Re: HTTP Accelerator algorithm

The notion of the accelerator is that Squid can often server pages directly
from memory, and failing that, it doesn't have all sorts of authentication
and checking overhead, as you'd have with Apache (especially if you haven't
spent time tuning things like symlink handling and the like). Even on
dynamic sites, this can be very useful for things like static images or
downloads - in fact, in such cases it can be _especially_ useful, because
the dynamic html generation generally requires a fairly heavyweight server,
which can be wasted if it's also required to serve static content.

Of course, this only works if items can get into the cache. If items never
get into the cache, you'll see a net slowdown, because you've added extra
processing in the middle. If you aren't telling the accelerator how to
cache things using Expires headers, it's very likely that it's not caching
anything.

Our heavily dynamic Apache-based servers use:

ExpiresActive On
ExpiresByType image/gif "access plus 4 hours"
ExpiresByType image/jpeg "access plus 4 hours"
ExpiresByType application/octet-stream "access plus 4 hours"

Our Squid http accelerator serves in excess of 50% of the requests out of
cache.

Later,
scott

----- Original Message -----
From: Jon Drukman <jsd@gamespot.com>
To: <squid-users@ircache.net>
Sent: Thursday, July 01, 1999 11:00 AM
Subject: HTTP Accelerator algorithm

> Can someone explain the HTTP Accelerator mode algorithm to me? I assumed
> that Squid would only request files from the origin server intermittently,
> but it appears to be requesting the same files constantly. We do not use
> Expires headers on the origin, so that's not forcing squid to reload.
>
> Fortunately the machine being accelerated is on a 100Mbit switched network
> with the Squid server, but I had wanted to put some Squid boxes overseas
to
> accelerate content for our International licensees. If it has to make a
> transatlantic request for every object I don't really see the advantage.
>
>
> Jon Drukman
> Director Of Technology
> GameSpot
>
Received on Thu Jul 01 1999 - 12:32:09 MDT