On 05/20/2012 17:48, Marko Zec wrote:
On Sunday 20 May 2012 19:34:26 Alan Cox wrote:
...
In any case, I wish to be certain that a particular kmem virtual address
range is mapped to superpages - how can I enforce that at malloc time,
and / or find out later if I really got my kmem mapped to superpages?
Perhaps vm_map_lookup() could provide more info, but I'm wondering if
someone already wrote a wrapper function for that, which takes only the
base virtual address as a single argument?
Try using pmap_mincore() to verify that the mappings are superpages.
flags = pmap_mincore(vmspace_pmap(curthread->td_proc->p_vmspace),
(vm_offset_t) addr));
OK, that works, and now I know my kmem chunk is on a superpage, horray!!!
Thanks!
BTW, apparently malloc(size, M_TEMP, M_NOWAIT) requests fail for size>
1G, even at boot time. Any ideas how to circumvent that (8.3-STABLE,
amd64, 4G physical RAM)?
I suspect that you need to increase the size of your kmem map.
Huh any hints how should I achieve that? In desperation I placed
vm.kmem_size=8G
in /boot/loader.conf and got this:
vm.kmem_map_free: 8123924480
vm.kmem_map_size: 8364032
vm.kmem_size_scale: 1
vm.kmem_size_max: 329853485875
vm.kmem_size_min: 0
vm.kmem_size: 8132288512
but malloc(2G) still fails...
Here is at least one reason why it fails:
void *
uma_large_malloc(int size, int wait)
Note the type of "size". Can you malloc 1GB?
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