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From Chris Lohfink <>
Subject Re: CPU consumption of Cassandra
Date Mon, 22 Sep 2014 20:03:24 GMT
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 <> 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 “”
package. ( or
> 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
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