Messages in this thread |  | | | Date | Wed, 30 Jan 2008 18:37:26 -0800 (PST) | | From | Christoph Lameter <> | | Subject | Re: [kvm-devel] [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges |
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On Wed, 30 Jan 2008, Robin Holt wrote:
> > Well the GRU uses follow_page() instead of get_user_pages. Performance is > > a major issue for the GRU. > > Worse, the GRU takes its TLB faults from within an interrupt so we > use follow_page to prevent going to sleep. That said, I think we > could probably use follow_page() with FOLL_GET set to accomplish the > requirements of mmu_notifier invalidate_range call. Doesn't look too > promising for hugetlb pages.
There may be no need to with the range_start/end scheme. The driver can have its own lock to make follow page secure. The lock needs to serialize the follow_page handler and the range_start/end calls as well as the invalidate_page callouts. I think that avoids the need for get_user_pages().
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