This iova tree function allows it to look for a hole in allocated
regions and return a totally new translation for a given translated
address.
It's usage is mainly to allow devices to access qemu address space,
remapping guest's one into a new iova space where qemu can add chunks of
addresses.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
---
include/qemu/iova-tree.h | 18 ++++++
util/iova-tree.c | 133 +++++++++++++++++++++++++++++++++++++++
2 files changed, 151 insertions(+)
diff --git a/include/qemu/iova-tree.h b/include/qemu/iova-tree.h
index 8249edd764..a623136cd8 100644
--- a/include/qemu/iova-tree.h
+++ b/include/qemu/iova-tree.h
@@ -29,6 +29,7 @@
#define IOVA_OK (0)
#define IOVA_ERR_INVALID (-1) /* Invalid parameters */
#define IOVA_ERR_OVERLAP (-2) /* IOVA range overlapped */
+#define IOVA_ERR_NOMEM (-3) /* Cannot allocate */
typedef struct IOVATree IOVATree;
typedef struct DMAMap {
@@ -119,6 +120,23 @@ const DMAMap *iova_tree_find_address(const IOVATree *tree, hwaddr iova);
*/
void iova_tree_foreach(IOVATree *tree, iova_tree_iterator iterator);
+/**
+ * iova_tree_alloc:
+ *
+ * @tree: the iova tree to allocate from
+ * @map: the new map (as translated addr & size) to allocate in the iova region
+ * @iova_begin: the minimum address of the allocation
+ * @iova_end: the maximum addressable direction of the allocation
+ *
+ * Allocates a new region of a given size, between iova_min and iova_max.
+ *
+ * Return: Same as iova_tree_insert, but cannot overlap and can return error if
+ * iova tree is out of free contiguous range. The caller gets the assigned iova
+ * in map->iova.
+ */
+int iova_tree_alloc_map(IOVATree *tree, DMAMap *map, hwaddr iova_begin,
+ hwaddr iova_end);
+
/**
* iova_tree_destroy:
*
diff --git a/util/iova-tree.c b/util/iova-tree.c
index 23ea35b7a4..302b01f1cc 100644
--- a/util/iova-tree.c
+++ b/util/iova-tree.c
@@ -16,6 +16,39 @@ struct IOVATree {
GTree *tree;
};
+/* Args to pass to iova_tree_alloc foreach function. */
+struct IOVATreeAllocArgs {
+ /* Size of the desired allocation */
+ size_t new_size;
+
+ /* The minimum address allowed in the allocation */
+ hwaddr iova_begin;
+
+ /* Map at the left of the hole, can be NULL if "this" is first one */
+ const DMAMap *prev;
+
+ /* Map at the right of the hole, can be NULL if "prev" is the last one */
+ const DMAMap *this;
+
+ /* If found, we fill in the IOVA here */
+ hwaddr iova_result;
+
+ /* Whether have we found a valid IOVA */
+ bool iova_found;
+};
+
+/**
+ * Iterate args to the next hole
+ *
+ * @args The alloc arguments
+ * @next The next mapping in the tree. Can be NULL to signal the last one
+ */
+static void iova_tree_alloc_args_iterate(struct IOVATreeAllocArgs *args,
+ const DMAMap *next) {
+ args->prev = args->this;
+ args->this = next;
+}
+
static int iova_tree_compare(gconstpointer a, gconstpointer b, gpointer data)
{
const DMAMap *m1 = a, *m2 = b;
@@ -107,6 +140,106 @@ int iova_tree_remove(IOVATree *tree, const DMAMap *map)
return IOVA_OK;
}
+/**
+ * Try to find an unallocated IOVA range between prev and this elements.
+ *
+ * @args Arguments to allocation
+ *
+ * Cases:
+ *
+ * (1) !prev, !this: No entries allocated, always succeed
+ *
+ * (2) !prev, this: We're iterating at the 1st element.
+ *
+ * (3) prev, !this: We're iterating at the last element.
+ *
+ * (4) prev, this: this is the most common case, we'll try to find a hole
+ * between "prev" and "this" mapping.
+ *
+ * Note that this function assumes the last valid iova is HWADDR_MAX, but it
+ * searches linearly so it's easy to discard the result if it's not the case.
+ */
+static void iova_tree_alloc_map_in_hole(struct IOVATreeAllocArgs *args)
+{
+ const DMAMap *prev = args->prev, *this = args->this;
+ uint64_t hole_start, hole_last;
+
+ if (this && this->iova + this->size < args->iova_begin) {
+ return;
+ }
+
+ hole_start = MAX(prev ? prev->iova + prev->size + 1 : 0, args->iova_begin);
+ hole_last = this ? this->iova : HWADDR_MAX;
+
+ if (hole_last - hole_start > args->new_size) {
+ args->iova_result = hole_start;
+ args->iova_found = true;
+ }
+}
+
+/**
+ * Foreach dma node in the tree, compare if there is a hole with its previous
+ * node (or minimum iova address allowed) and the node.
