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https://issues.apache.org/jira/browse/DISPATCH-2000?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17332741#comment-17332741
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ASF GitHub Bot commented on DISPATCH-2000:
------------------------------------------

ChugR commented on a change in pull request #1073:
URL: https://github.com/apache/qpid-dispatch/pull/1073#discussion_r620645224



##########
File path: tests/run_unit_tests.c
##########
@@ -45,7 +45,7 @@ int main(int argc, char** argv)
     int result = 0;
 
     // Call qd_dispatch() first initialize allocator used by other tests.
-    qd_dispatch_t *qd = qd_dispatch(0, false);
+    qd_dispatch_t *qd = qd_dispatch(0, false, false);

Review comment:
       This PR runs tests with 512-byte buffers only.




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> 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
>            Priority: Major
>
> 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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