Re: [squid-users] Large Files and Reverse proxy

On Friday 29 August 2008 13:41:14 Amos Jeffries wrote:
> Simon Waters wrote:
> > On Friday 29 August 2008 03:40:21 Amos Jeffries wrote:
> >>> For various reasons we have a number of multimedia files on this end of
> >>> the
> >>> connection, all large, and all with no explicit expiry information
> >>> (which I
> >>> can adjust if it helps).
> >>
> >> That will help. Enormously. The longer it can be explicitly known
> >> cacheable the better (RRC states only up to a year though).
> >
> > Can I ask why? Is the default "LRU" or "heap LFUDA" policy concerned with
> > expiry dates.
>
> With known expiry info, squid can calculate fresh/stale properly.
> Without it Squid has to estimate and periodically refreshes the object.
>
> The LRU/LFUDA algorithms are only related to garbage collection on
> objects in the cache.

Perhaps I wasn't clear.

I don't care if Squid does a refresh query for an 8MB object, indeed I'm happy
for it to check freshness every time such an object is fetched if needed to
comply with HTTP RFCs, I was just concerned that Squid is fetching the whole
8MB file many times a day.

It may be Squid is doing a sensible thing with the available resources!

But when I see the whole 8MB file shipped, at one point with a 15 seconds
interval between them to the proxy, I do wonder how it became the LRU of 17GB
of data in 15 seconds (our proxy isn't THAT busy), and whether I'm missing
something basic about the performance of the cache.
Received on Fri Aug 29 2008 - 13:08:49 MDT