Alex Rousskov wrote: > On 10/10/2017 07:50 PM, Victor Sudakov wrote: > > > When updating several almost identical FreeBSD hosts via a > > squid-3.5.27 proxy, I expect to see lots of HITs, because the patches > > on the update server should be identical too. > > > > However, I see lots of TCP_REFRESH_UNMODIFIED lines, and only > > occasional HIT statuses. > > > There are many kinds of "hits": > > * If your primary concern is data transfer/bandwidth usage, then you > should focus on so called byte hits. TCP_REFRESH_UNMODIFIED is > essentially one of those because the origin server sends a tiny > headers-only response to Squid. My primary concern is bandwidth usage. You are saying that the TCP_REFRESH_UNMODIFIED transaction means that the bulk of the data is not transferred from Webserver to Squid, only the headers are fetched? If you look at this line: 1507630625.515 448 212.73.124.12 TCP_REFRESH_UNMODIFIED/200 980593 GET http://update6.freebsd.org/to-10.4-RELEASE/i386/bp/1195d725efce75f0db6317f507d8a9514f35613c7466673a86db23100bd6fa77-c4150431df5b14b15546b3db5e30f2bd2c35d6d52812f057dc101fab20847324 - HIER_DIRECT/198.148.79.66 application/octet-stream There cannot be 980593 bytes of headers? What kind of gigantic header does it make? [dd] > > > The "fetch" HTTP client the freebsd-update utility uses is rather dumb > > and does not send IMS requests (also see below). Could someone please > > explain what is happening here? > > If the client is not sending any conditional headers, then Squid decides > that the previously cached response has expired and needs to be revalidated. > > > > The HTTP replies from the squid cache to the HTTP client are > > "X-Cache-Lookup: MISS from proxy2.sibptus.ru:8080", so these > > TCP_REFRESH_UNMODIFIED statuses seem to be really MISSes and I'm not > > saving traffic on these updates. > > According to your pasted log and HTTP messages, the GET request URL that > resulted an "X-Cache-Lookup: MISS" response header does not match any of > the logged URLs; even the host part of the URL does not match. Of course, there are just unrelated examples. There are thousands of fetches from update*.freebsd.org > To be sure that you are comparing apples to apples, you would need > to log the X-Cache-Lookup response header to access.log (or enable > ALL,2 debugging to see headers and/or collect packet traces). I don't think the freebsd-update cares about the X-Cache-Lookup response, I'm just trying to save bandwidth and don't quite like the result. -- Victor Sudakov, VAS4-RIPE, VAS47-RIPN AS43859 _______________________________________________ squid-users mailing list squid-users@xxxxxxxxxxxxxxxxxxxxx http://lists.squid-cache.org/listinfo/squid-users
