Benedict created CASSANDRA-7061:
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Summary: High accuracy, low overhead local read/write tracing
Key: CASSANDRA-7061
URL: https://issues.apache.org/jira/browse/CASSANDRA-7061
Project: Cassandra
Issue Type: Improvement
Components: Core
Reporter: Benedict
Assignee: Benedict
Fix For: 3.0
External profilers are pretty inadequate for getting accurate information at
the granularity we're working at: tracing is too high overhead, so measures
something completely different, and sampling suffers from bias of attribution
due to the way the stack traces are retrieved. Hyperthreading can make this
even worse.
I propose to introduce an extremely low overhead tracing feature that must be
enabled with a system property that will trace operations within the node only,
so that we can perform various accurate low level analyses of performance. This
information will include threading info, so that we can trace hand off delays
and actual active time spent processing an operation. With the property
disabled there will be no increased burden of tracing, however I hope to keep
the total trace burden to less than one microsecond, and any single trace
command to a few tens of nanos.
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