32 bit with a bunch of ram, there's just not enough lowmem
> > around to not have it fragmented to hell and back.
> 
> 2.6 VM has much more aggressive defrag heuristics than 2.4. That is
> what I meant with likely obsolete.

it's a question of very simple math though; both the space and the
amount of other pinnings mean you run into a wall.

2.6 is no doubt better, for sure it's better in freeing up memory etc.
It just can't be good enough.

(just to be clear, customers do run 30k threads workloads on 16Mb machines that
also have a sizable inode and dentry cache. you just cannot defragment that to the point
that you can use 8k stacks).




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