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https://issues.apache.org/jira/browse/DISPATCH-2000?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ganesh Murthy updated DISPATCH-2000:
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Priority: Major (was: Critical)
> Consider increasing default internal buffer size
> ------------------------------------------------
>
> Key: DISPATCH-2000
> URL: https://issues.apache.org/jira/browse/DISPATCH-2000
> Project: Qpid Dispatch
> Issue Type: Improvement
> Components: Router Node
> Affects Versions: 1.15.0
> Reporter: Charles E. Rolke
> Assignee: Ganesh Murthy
> Priority: Major
> Fix For: 1.18.0
>
>
> Tests with the TCP adaptor and a 4k-byte buffer size show _significant
> throughput increases_ with _otherwise minimal code changes_. For this
> discussion, assume that the new buffer size will be 4k bytes.
> Note: This discussion nearly parallels the discussion of increasing hard
> drive sector size to 4K. See [Transition to Advanced Format 4K Sector Hard
> Drives
> |[https://www.seagate.com/tech-insights/advanced-format-4k-sector-hard-drives-master-ti/].]
> The pros and cons of increasing the size for disk drives and for
> qpid-dispatch are pretty much the same.
> Dispatch has never had anything but 512-byte internal buffers. This lends a
> lot of weight for keeping the current setting. However, from day one the self
> tests exercise various buffer sizes from 1-byte to 10000-bytes and the tests
> have worked fine. This is a positive indication that physically the buffer
> functions and buffer management proper would work with any buffer size.
> Logically there are some other issues. These must be understood and
> considered before moving forward with any change.
> * Expect total memory usage to go up due to unused buffer space with small
> messages
> * Expect total memory usage to go down due to more efficient buffer use with
> large messages
> * Policy implements Q2 throttling with a buffer count limit. If that limit
> is not adjusted then flow control will not take effect until 8x as much AMQP
> session data has been buffered.
> Adjusting the buffer size from 512 to 4096 must happen either at compile time
> or at run time very early, before qd_router_setup_late() is called, when
> buffers start being created and buffer size cannot be changed any more. A
> pull request is in the works that adds a --4k-buffer switch to the command
> line to simplify testing with the larger buffer size.
> I expect that going to 4K buffers will have a performance improvement
> certainly for the TCP adaptor but also for the other protocol adaptors and
> for AMQP as well.
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