Subject: Re: Looking for advice on using pageable memory
To: Julio M.Merino Vidal <firstname.lastname@example.org>
From: Jason Thorpe <email@example.com>
Date: 11/13/2006 09:46:27
On Nov 13, 2006, at 4:26 AM, Julio M. Merino Vidal wrote:
> 2) Then I tried to tweak the uvm_km_alloc_poolpage and other
> related functions (their *_cached and *free* counterparts) to
> pageable kernel memory by using the UVM_KMF_PAGEABLE flag
> (instead of the UVM_KMF_WIRED currently used). Similarly I changed
> usages of pmap_kenter_va for pmap_enter which allows me to _not_
> pass the wired flag.
> This worked (the system didn't crash, that is) but the system could
> not send them to swap at all. It also reached a limit were it could
> not allocate more pages (even when there was plenty of free swap
> space), so it started thrashing as crazy.
> Does it have any effect to set a page UVM_KMF_PAGEABLE in the
> main kernel map? It doesn't seem so...
kernel_map is already pageable:
uvm_map_setup_kernel(&kernel_map_store, base, end,
The right thing for you to do is to simply define your own pool page
allocator for your tmpfs pools, and use uvm_km_alloc(kernel_map, ...,
UVM_KMF_PAGEABLE) within that allocator to allocate the pages.