Re: Alternative Squid Filesystem

On Sat, May 27, 2000, Henrik Nordstrom wrote:
> Found this lying around in a pool of old emails, not sure if I have
> responded.
>
> Your ideas seems very similar to the ideas I was toying around with some
> year ago. Part of it has been implemented by Eric Stern in the COSS
> object storage available in the current Squid CVS sources.
>
> For an archive of old notes see http://squid.sourceforge.net/hno/
>

The difference here is that the object store being proposed isn't an
exact LRU, its an average LRU. I actually like the idea. After some more
preparation work is done with the current codebase so it will benefit
from this kind of filesystem.

Adrian

> Alexander Pennace wrote:
> >
> > Greetings,
> >
> > Over the weekend I've been toying around with a different approach to
> > managing Squid cache storage.
> >
> > The main problem appears to be keeping fragmentation down while still
> > maintaining a reasonable LRU replacement policy. If we say that the
> > replacement policy doesn't have to be a perfect LRU policy, then a
> > number of interesting options open up to capitalize on that sacrifice.
> >
> > Imagine a Squid spool as a large linear file. This file is made up of
> > contiguous objects for the cache. Adding new objects to this spool is
> > simple: if there is enough free space for the object add it there.
> > Otherwise consider each object or contiguous group of objects that if
> > freed will yield enough space for this new object, and replace the
> > object or group of objects with the highest average used-age.
> >
> > Thats essentially my idea. I'm still considering other additions, like
> > maintaining timing data to get an idea of which contiguous blocks from
> > disk are the fastest to read or write to, but those don't directly
> > impact my basic theory.
> >
> > ---------------------------------------------------------------
> >
> > Part 1.2 Type: application/pgp-signature

-- 
Adrian Chadd			Build a man a fire, and he's warm for the
<adrian@creative.net.au>	rest of the evening. Set a man on fire and
				he's warm for the rest of his life.