+ *
+ * @key Node iterating
+ * @value Node iterating
+ * @pargs Struct to communicate with the outside world
+ *
+ * Return: false to keep iterating, true if needs break.
+ */
+static gboolean iova_tree_alloc_traverse(gpointer key, gpointer value,
+ gpointer pargs)
+{
+ struct IOVATreeAllocArgs *args = pargs;
+ DMAMap *node = value;
+
+ assert(key == value);
+
+ iova_tree_alloc_args_iterate(args, node);
+ iova_tree_alloc_map_in_hole(args);
+ return args->iova_found;
+}
+
+int iova_tree_alloc_map(IOVATree *tree, DMAMap *map, hwaddr iova_begin,
+ hwaddr iova_last)
+{
+ struct IOVATreeAllocArgs args = {
+ .new_size = map->size,
+ .iova_begin = iova_begin,
+ };
+
+ assert(iova_begin < iova_last);
+
+ /*
+ * Find a valid hole for the mapping
+ *
+ * Assuming low iova_begin, so no need to do a binary search to
+ * locate the first node.
+ *
+ * TODO: Replace all this with g_tree_node_first/next/last when available
+ * (from glib since 2.68). To do it with g_tree_foreach complicates the
+ * code a lot.
+ *
+ */
+ g_tree_foreach(tree->tree, iova_tree_alloc_traverse, &args);
+ if (!args.iova_found) {
+ /*
+ * Either tree is empty or the last hole is still not checked.
+ * g_tree_foreach does not compare (last, iova_end] range, so we check
+ * it here.
+ */
+ iova_tree_alloc_args_iterate(&args, NULL);
+ iova_tree_alloc_map_in_hole(&args);
+ }
+
+ if (!args.iova_found || args.iova_result + map->size > iova_last) {
+ return IOVA_ERR_NOMEM;
+ }
+
+ map->iova = args.iova_result;
+ return iova_tree_insert(tree, map);
+}
+
void iova_tree_destroy(IOVATree *tree)
{
g_tree_destroy(tree->tree);
--
2.27.0
在 2022/2/27 下午9:41, Eugenio Pérez 写道:
> This iova tree function allows it to look for a hole in allocated
> regions and return a totally new translation for a given translated
> address.
>
> It's usage is mainly to allow devices to access qemu address space,
> remapping guest's one into a new iova space where qemu can add chunks of
> addresses.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> Reviewed-by: Peter Xu <peterx@redhat.com>
> ---
> include/qemu/iova-tree.h | 18 ++++++
> util/iova-tree.c | 133 +++++++++++++++++++++++++++++++++++++++
> 2 files changed, 151 insertions(+)
>
> diff --git a/include/qemu/iova-tree.h b/include/qemu/iova-tree.h
> index 8249edd764..a623136cd8 100644
> --- a/include/qemu/iova-tree.h
> +++ b/include/qemu/iova-tree.h
> @@ -29,6 +29,7 @@
> #define IOVA_OK (0)
> #define IOVA_ERR_INVALID (-1) /* Invalid parameters */
> #define IOVA_ERR_OVERLAP (-2) /* IOVA range overlapped */
> +#define IOVA_ERR_NOMEM (-3) /* Cannot allocate */
>
> typedef struct IOVATree IOVATree;
> typedef struct DMAMap {
> @@ -119,6 +120,23 @@ const DMAMap *iova_tree_find_address(const IOVATree *tree, hwaddr iova);
> */
> void iova_tree_foreach(IOVATree *tree, iova_tree_iterator iterator);
>
> +/**
> + * iova_tree_alloc:
Should be iova_tree_alloc_map.
> + *
> + * @tree: the iova tree to allocate from
> + * @map: the new map (as translated addr & size) to allocate in the iova region
> + * @iova_begin: the minimum address of the allocation
> + * @iova_end: the maximum addressable direction of the allocation
> + *
> + * Allocates a new region of a given size, between iova_min and iova_max.
> + *
> + * Return: Same as iova_tree_insert, but cannot overlap and can return error if
> + * iova tree is out of free contiguous range. The caller gets the assigned iova
> + * in map->iova.
