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  1. Couchbase Server
  2. MB-49501

Indexer cpu throttle cuts query throughput by 47%

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    • Untriaged
    • Centos 64-bit
    • 1
    • Unknown

    Description

      There was a previous issue opened https://issues.couchbase.com/browse/MB-49301 but resolved as not a bug. Maybe more details of the CPU throttle algorithm could help understand the result better and how its intended to work. When I set the throttle level to 0.95, query throughput gets reduced by 40%. The performance test pushes indexer cpu normally close to 100%. If the throttle level is set to 0.95 why does cpu usage get throttled down to 60% instead of right below 95%. It seems there is a lot of wasted cpu cycles here.

      Comparing these two test on 7.1.0-1650:

      http://showfast.sc.couchbase.com/#/timeline/Linux/n1ql/Q5_Q7/all

      Avg. Query Throughput (queries/sec), CI6, Group By Query (1K matches), MOI, not_bounded, s=1 c=1 i=1

      http://perf.jenkins.couchbase.com/job/iris-multi-client/12973/ - 15280

      Avg. Query Throughput (queries/sec), CI6, Group By Query (1K matches), MOI, not_bounded, Indexer CPU Throttle 0.95, s=1 c=1 i=1

      http://perf.jenkins.couchbase.com/job/iris-multi-client/13027/  - 7651

      graph comparison: http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=iris_710-1650_access_0436&snapshot=iris_710-1650_access_afdf

      Indexer cpu drops from 4800% to 3000%

      http://cbmonitor.sc.couchbase.com/reports/html/?snapshot=iris_710-1650_access_0436&snapshot=iris_710-1650_access_afdf#0103718d11a8aa31d5c328c63302ff1d

       

      Logs from throttle run (.45 is the index node):

      https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-iris-multi-client-13027/172.23.100.45.zip

      https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-iris-multi-client-13027/172.23.100.55.zip

      https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-iris-multi-client-13027/172.23.100.70.zip

      https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-iris-multi-client-13027/172.23.100.71.zip

      https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-iris-multi-client-13027/172.23.100.72.zip

      https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-iris-multi-client-13027/172.23.100.73.zip

      https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-iris-multi-client-13027/172.23.100.9.zip

       

      Is this really the intended behaviour? This seems like it could have negative side effects when upgrading a cluster if this is the default setting.

       

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              korrigan.clark Korrigan Clark
              korrigan.clark Korrigan Clark
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                Updated:
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