DragonFly BSD
DragonFly kernel List (threaded) for 2010-10
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Re: 'Change the vm_map lookup algorithm'

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Sun, 3 Oct 2010 16:09:13 -0700 (PDT)

    #1 on my list of things that can make the system faster now would be
    how to MP-lock the VM system.

    The problem the VM system has is that there is a billion different ways
    to drill down into it.  Via the filesystem buffer cache, via VM objects,
    via the pmap (pmap->pte->vm_page), via pv_entry's in the pmap,
    via VM pages, via the vm_map... those are the main ones.

    So what we need to do is to come up with a way to MP lock the VM system
    that is more fine-grained than our current vm_token but which allows
    the above various methods to be implemented without having to acquire
    tons of different locks on the way down.

    This will bear a strong relationship to whatever indexing mechanic is
    chosen for vm_map's, and perhaps also vm_object's which currently use
    a RB tree as well (vm_object->rb_memq and vm_object->swblock_root).

					Matthew Dillon 

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