I just tried running the same multi_get against cassandra 1000 times, assuming that that'd force it in to cache.
I'm definitely seeing a 5-10ms improvement, but it's still looking like 20-30ms on average. Would you expect it to be faster than that? - James On Wed, Mar 31, 2010 at 11:44 AM, Jonathan Ellis <jbel...@gmail.com> wrote: > But then you'd still be caching the same things memcached is, so > unless you have a lot more ram you'll presumably miss the same rows > too. > > The only 2-layer approach that makes sense to me would be to have > cassandra keys cache at 100% behind memcached for the actual rows, > which will actually reduce the penalty for a memcache miss by > half-ish. > > On Wed, Mar 31, 2010 at 1:32 PM, David Strauss <da...@fourkitchens.com> > wrote: > > Or, if faking memcached misses is too high a price to pay, queue some > > proportion of the reads to replay asynchronously against Cassandra. > > > > On Wed, 2010-03-31 at 11:04 -0500, Jonathan Ellis wrote: > >> Can you redirect some of the reads from memcache to cassandra? Sounds > >> like the cache isn't getting warmed up. > >> > >> On Wed, Mar 31, 2010 at 11:01 AM, James Golick <jamesgol...@gmail.com> > wrote: > >> > I'm testing on the live cluster, but most of the production reads are > being > >> > served by the cache. It's definitely the right CF. > >> > > >> > On Wed, Mar 31, 2010 at 8:30 AM, Jonathan Ellis <jbel...@gmail.com> > wrote: > >> >> > >> >> On Wed, Mar 31, 2010 at 12:01 AM, James Golick < > jamesgol...@gmail.com> > >> >> wrote: > >> >> > Okay, so now my row cache hit rate jumps between 1.0, 99.5, 95.6, > and > >> >> > NaN. > >> >> > Seems like that stat is a little broken. > >> >> > >> >> Sounds like you aren't getting enough requests for the > >> >> getRecentHitRate to make sense. use getHits / getRequests. > >> >> > >> >> But if you aren't getting enough requests for getRecentHitRate, are > >> >> you sure you're tuning the cache on the right CF for your 35ms test? > >> >> Are you testing live? If not, what's your methodology here? > >> >> > >> >> -Jonathan > >> > > >> > > > > > > > > > >
