Re: [kvm-devel] [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges

2008-01-31 Thread Andrea Arcangeli
On Wed, Jan 30, 2008 at 06:51:26PM -0800, Christoph Lameter wrote: > True. hlist_del_init ok? That would allow to check the driver that the > mmu_notifier is already linked in using !hlist_unhashed(). Driver then > needs to properly initialize the mmu_notifier list with INIT_HLIST_NODE(). A driv

Re: [kvm-devel] [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges

2008-01-31 Thread Andrea Arcangeli
On Wed, Jan 30, 2008 at 05:46:21PM -0800, Christoph Lameter wrote: > Well the GRU uses follow_page() instead of get_user_pages. Performance is > a major issue for the GRU. GRU is a external TLB, we have to allocate RAM instead but we do it through the regular userland paging mechanism. Performan

Re: [kvm-devel] [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges

2008-01-30 Thread Christoph Lameter
On Thu, 31 Jan 2008, Andrea Arcangeli wrote: > On Wed, Jan 30, 2008 at 06:08:14PM -0800, Christoph Lameter wrote: > > hlist_for_each_entry_safe_rcu(mn, n, t, > > > > &mm->mmu_notifier.head, hlist) { > >

Re: [kvm-devel] [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges

2008-01-30 Thread Andrea Arcangeli
On Wed, Jan 30, 2008 at 06:08:14PM -0800, Christoph Lameter wrote: > hlist_for_each_entry_safe_rcu(mn, n, t, > &mm->mmu_notifier.head, hlist) { > hlist_del_rcu(&mn->hlist);

Re: [kvm-devel] [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges

2008-01-30 Thread Christoph Lameter
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

Re: [kvm-devel] [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges

2008-01-30 Thread Robin Holt
> 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 acco

Re: [kvm-devel] [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges

2008-01-30 Thread Christoph Lameter
Patch to 1. Remove sync on notifier_release. Must be called when only a single process remain. 2. Add invalidate_range_start/end. This should allow safe removal of ranges of external ptes without having to resort to a callback for every individual page. This must be able to nest so t

Re: [kvm-devel] [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges

2008-01-30 Thread Christoph Lameter
On Thu, 31 Jan 2008, Andrea Arcangeli wrote: > On Wed, Jan 30, 2008 at 04:01:31PM -0800, Christoph Lameter wrote: > > How we offload that? Before the scan of the rmaps we do not have the > > mmstruct. So we'd need another notifier_rmap_callback. > > My assumption is that that "int lock" exists j

Re: [kvm-devel] [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges

2008-01-30 Thread Andrea Arcangeli
On Wed, Jan 30, 2008 at 04:01:31PM -0800, Christoph Lameter wrote: > How we offload that? Before the scan of the rmaps we do not have the > mmstruct. So we'd need another notifier_rmap_callback. My assumption is that that "int lock" exists just because unmap_mapping_range_vma exists. If I'm right