Date: Sun, 20 May 2012 18:12:01 -0500 From: Alan Cox <alc@rice.edu> To: Marko Zec <zec@fer.hr> Cc: alc@freebsd.org, freebsd-hackers@freebsd.org, freebsd-amd64@freebsd.org Subject: Re: superpages and kmem on amd64 Message-ID: <4FB97A41.70405@rice.edu> In-Reply-To: <201205210048.16877.zec@fer.hr> References: <201205200901.32613.zec@fer.hr> <201205201643.01194.zec@fer.hr> <4FB92B22.5020304@rice.edu> <201205210048.16877.zec@fer.hr>
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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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