Re: Two naive questions and a suggestion

[Rik van Riel <H.H.vanRiel@phys.uu.nl>]

On 24 Nov 1998 jfm2@club-internet.fr wrote:

> Agreed, the important feature is the stopping one of the processes
> when critically short of memory.  Swapping is only a trick for
> getting more bandwidth at the expenses of pushing in an out of
> memory a greater amount of process space so there is no proof it is
> faster than letting other processes steal memory page by page from
> the now stopped process. 

When the mythical swapin readahead will be merged, we can
gain some ungodly amount of speed almost for free. I don't
know if we'll ever implement the scheduling tricks...

I do have a few ideas for the scheduling stuff though, with
RSS limits (we can safely implement those when the swap cache
trick is implemented) and the keeping of a few statistics,
we will be able to implement the swapping tricks.

Without swapin readahead, we'll be unable to implement them
properly however :(

> > > And now we are at it: in 2.0 I found a deamon can be killed by the
> > > system if it runs out of VM.  
> > 
> > Same on any BSD.
> 
> Say the Web or database server can be deemed important enough for it
> not being killed just because some dim witt is playing with the GIMP
> at the console and the GIMP has allocated 80 Megs.

I sounds remarkably like you want my Out Of Memory killer
patch. This patch tries to remove the randomness in killing
a process when you're OOM by carefully selecting a process
based on a lot of different factors (size, age, CPU used,
suid, root, IOPL, etc).

It needs to be cleaned up, ported to 2.1.129 and improved
a little bit though... After that it should be ready for
inclusion in the kernel.

cheers,

Rik -- slowly getting used to dvorak kbd layout...
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| Linux memory management tour guide.        H.H.vanRiel@phys.uu.nl |
| Scouting Vries cubscout leader.      http://www.phys.uu.nl/~riel/ |
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