Re: swap cache

Prasun Kapoor (prasun@wipinfo.soft.net)
Sat, 19 Dec 1998 18:06:57 -0500 (GMT)


> Linux supports such easily enough; create a ramdisk, create a swapfile
> on the ramdisk, and then activate it.
>
> I do not understand the utility of this design.

Yes, there is indeed no utility of this design if you consign a part of yr
RAM for swapping and this is not what Solaris does. And this doesnt have
anything to do with the memory file system. It is actually the other way
round. Memory file system is implemented on swap.

Solaris has a pseudo file system called swapfs which takes into account
the RAM. The argument given is, there are instances where you may run out
of swap but not RAM!! ( Extreme case being that a malloc() would fail on a
system with 0 swap on disk and 1Gig of RAM :) ). So it takes into account
the avilable memory before telling the user that it has run out of swap.
It doesnt actually swap to RAM.

For full details on this implementation refer to following articles:

http://www.sunworld.com/swol-12-1997/swol-12-insidesolaris.html
http://www.sunworld.com/sunworldonline/swol-01-1998/swol-01-insidesolaris.html

prasun
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