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Date: Tue, 12 Feb 2008 07:33:54 -0800
From: mark gross <mgross@...ux.intel.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
Greg KH <greg@...ah.com>
Subject: Re: iova RB tree setup tweak.
On Mon, Feb 11, 2008 at 02:29:46PM -0800, Andrew Morton wrote:
> On Mon, 11 Feb 2008 13:56:51 -0800
> mark gross <mgross@...ux.intel.com> wrote:
>
> > The following patch merges two functions into one allowing for a 3%
> > reduction in overhead in locating, allocating and inserting pages for
> > use in IOMMU operations.
> >
> > Its a bit of a eye-crosser so I welcome any RB-tree / MM experts to take
> > a look. It works by re-using some of the information gathered in the
> > search for the pages to use in setting up the IOTLB's in the insertion
> > of the iova structure into the RB tree.
> >
>
> I guess this is a PCI patch hence I'd be tagging is as
> to-be-merged-via-greg's-pci-tree.
>
> >
> > Singed-off-by: <mgross@...ux.intel.com>
> >
>
> ow, that musta hurt.
Not at first but ever since I posted the patch its been a bit.
>
> >
> > Index: linux-2.6.24-mm1/drivers/pci/iova.c
> > ===================================================================
> > --- linux-2.6.24-mm1.orig/drivers/pci/iova.c 2008-02-07 11:05:44.000000000 -0800
> > +++ linux-2.6.24-mm1/drivers/pci/iova.c 2008-02-07 13:05:03.000000000 -0800
> > @@ -72,20 +72,25 @@
> > return pad_size;
> > }
> >
> > -static int __alloc_iova_range(struct iova_domain *iovad, unsigned long size,
> > - unsigned long limit_pfn, struct iova *new, bool size_aligned)
> > +static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
> > + unsigned long size, unsigned long limit_pfn,
> > + struct iova *new, bool size_aligned)
> > {
> > - struct rb_node *curr = NULL;
> > + struct rb_node *prev, *curr = NULL;
> > unsigned long flags;
> > unsigned long saved_pfn;
> > unsigned int pad_size = 0;
> >
> > /* Walk the tree backwards */
> > spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
> > saved_pfn = limit_pfn;
> > curr = __get_cached_rbnode(iovad, &limit_pfn);
> > + prev = curr;
> > while (curr) {
> > struct iova *curr_iova = container_of(curr, struct iova, node);
> > +
> > if (limit_pfn < curr_iova->pfn_lo)
> > goto move_left;
> > else if (limit_pfn < curr_iova->pfn_hi)
> > @@ -99,6 +104,7 @@
>
> For some reason patch(1) claims that the patch is corrupted at this line.
>
My bad. Try the following:
--mgross
Signed-off-by : <mgross@...ux.intel.com> fa-la-la
Index: linux-2.6.24-mm1/drivers/pci/iova.c
===================================================================
--- linux-2.6.24-mm1.orig/drivers/pci/iova.c 2008-02-07 11:05:44.000000000 -0800
+++ linux-2.6.24-mm1/drivers/pci/iova.c 2008-02-12 07:12:47.000000000 -0800
@@ -72,10 +72,11 @@
return pad_size;
}
-static int __alloc_iova_range(struct iova_domain *iovad, unsigned long size,
- unsigned long limit_pfn, struct iova *new, bool size_aligned)
+static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
+ unsigned long size, unsigned long limit_pfn,
+ struct iova *new, bool size_aligned)
{
- struct rb_node *curr = NULL;
+ struct rb_node *prev, *curr = NULL;
unsigned long flags;
unsigned long saved_pfn;
unsigned int pad_size = 0;
@@ -84,8 +85,10 @@
spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
saved_pfn = limit_pfn;
curr = __get_cached_rbnode(iovad, &limit_pfn);
+ prev = curr;
while (curr) {
struct iova *curr_iova = container_of(curr, struct iova, node);
+
if (limit_pfn < curr_iova->pfn_lo)
goto move_left;
else if (limit_pfn < curr_iova->pfn_hi)
@@ -99,6 +102,7 @@
adjust_limit_pfn:
limit_pfn = curr_iova->pfn_lo - 1;
move_left:
+ prev = curr;
curr = rb_prev(curr);
}
@@ -115,7 +119,33 @@
new->pfn_lo = limit_pfn - (size + pad_size) + 1;
new->pfn_hi = new->pfn_lo + size - 1;
+ /* Insert the new_iova into domain rbtree by holding writer lock */
+ /* Add new node and rebalance tree. */
+ {
+ struct rb_node **entry = &((prev)), *parent = NULL;
+ /* Figure out where to put new node */
+ while (*entry) {
+ struct iova *this = container_of(*entry,
+ struct iova, node);
+ parent = *entry;
+
+ if (new->pfn_lo < this->pfn_lo)
+ entry = &((*entry)->rb_left);
+ else if (new->pfn_lo > this->pfn_lo)
+ entry = &((*entry)->rb_right);
+ else
+ BUG(); /* this should not happen */
+ }
+
+ /* Add new node and rebalance tree. */
+ rb_link_node(&new->node, parent, entry);
+ rb_insert_color(&new->node, &iovad->rbroot);
+ }
+ __cached_rbnode_insert_update(iovad, saved_pfn, new);
+
spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
+
+
return 0;
}
@@ -171,23 +201,15 @@
size = __roundup_pow_of_two(size);
spin_lock_irqsave(&iovad->iova_alloc_lock, flags);
- ret = __alloc_iova_range(iovad, size, limit_pfn, new_iova,
- size_aligned);
+ ret = __alloc_and_insert_iova_range(iovad, size, limit_pfn,
+ new_iova, size_aligned);
+ spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags);
if (ret) {
- spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags);
free_iova_mem(new_iova);
return NULL;
}
- /* Insert the new_iova into domain rbtree by holding writer lock */
- spin_lock(&iovad->iova_rbtree_lock);
- iova_insert_rbtree(&iovad->rbroot, new_iova);
- __cached_rbnode_insert_update(iovad, limit_pfn, new_iova);
- spin_unlock(&iovad->iova_rbtree_lock);
-
- spin_unlock_irqrestore(&iovad->iova_alloc_lock, flags);
-
return new_iova;
}
--
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