On Sunday 20 May 2012 09:25:59 Alan Cox wrote: > On Sun, May 20, 2012 at 2:01 AM, Marko Zec <z...@fer.hr> wrote: > > Hi all, > > > > I'm playing with an algorithm which makes use of large contiguous blocks > > of kernel memory (ranging from 1M to 1G in size), so it would be nice if > > those could be somehow forcibly mapped to superpages. I was hoping that > > the VM system would automagically map (merge) contiguous 4k pages to > > superpages, but > > apparently it doesn't: > > > > vm.pmap.pdpe.demotions: 2 > > vm.pmap.pde.promotions: 543 > > vm.pmap.pde.p_failures: 266253 > > vm.pmap.pde.mappings: 0 > > vm.pmap.pde.demotions: 31 > > No, your conclusion is incorrect. These counts show that 543 superpage > mappings were created by promotion.
OK, that sounds promising. Does "created by promotion" count reflect historic / cumulative stats, or is vm.pmap.pde.promotions the actual number of superpages active? Or should we subtract vm.pmap.pde.demotions from it to get the current value? 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? 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)? Thanks, Marko _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
