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.
