> ramak> Also i was thinking about one of the other suggestions that
> ramak> was made regarding the compression of a page(s) to a portion
> ramak> of the RAM, and uncompress it as part of the swap back in.
>
> I think there is a product called "RamDoubler" for the Macintosh
> which implements a two-stage virtual memory system:
> 1) As usual, there are a bunch of uncompressed pages in use.
> 2) A first-level swapout compresses a page into an area in memory.
> I think RamDoubler allocates more than half of memory to holding
> compressed versions of swapped-out pages.
> 3) A second-level swapout writes the (compressed?) page to disk.
>
> If your process has a working set which is a bit too large to fit
> in physical memory, but which, compressed, fits in physical memory,
> then it may run a bit faster since there is no disk I/O. For lots
> of applications, single-process latency is the most important
> measure of performance.
Yes, at one time I ran MacOS, along with RamDoubler. It does compression
of RAM of some sort. It worked quite a bit better than the (quite crappy)
default MacOS VM implementation.
>
> My guess is that a compressed swap would be most useful in an
> embedded application which has no hard disk and is trying to get
> by on the minimum possible RAM. In this situation, you would be
> back to a single-level swap system. Does anyone know if Linux is
> getting into the embedded world much?
>
Yes, a good number of the kernel developers on the linuxppc-dev list are
using Motorola PowerPC embedded boards. These boards range from Pentium
100 equivalents (100mhz 603e) to 300Mhz PPC 750's (G3's)
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| Troy Benjegerdes | troy@microux.com | hozer@drgw.net |
| Unix is user friendly... You just have to be friendly to it first. |
| This message composed with 100% free software. http://www.gnu.org |
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