== Latency tuning guidelines ==

Many of our tutorials and applications depend on reliabile, low latency processing. 

This is a rough checklist of steps for creating an image (e.g. baseline_1804_lowlatency) that has minimized deterministic latency.

factors affecting this:
* maximum stable processor clock speed
  * we cannot depend on boost states (intel turbo boost), as they can't be maintained under all load conditions, or for many cores.
  * it is possible to fix a small number of cores to a high boost by disabling others, but this usually requires bios support
* number of cpus
  * systems with multiple cpus can introduce latency with communication between them. Single cpu systems are much simpler to optimize
  * NUMA issues: with multiple cpus, you must pay close attention to which memory is allocated to which cpu, as well as where pcie devices are attached.


1. Choosing node to use:
  * from above, pick a node with a single cpu, and the maximum clock available
1. install a low latency kernel
 * {{{ apt install linux-lowlatency-hwe-18.04 linux-tools-lowlatency-hwe-18.04}}}
1. usage of tuned-adm
  * tuned is a perfomance optimization project that wraps many configuration methods
  * {{{ apt install tuned }}}


== Monitoring tools ==

* htop
* i7z
* hwloc (to show pci and numa layout)