Re: experiences beyond 4 GB RAM with 2.4.22

[Jens Axboe <axboe@suse.de>]

On Wed, Sep 17 2003, Marcelo Tosatti wrote:
> 
> 
> On Wed, 17 Sep 2003, Jens Axboe wrote:
> 
> > On Wed, Sep 17 2003, Alan Cox wrote:
> > > On Maw, 2003-09-16 at 20:58, Olivier Galibert wrote:
> > > > On Tue, Sep 16, 2003 at 04:29:02PM +0100, Alan Cox wrote:
> > > > > The kernel has no idea what you will do with given ram. It does try to
> > > > > make some guesses but you are basically trying to paper over hardware
> > > > > limits.
> > > > 
> > > > Is there a way to specifically turn that ram into a tmpfs though?
> > > 
> > > 
> > > Something like z2ram copied and hacked a little to kmap the blocks it
> > > wants would give you a block device you could use for swap or for /tmp.
> > > Im not sure tmpfs would work here
> > 
> > Aditionally, you need GFP_DMA32 or similar. Would also alleviate the
> > nasty pressure on ZONE_NORMAL which is often quite stressed.
> 
> IMO such GFP_DMA32 flag is a bit intrusive for 2.4, isnt it?

Not really, it's just an extra zone. Maybe I can dig such a patch up, I
had one for 2.4.2-pre something...

> What has been done in 2.6 in respect to the excessive normal zone 
> pressure and bounce buffering problems? 

Nothing, afaic. 2.6 isn't even completely deadlock free when it comes to
bounce buffering.

-- 
Jens Axboe