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host_options

"host_options" defines specific options of ACE (DIT) translator and code-generator in form of switches.

The following switches are available to user:

. Those options affect Charon perfromance

Default settings are set to optimize perfromance for most geust OS (VMS and Tru64) usage profiles. However there are some profiles (for example OpenVMS compilation tasks) where the default settings do not provide optimal perfromance.

The following switches are available to user:

1. --fixed-variant=[X]

The value X is in range -1..1can be one of three options: [-1, 0, 1]. This value defines the desired translation variant. Set -1 for dynamic (default) or [ 0 ..or 1 ] for the fixed number implemented by the translator.

2. --x64-optimize 

This switch enables optimizations (default).

3. optimize or --x64-nooptimize 

This switch disables optimizationsenables translartion optimizations (the default is to optimize).

Example:

Despite the fact that CHARON is already optimized for wide range of the guest OS tasks, there may be some situations (for example OpenVMS compilation tasks) when performance degradation may reach about 50% of the version 4.8. In this case the "host_options" switches must be set to the values shown in the example above. Note that in this case the parameter "num_translators" must be set to the number of I/O CPUs dedicated to CHARON (see the "n_of_io_cpus" parameter). Also note that changing parameter "cache_size" can be an alternative solution too (see the section below).

 Do not change this parameter without clear understanding the purpose.