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dnsdist: Cache sharding, recvmmsg and CPU pinning support #5576

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merged 10 commits into from Sep 27, 2017

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rgacogne commented Aug 2, 2017

Short description

  • Optionally divide the packet cache into several shards, each protected by its own lock, to reduce lock contention
  • Add support for recvmmsg(), sendmmsg() and accept4() when available to reduce the number of system calls
  • Add support for pinning UDP listener threads to specific CPU cores
  • Several small optimizations including not using errno when we don't have to and not generating a UUID if we don't need it

A large part of the PR is just moving code around to be able to process queries one-by-one (with recvmsg(), the default) or in batch (with recvmmsg()).

Checklist

I have:

  • read the CONTRIBUTING.md document
  • compiled and tested this code
  • included documentation (including possible behaviour changes)
  • documented the code
  • added or modified regression test(s)
  • added or modified unit test(s)

@rgacogne rgacogne added this to the dnsdist-1.2.0 milestone Aug 2, 2017

@rgacogne rgacogne modified the milestones: dnsdist-1.3.0, dnsdist-1.2.0 Aug 3, 2017

@rgacogne rgacogne force-pushed the rgacogne:dnsdist-sharded-mmsg branch from d28196c to 2d67e8c Aug 10, 2017

@rgacogne rgacogne force-pushed the rgacogne:dnsdist-sharded-mmsg branch from 2d67e8c to ab1b354 Aug 22, 2017

rgacogne added some commits Jul 11, 2017

dnsdist: Add support for sharding the packet cache
Also make the cache insert lock optionally deferrable.
Lock: Don't access and even less write to errno unless we have to
POSIX.1c made `errno` a thread-local, meaning its performance is
far worse than the one of a local variable.
dnsdist: Add console completion and docs for the new additions:
* CPU pinning
* Cache sharding / deferred locking
* `recvmmsg()` use

@rgacogne rgacogne force-pushed the rgacogne:dnsdist-sharded-mmsg branch from ab1b354 to 4bc167b Sep 5, 2017

@rgacogne rgacogne referenced this pull request Sep 15, 2017

Open

calidns: macOS stubs for send/recvmmsg #5695

2 of 6 tasks complete

@ahupowerdns ahupowerdns merged commit 8b3f9b4 into PowerDNS:master Sep 27, 2017

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continuous-integration/travis-ci/pr The Travis CI build passed
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@rgacogne rgacogne deleted the rgacogne:dnsdist-sharded-mmsg branch Sep 28, 2017

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