Re: kmem-pool-uvm

[Mindaugas Rasiukevicius <rmind%netbsd.org@localhost>]

yamt%mwd.biglobe.ne.jp@localhost (YAMAMOTO Takashi) wrote:
> >> let me explain some background. currently there are a number of
> >> kernel_map related problems:
> >>
> >> A-1. vm_map_entry is unnecessarily large for KVA allocation purpose.
> >>
> >> A-2. kernel-map-entry-merging is there to solve A-1. but it introduced
> >> the allocate-for-free problem. ie. to free memory, you might need to
> >> split map-entries thus allocate some memory.
> >>
> >> A-3. to solve A-2, there is map-entry-reservation mechanism. it's
> > complicated and broken.
> >>
> <...>
> 
> i agree that having two allocator for KVA is bad.
> my idea is having just one. (kernel_va_arena)
> no allocation would be made by vm_map_entries for kernel_map.
> kernel_map is kept merely for fault handling.
> 
> essentially kva allocation would be:
> 
>       va = vmem_alloc(kernel_va_arena, ...);
>       if (pageable)
>               create kernel_map entry for the va
>       else
>               ...
>       return va;

I like this a lot.  Seems an overall win.

-- 
Mindaugas