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[[!tag open_issue_viengoos]]

The current hash function in libhurd-ihash results in a lot of
collisions when the hash table is 80% full.  To overcome this, we keep
hash tables at most 30% full.  This represents a fair amount of
overhead.  Find a better algorithm.  There can either be one that is
appropriate in the general case or one that works well in a relevant,
specific case, e.g., viengoos/object.c uses a hash to find the object
corresponding to a frame, which is keyed on its physical address.