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#200253 - 24/01/2004 17:03 RAM Compression?
mcomb
pooh-bah

Registered: 31/08/1999
Posts: 1649
Loc: San Carlos, CA
So here is a crazy thought I just had while thinking about the low memory issues some empeg users are having with large hard drives and/or third party programs running on the empeg. Would it be possible for the linux kernel to automatically compress and decompress the contents of RAM? If this worked it seems like we could make the empeg appear to have more RAM than it actually does. It even seems like there is some existing linux code to do this although for newer versions of the kernel. Thoughts?

-Mike
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#200254 - 24/01/2004 17:14 Re: RAM Compression? [Re: mcomb]
Taym
carpal tunnel

Registered: 18/06/2001
Posts: 2504
Loc: Roma, Italy
It sounds as an excellent idea! So much for a comment coming from a linux-imparied one as I am
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MK2a #040103216 * 100Gb *All/Colors* Radio * 3.0a11 * Hijack = taympeg

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#200255 - 24/01/2004 18:35 Re: RAM Compression? [Re: mcomb]
mlord
carpal tunnel

Registered: 29/08/2000
Posts: 14478
Loc: Canada
Mmm.. the player apparently locks down all of its memory, to prevent paging, which would also prevent the compression scheme from kicking in.

Of course, we could hack the kernel to ignore the locking..

Cheers

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#200256 - 26/01/2004 16:50 Re: RAM Compression? [Re: mcomb]
siberia37
old hand

Registered: 09/01/2002
Posts: 702
Loc: Tacoma,WA
Of course if the player is buffering compressed audio into memory then trying to compress it again will just be a waste of processing power. This might be good to experiment with, however.

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#200257 - 26/01/2004 19:27 Re: RAM Compression? [Re: siberia37]
andy
carpal tunnel

Registered: 10/06/1999
Posts: 5914
Loc: Wivenhoe, Essex, UK
Even if it is buffering uncompressed audio I suspect the result will be much the same. That said, some people do have very tight memory constraints, so I guess even a few percent might help them.
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#200258 - 26/01/2004 19:42 Re: RAM Compression? [Re: siberia37]
mcomb
pooh-bah

Registered: 31/08/1999
Posts: 1649
Loc: San Carlos, CA
Of course if the player is buffering compressed audio into memory then trying to compress it again will just be a waste of processing power

True, but I get the impression that the player stores a copy of the fid database in memory. If that is correct it is probably at least a couple megs on any decent sized player and ought to compress very well (mostly text) unless it is already in a compressed format. Anyway, getting this to work is probably beyond my skills, but I thought it might interest our resident kernel hackers if they are bored some day.

-Mike
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EmpMenuX - ext3 filesystem - Empeg iTunes integration

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#200259 - 26/01/2004 23:35 Re: RAM Compression? [Re: mcomb]
Daria
carpal tunnel

Registered: 24/01/2002
Posts: 3937
Loc: Providence, RI
True, but I get the impression that the player stores a copy of the fid database in memory.


You need a TiVo cachecard!

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#200260 - 27/01/2004 02:38 Re: RAM Compression? [Re: mcomb]
Roger
carpal tunnel

Registered: 18/01/2000
Posts: 5680
Loc: London, UK
I get the impression that the player stores a copy of the fid database in memory.

It does. And you can probably compress it reasonably well. The Karma database uses a more efficient database scheme, so maybe that'll turn up in one of the later v3.0 alphas or betas.
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