gc-linux-devel

[Gc-linux-devel] Compressed VM

[Dead2 <de...@ci...>]

Just wanted to point out the possibility of running
"linuxcompressed". First and foremost this would
benefit us by making the swap compressed.
Secondly it can also compress parts of the main
memory.

It is developed fro the i386 platform, but is also
reported to be working (at least swap part) fully
on other archs. It does not contain much i386
specific code, that's just what the developers use.

On the GC, if this could take our 16MB swap to
effectively be 20-50MB (depending on contents),
it would surely mean a world of difference.

The memory part is a bit different. You have to
specify how much of the memory is to be
compressed. 50/50 is usually a good start.
So, 12MB compressed ram would probably be
able to contain 20-30MB too, without beeing
overly optimistic. (24-48 is what I'm thinking)

So, in effect this would enable us to atleast double
the memory load on the GC..  And that is a very
nice increase on such a memory starved box.

http://linuxcompressed.sourceforge.net/

-=Dead2=-

Re: [Gc-linux-devel] Compressed VM

[Michael S. <st...@in...>]

Sounds *very* interesting, but the kernel patches seem to be for 2.4 
only, and we're based on 2.6. :-/

   Michael

On 16.02.2004, at 11:26, Dead2 wrote:

> Just wanted to point out the possibility of running
> "linuxcompressed". First and foremost this would
> benefit us by making the swap compressed.
> Secondly it can also compress parts of the main
> memory.
>
> It is developed fro the i386 platform, but is also
> reported to be working (at least swap part) fully
> on other archs. It does not contain much i386
> specific code, that's just what the developers use.
>
> On the GC, if this could take our 16MB swap to
> effectively be 20-50MB (depending on contents),
> it would surely mean a world of difference.
>
> The memory part is a bit different. You have to
> specify how much of the memory is to be
> compressed. 50/50 is usually a good start.
> So, 12MB compressed ram would probably be
> able to contain 20-30MB too, without beeing
> overly optimistic. (24-48 is what I'm thinking)
>
> So, in effect this would enable us to atleast double
> the memory load on the GC..  And that is a very
> nice increase on such a memory starved box.
>
> http://linuxcompressed.sourceforge.net/
>
> -=Dead2=-
>
>
>
>
>
> -------------------------------------------------------
> SF.Net is sponsored by: Speed Start Your Linux Apps Now.
> Build and deploy apps & Web services for Linux with
> a free DVD software kit from IBM. Click Now!
> http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click
> _______________________________________________
> Gc-linux-devel mailing list
> Gc-...@li...
> https://lists.sourceforge.net/lists/listinfo/gc-linux-devel
>

[Gc-linux-devel] Re: Compressed VM

[Hans K. R. <hk...@ci...>]

> Sounds *very* interesting, but the kernel patches seem to be for 2.4
> only, and we're based on 2.6. :-/

That's a bummer..  I wonder how much work it would be to port
the compressed swap part to 2.6.

Anyways..  I think another aproach might be possible..
The question is: Is the 16mb destined for swap usage using MTD drivers?
(I guess this it 2x8MB flash cards that you put in the front of the GC,
right?)

If so, I assume it is MTD capable.
That means you can format them with the JFFS2 filesystem.
And then you can put swap-FILES (2.6 supports that i think) on them.

JFFS2 is basically a read+write filesystem optimized for usage on small
flash chips, and also incorporates compression.

You need to enable MTD, then the JFFS2 selection appears under
"Misc filesystems" in the 2.6 kernel config.

I hope this leads somewhere.. =)

-=Dead2=-

Re: [Gc-linux-devel] Re: Compressed VM

[Michael S. <st...@in...>]

On 16.02.2004, at 13:29, Hans K. Rosbach wrote:
> Anyways..  I think another aproach might be possible..
> The question is: Is the 16mb destined for swap usage using MTD drivers?
> (I guess this it 2x8MB flash cards that you put in the front of the GC,
> right?)

You mean the ARAM? It's just RAM chips; we can write block device 
drivers for it and use it like a hard disk or anything.

> If so, I assume it is MTD capable.
> That means you can format them with the JFFS2 filesystem.
> And then you can put swap-FILES (2.6 supports that i think) on them.
>
> JFFS2 is basically a read+write filesystem optimized for usage on small
> flash chips, and also incorporates compression.

It does?

> You need to enable MTD, then the JFFS2 selection appears under
> "Misc filesystems" in the 2.6 kernel config.
>
> I hope this leads somewhere.. =)

Sounds interesting, but somehow I doubt JFFS2 can properly compress a 
swap file.

Porting compressed swap to 2.6 would be the best for all.

   Michael