Re: first gap in the map

> With current implemention, the only real entries are managed in
> rbtree, and thus the gap after those entries can be searched by rbtree
> walk, right?  So, the gap between map start and the first entry needs
> to be check specially.  The code after /* Check slot before any entry
> */ is the special check (it is necceary for kernel or its sub map).
> 
> But for topdown case, the entry there isn't the first entry usually.
> And since it should be the last resort in topdown case, the test
> should be done after tree walk failed to find space.
>
> But currently `tree walk failed' doesn't mean there was really no
> space in the tree (since the walk doesn't test all candidates).  So,
> fixing this would be a bit hard (possibilly, we want to put the first
> gap in the tree also).

i got your point.  thanks for explanation.

> Also, uvm_rb_space() doesn't need to handle the entry->next ==
> &map->header case specially.  return (entry->next->strart -
> entry->end); is enough.

yea, i'm wondering if 'ownspace' is worth to cache..

YAMAMOTO Takashi