Although low amount of updates, it's possible that you hit a contention
bug. A simple test would be to add multiple Cassandra nodes on the same
physical node (like split your 20 cores to 5 instances of Cassandra). If
you get much higher throughput, then you have an answer..
I don't think a single-instance Cassandra 3.11.2 scales to 20 cores (at
least with the stress-test pattern). There's few known issues in the
write-path at least that prevent scaling with high CPU core count.
- Micke
On 03/12/2018 03:14 PM, onmstester onmstester wrote:
I mentioned that already tested increasing client threads + many
stress-client instances in one node + two stress-client in two
separate nodes, in all of them the sum of throughputs is less than
130K. I've been tuning all aspects of OS and Cassandra (whatever I've
seen in config files!) for two days, still no luck!
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---- On Mon, 12 Mar 2018 16:38:22 +0330 *Jacques-Henri Berthemet
<jacques-henri.berthe...@genesys.com>* wrote ----
What happens if you increase number of client threads?
Can you add another instance of cassandra-stress on another host?
*--*
*Jacques-Henri Berthemet*
*From:* onmstester onmstester [mailto:onmstes...@zoho.com
<mailto:onmstes...@zoho.com>]
*Sent:* Monday, March 12, 2018 12:50 PM
*To:* user <user@cassandra.apache.org
<mailto:user@cassandra.apache.org>>
*Subject:* RE: yet another benchmark bottleneck
no luck even with 320 threads for write
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---- On Mon, 12 Mar 2018 14:44:15 +0330 *Jacques-Henri Berthemet
<jacques-henri.berthe...@genesys.com
<mailto:jacques-henri.berthe...@genesys.com>>* wrote ----
It makes more sense now, 130K is not that bad.
According to cassandra.yaml you should be able to increase
your number of write threads in Cassandra:
# On the other hand, since writes are almost never IO bound,
the ideal
# number of "concurrent_writes" is dependent on the number of
cores in
# your system; (8 * number_of_cores) is a good rule of thumb.
concurrent_reads: 32
concurrent_writes: 32
concurrent_counter_writes: 32
Jumping directly to 160 would be a bit high with spinning
disks, maybe start with 64 just to see if it gets better.
*--*
*Jacques-Henri Berthemet*
*From:*onmstester onmstester [mailto:onmstes...@zoho.com
<mailto:onmstes...@zoho.com>]
*Sent:*Monday, March 12, 2018 12:08 PM
*To:*user <user@cassandra.apache.org
<mailto:user@cassandra.apache.org>>
*Subject:*RE: yet another benchmark bottleneck
RF=1
No errors or warnings.
Actually its 300 Mbit/seconds and 130K OP/seconds. I missed a
'K' in first mail, but anyway! the point is: More than half of
node resources (cpu, mem, disk, network) is unused and i can't
increase write throughput.
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---- On Mon, 12 Mar 2018 14:25:12 +0330 *Jacques-Henri
Berthemet <jacques-henri.berthe...@genesys.com
<mailto:jacques-henri.berthe...@genesys.com>>* wrote ----
Any errors/warning in Cassandra logs? What’s your RF?
Using 300MB/s of network bandwidth for only 130 op/s looks
very high.
*--*
*Jacques-Henri Berthemet*
*From:*onmstester onmstester [mailto:onmstes...@zoho.com
<mailto:onmstes...@zoho.com>]
*Sent:*Monday, March 12, 2018 11:38 AM
*To:*user <user@cassandra.apache.org
<mailto:user@cassandra.apache.org>>
*Subject:*RE: yet another benchmark bottleneck
1.2 TB 15K
latency reported by stress tool is 7.6 ms. disk latency is
2.6 ms
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---- On Mon, 12 Mar 2018 14:02:29 +0330 *Jacques-Henri
Berthemet <jacques-henri.berthe...@genesys.com
<mailto:jacques-henri.berthe...@genesys.com>>* wrote ----
What’s your disk latency? What kind of disk is it?
*--*
*Jacques-Henri Berthemet*
*From:*onmstester onmstester
[mailto:onmstes...@zoho.com <mailto:onmstes...@zoho.com>]
*Sent:*Monday, March 12, 2018 10:48 AM
*To:*user <user@cassandra.apache.org
<mailto:user@cassandra.apache.org>>
*Subject:*Re: yet another benchmark bottleneck
Running two instance of Apache Cassandra on same
server, each having their own commit log disk dis not
help. Sum of cpu/ram usage for both instances would be
less than half of all available resources. disk usage
is less than 20% and network is still less than 300Mb
in Rx.
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---- On Mon, 12 Mar 2018 09:34:26 +0330 *onmstester
onmstester <onmstes...@zoho.com
<mailto:onmstes...@zoho.com>>* wrote ----
Apache-cassandra-3.11.1
Yes, i'm dosing a single host test
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---- On Mon, 12 Mar 2018 09:24:04 +0330 *Jeff
Jirsa <jji...@gmail.com
<mailto:jji...@gmail.com>>* wrote ----
Would help to know your version. 130
ops/second sounds like a ridiculously low
rate. Are you doing a single host test?
On Sun, Mar 11, 2018 at 10:44 PM, onmstester
onmstester <onmstes...@zoho.com
<mailto:onmstes...@zoho.com>> wrote:
I'm going to benchmark Cassandra's write
throughput on a node with following spec:
* CPU: 20 Cores
* Memory: 128 GB (32 GB as Cassandra heap)
* Disk: 3 seprate disk for OS, data and
commitlog
* Network: 10 Gb (test it with iperf)
* Os: Ubuntu 16
Running Cassandra-stress:
cassandra-stress write n=1000000 -rate
threads=1000 -mode native cql3 -node X.X.X.X
from two node with same spec as above, i
can not get throughput more than 130 Op/s.
The clients are using less than 50% of
CPU, Cassandra node uses:
* 60% of cpu
* 30% of memory
* 30-40% util in iostat of commitlog
* 300 Mb of network bandwidth
I suspect the network, cause no matter how
many clients i run, cassandra always using
less than 300 Mb. I've done all the tuning
mentioned by datastax.
Increasing wmem_max and rmem_max did not
help either.
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