Its going to depend a lot on your data model but 5-6k is on the low end of what I would expect. N=RF=2 is not really something I would recommend. That said 93GB is not much data so the bottleneck may exist more in your data model, queries, or client.
What profiler are you using? The cpu on the select/read is marked as RUNNABLE but its really more of a wait state that may throw some profilers off, it may be a red haring. --- Chris Lohfink On Sep 22, 2014, at 11:39 AM, Leleu Eric <eric.le...@worldline.com> wrote: > Hi, > > > I’m currently testing Cassandra 2.0.9 (and since the last week 2.1) under > some read heavy load… > > I have 2 cassandra nodes (RF : 2) running under CentOS 6 with 16GB of RAM and > 8 Cores. > I have around 93GB of data per node (one Disk of 300GB with SAS interface and > a Rotational Speed of 10500) > > I have 300 active client threads and they request the C* nodes with a > Consitency level set to ONE (I’m using the CQL datastax driver). > > During my tests I saw a lot of CPU consumption (70% user / 6%sys / 4% iowait > / 20%idle). > C* nodes respond to around 5000 op/s (sometime up to 6000op/s) > > I try to profile a node and at the first look, 60% of the CPU is passed in > the “sun.nio.ch” package. (SelectorImpl.select or Channel.read) > > I know that Benchmark results are highly dependent of the Dataset and use > cases, but according to my point of view this CPU consumption is normal > according to the load. > Someone can confirm that point ? > According to my Hardware configuration, can I expect to have more than 6000 > read op/s ? > > > Regards, > Eric > > > > > > > Ce message et les pièces jointes sont confidentiels et réservés à l'usage > exclusif de ses destinataires. Il peut également être protégé par le secret > professionnel. Si vous recevez ce message par erreur, merci d'en avertir > immédiatement l'expéditeur et de le détruire. L'intégrité du message ne > pouvant être assurée sur Internet, la responsabilité de Worldline ne pourra > être recherchée quant au contenu de ce message. Bien que les meilleurs > efforts soient faits pour maintenir cette transmission exempte de tout virus, > l'expéditeur ne donne aucune garantie à cet égard et sa responsabilité ne > saurait être recherchée pour tout dommage résultant d'un virus transmis. > > This e-mail and the documents attached are confidential and intended solely > for the addressee; it may also be privileged. If you receive this e-mail in > error, please notify the sender immediately and destroy it. As its integrity > cannot be secured on the Internet, the Worldline liability cannot be > triggered for the message content. Although the sender endeavours to maintain > a computer virus-free network, the sender does not warrant that this > transmission is virus-free and will not be liable for any damages resulting > from any virus transmitted.
