Re: pre6 VM issues

[Marcelo Tosatti]

On Tue, 9 Oct 2001, BALBIR SINGH wrote:

> Most of the traditional unices maintained a pool for each subsystem
> (this is really useful when u have the memory to spare), so not matter
> what they use memory only from their pool (and if needed peek outside),
> but nobody else used the memory from the pool.
> 
> I have seen cases where, I have run out of physical memory on my system,
> so I try to log in using the serial console, but since the serial driver
> does get_free_page (this most likely fails) and the driver complains back.
> So, I had suggested a while back that important subsystems should maintain
> their own pool (it will take a new thread to discuss the right size of
> each pool).
> 
> Why can't Linux follow the same approach? especially on systems with a lot
> of memory.

There is nothing which avoids us from doing that (there is one reserved
pool I remeber right now: the highmem bounce buffering pool, but that one
is a special case due to the way Linux does IO in high memory and its only
needed on _real_ emergencies --- it will be removed in 2.5, I hope).

In general, its a better approach to share the memory and have a unified
pool. If a given subsystem is not using its own "reversed" memory, another
subsystems can use it.

The problem we are seeing now can be fixed even without the reserved
pools.