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https://issues.apache.org/jira/browse/OAK-5859?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael Dürig resolved OAK-5859.
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Resolution: Won't Fix
> Analyse and reduce IO amplification by OS
> -----------------------------------------
>
> Key: OAK-5859
> URL: https://issues.apache.org/jira/browse/OAK-5859
> Project: Jackrabbit Oak
> Issue Type: Task
> Components: segment-tar
> Reporter: Michael Dürig
> Priority: Major
> Labels: performance, scalability
>
> Certain operation system settings might result in too much data actually
> being read from disk causing early setting on of thrashing. E.g. transparent
> huge pages or too big read aheads might be contra productive in combination
> with the TarMKs memory mapping model.
> * Determine the ratio of data being read by the TarMK and actual data being
> read from disk. Determine the impact of relevant OS parameters (e.g.
> transparent huge pages) on this ratio.
> * Compare memory mapped mode with file IO mode with an accordingly increased
> segment cache. This would move prediction of what is likely to be read next
> from the OS layer into our segment cache eviction strategy.
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