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https://issues.apache.org/jira/browse/FLINK-8117?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Gabor Gevay updated FLINK-8117:
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Description:
{{RoundRobinChannelSelector}}, {{RebalancePartitioner}}, and
{{RescalePartitioner}} use a modulo operation to wrap around when the current
channel counter reaches the number of channels. Using an {{if}} would have
better performance.
A division with 32 bit operands is ~25 cycles on modern Intel CPUs \[1\], but
the {{if}} will be only 1-2 cycles on average, since the branch predictor can
most of the time predict the condition to be false.
\[1\] http://www.agner.org/optimize/instruction_tables.pdf
was:
Both {{RoundRobinChannelSelector}} and {{RebalancePartitioner}} use a modulo
operation to wrap around when the current channel counter reaches the number of
channels. Using an {{if}} would have better performance.
A division with 32 bit operands is ~25 cycles on modern Intel CPUs \[1\], but
the {{if}} will be only 1-2 cycles on average, since the branch predictor can
most of the time predict the condition to be false.
\[1\] http://www.agner.org/optimize/instruction_tables.pdf
> Eliminate modulo operation from RoundRobinChannelSelector and
> RebalancePartitioner
> ----------------------------------------------------------------------------------
>
> Key: FLINK-8117
> URL: https://issues.apache.org/jira/browse/FLINK-8117
> Project: Flink
> Issue Type: Improvement
> Components: Local Runtime, Streaming
> Reporter: Gabor Gevay
> Assignee: Gabor Gevay
> Priority: Minor
> Labels: performance
> Fix For: 1.5.0
>
>
> {{RoundRobinChannelSelector}}, {{RebalancePartitioner}}, and
> {{RescalePartitioner}} use a modulo operation to wrap around when the current
> channel counter reaches the number of channels. Using an {{if}} would have
> better performance.
> A division with 32 bit operands is ~25 cycles on modern Intel CPUs \[1\], but
> the {{if}} will be only 1-2 cycles on average, since the branch predictor can
> most of the time predict the condition to be false.
> \[1\] http://www.agner.org/optimize/instruction_tables.pdf
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