> + */
> +int iova_tree_alloc_map(IOVATree *tree, DMAMap *map, hwaddr iova_begin,
> + hwaddr iova_end);
> +
> /**
> * iova_tree_destroy:
> *
> diff --git a/util/iova-tree.c b/util/iova-tree.c
> index 23ea35b7a4..302b01f1cc 100644
> --- a/util/iova-tree.c
> +++ b/util/iova-tree.c
> @@ -16,6 +16,39 @@ struct IOVATree {
> GTree *tree;
> };
>
> +/* Args to pass to iova_tree_alloc foreach function. */
> +struct IOVATreeAllocArgs {
> + /* Size of the desired allocation */
> + size_t new_size;
> +
> + /* The minimum address allowed in the allocation */
> + hwaddr iova_begin;
> +
> + /* Map at the left of the hole, can be NULL if "this" is first one */
> + const DMAMap *prev;
> +
> + /* Map at the right of the hole, can be NULL if "prev" is the last one */
> + const DMAMap *this;
> +
> + /* If found, we fill in the IOVA here */
> + hwaddr iova_result;
> +
> + /* Whether have we found a valid IOVA */
> + bool iova_found;
> +};
> +
> +/**
> + * Iterate args to the next hole
> + *
> + * @args The alloc arguments
> + * @next The next mapping in the tree. Can be NULL to signal the last one
> + */
> +static void iova_tree_alloc_args_iterate(struct IOVATreeAllocArgs *args,
> + const DMAMap *next) {
> + args->prev = args->this;
> + args->this = next;
> +}
> +
> static int iova_tree_compare(gconstpointer a, gconstpointer b, gpointer data)
> {
> const DMAMap *m1 = a, *m2 = b;
> @@ -107,6 +140,106 @@ int iova_tree_remove(IOVATree *tree, const DMAMap *map)
> return IOVA_OK;
> }
>
> +/**
> + * Try to find an unallocated IOVA range between prev and this elements.
> + *
> + * @args Arguments to allocation
> + *
> + * Cases:
> + *
> + * (1) !prev, !this: No entries allocated, always succeed
> + *
> + * (2) !prev, this: We're iterating at the 1st element.
> + *
> + * (3) prev, !this: We're iterating at the last element.
> + *
> + * (4) prev, this: this is the most common case, we'll try to find a hole
> + * between "prev" and "this" mapping.
> + *
> + * Note that this function assumes the last valid iova is HWADDR_MAX, but it
> + * searches linearly so it's easy to discard the result if it's not the case.
> + */
> +static void iova_tree_alloc_map_in_hole(struct IOVATreeAllocArgs *args)
> +{
> + const DMAMap *prev = args->prev, *this = args->this;
> + uint64_t hole_start, hole_last;
> +
> + if (this && this->iova + this->size < args->iova_begin) {
> + return;
> + }
> +
> + hole_start = MAX(prev ? prev->iova + prev->size + 1 : 0, args->iova_begin);
> + hole_last = this ? this->iova : HWADDR_MAX;
Do we need to use iova_last instead of HWADDR_MAX?
> +
> + if (hole_last - hole_start > args->new_size) {
> + args->iova_result = hole_start;
> + args->iova_found = true;
> + }
> +}
> +
> +/**
> + * Foreach dma node in the tree, compare if there is a hole with its previous
> + * node (or minimum iova address allowed) and the node.
> + *
> + * @key Node iterating
> + * @value Node iterating
> + * @pargs Struct to communicate with the outside world
> + *
> + * Return: false to keep iterating, true if needs break.
> + */
> +static gboolean iova_tree_alloc_traverse(gpointer key, gpointer value,
> + gpointer pargs)
> +{
> + struct IOVATreeAllocArgs *args = pargs;
> + DMAMap *node = value;
> +
> + assert(key == value);
> +
> + iova_tree_alloc_args_iterate(args, node);
> + iova_tree_alloc_map_in_hole(args);
> + return args->iova_found;
> +}
> +
> +int iova_tree_alloc_map(IOVATree *tree, DMAMap *map, hwaddr iova_begin,
> + hwaddr iova_last)
> +{
> + struct IOVATreeAllocArgs args = {
> + .new_size = map->size,
> + .iova_begin = iova_begin,
> + };
> +
> + assert(iova_begin < iova_last);
Should we use "<=" here, otherwise we disallow allocate the size of 1.
And maybe we should return error instead of assert.
> +
> + /*
> + * Find a valid hole for the mapping
> + *
> + * Assuming low iova_begin, so no need to do a binary search to
> + * locate the first node.
> + *
> + * TODO: Replace all this with g_tree_node_first/next/last when available
> + * (from glib since 2.68). To do it with g_tree_foreach complicates the
> + * code a lot.
> + *
One more question
The current code looks work but still a little bit complicated to be
reviewed. Looking at the missing helpers above, if the add and remove
are seldom. I wonder if we can simply do
g_tree_foreach() during each add/del to build a sorted list then we can
emulate g_tree_node_first/next/last easily?
> + */
> + g_tree_foreach(tree->tree, iova_tree_alloc_traverse, &args);
> + if (!args.iova_found) {
> + /*
> + * Either tree is empty or the last hole is still not checked.
