Configuring Glasgow Haskell Compiler Runtime System Options

Depending on hardware specifications, in some implementations of Cardano Node configuring runtime system (RTS) options available for the Glasgow Haskell Compiler (GHC) may improve performance and/or stability.

The RTS offers many options for controlling behaviour. For example, depending on your system specifications and the Cardano Node version, your block-producing node sometimes may miss slot leader checks, as reported using the gLiveView dashboard. Using custom RTS options, you may seek to reduce significantly the number of slot leader checks that your block producer misses, for example due to time spent in garbage collection (GC).

For suggestions on reducing the number of missed slot leader checks, see the topic Reducing Missed Slot Leader Checks.

To display the default RTS options for Cardano Node:

• In a terminal window, type:

cardano-node +RTS --info

In the results, the value of the Flag -with-rtsopts key displays the default RTS options. For example:

-T -I0 -A16m -N2 --disable-delayed-os-memory-return

For details on available RTS options and setting RTS options using the command line, in the GHC User's Guide see the sections RTS Options for SMP Parallelism on page 136 and Running a Compiled Program on page 172.

For example, to produce runtime system statistics for each garbage collection in addition to using default RTS options, include the following RTS option in your cardano-node run command where <FileName> is the name of the file in the current folder where you want to output statistics and <Options> is the list of options that you use when running your node:

/usr/local/bin/cardano-node run +RTS -S<FileName> -RTS <Options>

If you are not satisfied with the performance or stability of an instance of Cardano Node, then subjectively you may notice improvement when adding custom RTS options such as:

+RTS -N -qg -qb -RTS

+RTS -I0.3 -Iw600 -F1.5 -H2500M -RTS

+RTS -M12g -N -RTS

Using similar syntax, you can configure custom RTS options when running the Cardano Command Line Interface (CLI).

To display the default RTS options for Cardano CLI:

• In a terminal window, type:

cardano-cli +RTS --info

If you identify different RTS options that noticably improve the performance or stability of your Cardano Node instance, then consider contributing the RTS options to Coin Cashew so that other stake pools may also benefit.