On Wed, 5 Nov 2008, David Gwynne wrote:

> be done in a very short time. perhaps you can amortize that cost by
> doing it when the data from userland makes it into the kernel. another
> idea could be doing the compression when you reach a relatively low
> threshold of uncompressed data in the cache. ie, as soon as you get
> 1MB of data in the cache, compress it then, rather than waiting till
> you have 200MB of data in the cache that needs to be compressed RIGHT
> NOW.

This is counter-productive.  ZFS's lazy compression approach ends up 
doing a lot less compression in the common case where files are 
updated multiple times before ZFS decides to write to disk.  If your 
advice is followed, then every write will involve compression, rather 
than the summation of perhaps thousands of writes.

Bob
======================================
Bob Friesenhahn
[EMAIL PROTECTED], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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