Hi, Thanks for providing this information.
"- Under normal circumstances, when a record expires, all clients querying that record suffer (unnecessary) latency while the record is being re-queried upstream. Fixing this was a convenient benefit." Do you have specific metrics to measure/evaluate this benefit? BR, Daniel On Wed, Nov 6, 2013 at 10:50 PM, Brian Somers <bsom...@opendns.com> wrote: > Hi, > > I mentioned at the dnsop talk at IETF88 yesterday that I have some > (hopefully) useful information regarding W.C.A. Wijngaards' prefetch work. > > At OpenDNS, we implemented the same thing some months ago (without knowing > about this work) with the following differences: > - Our HAMMER_TIME is set to 3 seconds > - Our STOP is hardwired as HAMMER_TIME + 1 > > We saw similar non-results in our graphs - at ~50 billion queries per day, > prefetch didn't change anything.... However, there were two other issues > addressed: > - Under normal circumstances, when a record expires, all clients querying > that record suffer (unnecessary) latency while the record is being > re-queried upstream. Fixing this was a convenient benefit. > - Because our resolvers run multiple threads sharing the same cache, > previously, a popular record expiration would tend to result in an upstream > query from *each* thread. This was the issue we wanted to address. > > You could argue that our implementation should be clever enough to > piggy-back the upstream queries from different threads (one query, multiple > clients on multiple threads waiting for the response), but having the > threads interact/contend against eachother for more than just cache > lookups/updates is undesirable at higher loads. > > -- > Brian Somers > bsom...@opendns.com > > > > > > _______________________________________________ > DNSOP mailing list > DNSOP@ietf.org > https://www.ietf.org/mailman/listinfo/dnsop > > -- Daniel Migault Orange Labs -- Security +33 6 70 72 69 58
_______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
