tech-kern archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: pool_cache_get behavior

haad <> wrote:
> ad@
> KM_NOSLEEP... probably due to that implying UVM_MAP_TRYLOCK
> The issue is that parts of kernel_map are pageable. Paging can take a
> long time, and the map can be held locked while paging.
> Therefore when we do a NOSLEEP allocation from kernel_map, it's also
> implicitly a TRYLOCK one because we can't wait to lock the map.

FYI: Related problem is described in PR/38270.  In this case, I guess
kmem_map, which is used by pool(9) and is VM_MAP_INTRSAFE, could avoid
trylock because map is locked by a spin-mutex (at IPL_VM).

It is not the case for kernel_map (at IPL_DEFAULT), used by kmem(9).
There is yamt-kmem branch which has been revamping this.  yamt?


Home | Main Index | Thread Index | Old Index