RFE ARC readonly mode for some processes #18404
Description
Describe the feature you would like to see added to OpenZFS
Allow some processes to use the ARC without changing it.
How will this feature improve OpenZFS?
This would allow some administrative tools like duc to walk through all of the metadata in a pool without triggering arc_evict and arc_prune, with resulting performance hits for primary production applications.
Additional context
It might also be useful for some background tasks to be able to access a large amount of data without perturbing the cache.