How to optimize a RAM-only (swapless) system?

Von Fugal von at fugal.net
Wed Dec 22 11:52:35 MST 2010


<quote name="John McCabe-Dansted" date="Thu, 23 Dec 2010 at 02:22 +0800">
> There has been research into heuristics that allow one to get the best
> of compressed ram and disk based swap device, providing performance
> that is never worse than disk swap (minus 2% overhead or so). Also
> simply compressing the pages being swapped out could be useful for
> reducing the number of writes to SSD based swap. However it seems that
> neither of these will be supported by compcache in the short term.

It really should sit as an in-between swap and memory place. Recently
"swapped" pages should go straight to compcache, evicting pages if
necessary *from* compcache to disk. That would be ideal. I don't know if
the kernel devs would ever want to futz with the kernel that much,
though.

I wonder why nobody has done compression on regular swap yet. I mean,
the HUGE downside of swap is disk time, compressing the data on the disk
would at least marginally speed up access time to that swapped data.

> One area compcache is already useful is in LiveCDs, for example it is
> used by Ubuntu to reduce the amount of memory need to install from the
> LiveCD.

Yes, very cool!
-- 
Von Fugal
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