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Jason Rahm

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Lightboard Lessons: CPU Hyper-Threads and TMM

In this episode of Lightboard Lessons, Jason details how BIG-IP’s Traffic Management Microkernel (TMM) utilizes Intel’s Hyper-Threading Technology (on applicable platforms) and the impacts depending on the version of TMOS. In versions before 11.5, each hyper-thread has a separate TMM running. In versions 11.5 and later, TMM and control plane tasks are assigned to separate hyper-threads by default, a behavior we call HTSplit. This behavior is controlled by the scheduler.splitplanes.ltm database key.


  • K15003: Data plane and control plane tasks use separate logical cores when the BIG-IP system CPU uses Hyper-Threading Technology
  • K23505424: Overview of the HTSplit feature
  • K14358: Overview of Clustered Multiprocessing (11.3.0 and later)
  • K10095: Error Message: Clock advanced by ticks
  • K16469: Certain BIG-IP ASM control plane processes are now pinned to the highest-numbered logical CPU core

Read the original blog entry...

More Stories By Jason Rahm

Experienced predominantly in the networking realm over the last dozen or so years, Jason is expanding his horizons towards systems management and even trying his hand at python.

Jason assists in the maintenance duties for, contributes frequently in the forums, and writes weekly on some cool geekery in the F5 product lines. When not working, Jason enjoys spending time with his beautiful wife Michelle and his four children. He is active and volunteers network administration duties at his church and if there are any remaining minutes in the week, he enjoys Wii & XBOX, tennis, racquetball, softball, etc. He does not enjoy running, but does (scratch that, thinks about doing) it anyway to recover his youthful appearance.