Messages in this thread | | | Date | Mon, 28 Apr 2003 22:58:46 -0400 | From | rmoser <> | Subject | Re: Swap Compression |
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On 4/28/2003 at 6:25 PM Timothy Miller wrote:
>rmoser wrote: > >>So what's the best way to do this? I was originally thinking like this: >> >>Grab some swap data >>Stuff it into fcomp_push() >>When you have 100k of data, seal it up >>Write that 100k block >> >>But does swap compress in 64k blocks? 80x86 has 64k segments. >>The calculation for compression performance loss, 256/size_of_input, >>gives a loss of 0.003906 (0.3906%) for a dataset 65536 bytes long. >>So would it be better to just compress segments, whatever size they >>may be, and index those? This would, of course, be much more efficient >>in terms of finding the data to uncompress. (And system dependant) >> >> >We're not using DOS here. x86 has arbitrarily-sized segments. It is >the PAGES you want to swap, and they are typically 4k. > > >BTW, I see swap compression as being more valuable for over-loaded >servers than for PDA's. Yes, I see the advantage for a PDA, but you >only get any significant benefit out of this if you have the horsepower >and RAM required for doing heavy-weight compression. If you can't >compress a page very much, you don't benefit much from swapping it to RAM.
Feh. Selectable compression is the eventual goal. If you want serious heavy-weight compression, go with fcomp2. Ahh heck I'll attatch the .plan file for fcomp2; this is rediculously RAM and CPU intensive in good implimentation, so don't even think for a second that you'll want to use this on your cpu-overloaded boxen.
And no implimenting this right away, it's too much to code!
--Bluefox Icy [unhandled content-type:application/octet-stream]
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