CONFIG_CACHE_WRITETHROUGH is not available for thedefaultarchitecture x86.
Result is shown for architecture sh

Write-through

configname: CONFIG_CACHE_WRITETHROUGH

Cache mode
└─>Write-through
In linux kernel since version 2.6.24 (release Date: 2008-01-24)  
Selecting this option will configure the caches in write-through
mode, as opposed to the default write-back configuration.

Since there's sill some aliasing issues on SH-4, this option will
unfortunately still require the majority of flushing functions to
be implemented to deal with aliasing.

If unsure, say N.