Best way to setup 128MB box that can only cache 64MB

Best way to setup 128MB box that can only cache 64MB

[Robert Lowery]

Hi,

I know most people are now having fun on 2GB+ SMP Mega666 processor systems
these days ;), But unfortunately, I still only have a Pentium 233MMX system
as my firewall with 128MB RAM with the Intel 430FX chip which can only cache
the first 64MB.

There have been lots of discussions over the years on this topic, but I
could not find any definitive answers. How should I set this box up to get
the best performance?

Searching around on google, I found references to the slram patch
(originally found here http://www.andrew.cmu.edu/~keryan/slram/) to allow
the slower (uncached) RAM to be used as SWAP, but cannot find a current
location of this patch.  Is this patch still required if I want to use the
top 64MB of RAM as swap? (as of 2.4.13) or is there some other way to
achieve this?

I guess there is a tradeoff.  If I use the entire memory as is, there will
be an xx% impact on the system as it loads from the top down.  If I can find
(and decide to use) the slram patch, then there will be lots of copying
(swapping) of memory to/from cached/uncached memory.  At least it's faster
than diskio I guess.

Does anyone have any suggestions/recommendations regarding this age old
topic?

-Robert

Re: Best way to setup 128MB box that can only cache 64MB

[Ryan Cumming]

On November 1, 2001 20:00, Robert Lowery wrote:
> Hi,
>
> I know most people are now having fun on 2GB+ SMP Mega666 processor systems
> these days ;), But unfortunately, I still only have a Pentium 233MMX system
> as my firewall with 128MB RAM with the Intel 430FX chip which can only
> cache the first 64MB.
>
> There have been lots of discussions over the years on this topic, but I
> could not find any definitive answers. How should I set this box up to get
> the best performance?

I'm curious if zones could be of any benefit in this situation. Could the 
kernel be told to use memory over 64megs only if significant pressure is put 
on the VM, sort of like how we treat the DMA zone now? I suspect this will 
have much lower overhead than using the top 64megs as swap. Any MM gods want 
to comment?

-Ryan

RE: Best way to setup 128MB box that can only cache 64MB

[Robert Lowery]

I should have also mentioned that I use this box for playing DVD's (with a
Hollywood+ card) and MP3's.

Of course linux does not need 128MB for a firewall.

-Rob

P.S. The memory zones stuff sounds very interesting and I am looking forward
to any input from the MM gods ;)

> -----Original Message-----
> From: Ryan Cumming [mailto:bodnar42@phalynx.dhs.org]
> Sent: Friday, November 02, 2001 4:53 PM
> To: Robert Lowery
> Cc: linux-kernel@vger.kernel.org
> Subject: Re: Best way to setup 128MB box that can only cache 64MB
> 
> 
> On November 1, 2001 20:00, Robert Lowery wrote:
> > Hi,
> >
> > I know most people are now having fun on 2GB+ SMP Mega666 
> processor systems
> > these days ;), But unfortunately, I still only have a 
> Pentium 233MMX system
> > as my firewall with 128MB RAM with the Intel 430FX chip 
> which can only
> > cache the first 64MB.
> >
> > There have been lots of discussions over the years on this 
> topic, but I
> > could not find any definitive answers. How should I set 
> this box up to get
> > the best performance?
> 
> I'm curious if zones could be of any benefit in this 
> situation. Could the 
> kernel be told to use memory over 64megs only if significant 
> pressure is put 
> on the VM, sort of like how we treat the DMA zone now? I 
> suspect this will 
> have much lower overhead than using the top 64megs as swap. 
> Any MM gods want 
> to comment?
> 
> -Ryan
>