Re: swapspace layout improvements advocacy

[Andrew Morton <akpm@osdl.org>]

Tim Schmielau <tim@physik3.uni-rostock.de> wrote:
>
> I recently found out that 2.6 kernels degrade horribly when going into 
>  swap. On my dual PIII-850 with as little as 256 mb ram, I can easily 
>  demonstrate that by opening about 40-50 instances of konquerer with large 
>  tables, many images and such things. When the machine is into 80-120 mb of 
>  the 256 mb swap partition, it becomes almost unusable. Even the desktop 
>  background picture needs ~20sec to update, not to talk about any windows' 
>  contents. And you can literally hear the reason for it: the harddisk is 
>  seeking like crazy.
> 
>  I've applied Ingo Molnars swapspace-layout-improvements-2.6.9-rc1-bk12-A1
>  port of the patch to a 2.6.11-rc1 kernel, and it handles the same workload 
>  much smoother. It's slow, but you can work with it.

Well I'm surprised.  I ran a couple of silly tests and wasn't able to
demonstrate any benefit.  But I didn't persist at all due to general inbox
overload :(

>  I just wonder why noone else complained yet.

They're all too polite?

> Are systems with tight memory constraints so uncommon these days?

Relatively, but I think we do have some fairly technical people on this
list who push their systems that hard, which is appreciated.  I'll add the
patch to the -mm lineup for a while..