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https://issues.apache.org/jira/browse/DISPATCH-1372?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16875408#comment-16875408
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ASF GitHub Bot commented on DISPATCH-1372:
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franz1981 commented on issue #525: DISPATCH-1372 alloc_pool intrusive linked
list can be replaced by a linked stack
URL: https://github.com/apache/qpid-dispatch/pull/525#issuecomment-506878556
@kgiusti Do you know if it was the version with the first or the last
commit? The second commit has introduced a memcpy and has been written super in
hurry, maybe the first commit ie a946341f711a1d22c144299d846c6d9c804538e4
doesn't have that bug...
I've run long tests (2 hour each) with several clients (4) on both the
commits with/without debug mode and I haven't hit this same failure :(
I will try to do the same with 2 routers to se if I'm able to hit it...
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> alloc_pool intrusive linked list can be replaced by a linked stack
> ------------------------------------------------------------------
>
> Key: DISPATCH-1372
> URL: https://issues.apache.org/jira/browse/DISPATCH-1372
> Project: Qpid Dispatch
> Issue Type: Improvement
> Components: Routing Engine
> Affects Versions: 1.8.0
> Reporter: Francesco Nigro
> Priority: Major
> Attachments: DOOM-3-BFG-Technical-Note.pdf,
> image-2019-06-21-11-08-17-015.png, image-2019-06-21-11-09-02-228.png,
> linked_list_misses.svg, stack_list_misses.svg
>
>
> alloc_pool is currently using a intrusive linked list approach to reduce the
> need of external data structures to hold data, saving expensive pointer
> chasing, but on modern architectures the data dependency between a current
> node and next/prev prevent the CPU prefetcher to stream nodes speculatively.
> There are different approaches that could benefit of prefetcing, but need to
> decouple the data stored from its container eg a linked stack.
> A linked stack is composed by doubly-linked chunks (allocated lazily) that
> make possible for the CPU to prefetch next/prev pointers given that those are
> already contained in the current chunk (if any).
> Although it seems counter-intuitive (given that introduce 1 more hop to reach
> the data), such data-structure is much more cache-friendly on modern
> architectures: I will attach some cache misses analysis to show it.
>
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