> + * g_tree_foreach does not compare (last, iova_end] range, so we check
"(last, iova_last]" ?
Thanks
> + * it here.
> + */
> + iova_tree_alloc_args_iterate(&args, NULL);
> + iova_tree_alloc_map_in_hole(&args);
> + }
> +
> + if (!args.iova_found || args.iova_result + map->size > iova_last) {
> + return IOVA_ERR_NOMEM;
> + }
> +
> + map->iova = args.iova_result;
> + return iova_tree_insert(tree, map);
> +}
> +
> void iova_tree_destroy(IOVATree *tree)
> {
> g_tree_destroy(tree->tree);
On Mon, Feb 28, 2022 at 7:39 AM Jason Wang <jasowang@redhat.com> wrote:
>
>
> 在 2022/2/27 下午9:41, Eugenio Pérez 写道:
> > This iova tree function allows it to look for a hole in allocated
> > regions and return a totally new translation for a given translated
> > address.
> >
> > It's usage is mainly to allow devices to access qemu address space,
> > remapping guest's one into a new iova space where qemu can add chunks of
> > addresses.
> >
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > Reviewed-by: Peter Xu <peterx@redhat.com>
> > ---
> > include/qemu/iova-tree.h | 18 ++++++
> > util/iova-tree.c | 133 +++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 151 insertions(+)
> >
> > diff --git a/include/qemu/iova-tree.h b/include/qemu/iova-tree.h
> > index 8249edd764..a623136cd8 100644
> > --- a/include/qemu/iova-tree.h
> > +++ b/include/qemu/iova-tree.h
> > @@ -29,6 +29,7 @@
> > #define IOVA_OK (0)
> > #define IOVA_ERR_INVALID (-1) /* Invalid parameters */
> > #define IOVA_ERR_OVERLAP (-2) /* IOVA range overlapped */
> > +#define IOVA_ERR_NOMEM (-3) /* Cannot allocate */
> >
> > typedef struct IOVATree IOVATree;
> > typedef struct DMAMap {
> > @@ -119,6 +120,23 @@ const DMAMap *iova_tree_find_address(const IOVATree *tree, hwaddr iova);
> > */
> > void iova_tree_foreach(IOVATree *tree, iova_tree_iterator iterator);
> >
> > +/**
> > + * iova_tree_alloc:
>
>
> Should be iova_tree_alloc_map.
>
That's right, I'll change. It's also missing from the patch subject.
>
> > + *
> > + * @tree: the iova tree to allocate from
> > + * @map: the new map (as translated addr & size) to allocate in the iova region
> > + * @iova_begin: the minimum address of the allocation
> > + * @iova_end: the maximum addressable direction of the allocation
> > + *
> > + * Allocates a new region of a given size, between iova_min and iova_max.
> > + *
> > + * Return: Same as iova_tree_insert, but cannot overlap and can return error if
> > + * iova tree is out of free contiguous range. The caller gets the assigned iova
> > + * in map->iova.
> > + */
> > +int iova_tree_alloc_map(IOVATree *tree, DMAMap *map, hwaddr iova_begin,
> > + hwaddr iova_end);
> > +
> > /**
> > * iova_tree_destroy:
> > *
> > diff --git a/util/iova-tree.c b/util/iova-tree.c
> > index 23ea35b7a4..302b01f1cc 100644
> > --- a/util/iova-tree.c
> > +++ b/util/iova-tree.c
> > @@ -16,6 +16,39 @@ struct IOVATree {
> > GTree *tree;
> > };
> >
> > +/* Args to pass to iova_tree_alloc foreach function. */
> > +struct IOVATreeAllocArgs {
> > + /* Size of the desired allocation */
> > + size_t new_size;
> > +
> > + /* The minimum address allowed in the allocation */
> > + hwaddr iova_begin;
> > +
> > + /* Map at the left of the hole, can be NULL if "this" is first one */
> > + const DMAMap *prev;
> > +
> > + /* Map at the right of the hole, can be NULL if "prev" is the last one */
> > + const DMAMap *this;
> > +
> > + /* If found, we fill in the IOVA here */
> > + hwaddr iova_result;
> > +
> > + /* Whether have we found a valid IOVA */
> > + bool iova_found;
> > +};
> > +
> > +/**
> > + * Iterate args to the next hole
> > + *
> > + * @args The alloc arguments
> > + * @next The next mapping in the tree. Can be NULL to signal the last one
> > + */
> > +static void iova_tree_alloc_args_iterate(struct IOVATreeAllocArgs *args,
> > + const DMAMap *next) {
> > + args->prev = args->this;
> > + args->this = next;
> > +}
> > +
> > static int iova_tree_compare(gconstpointer a, gconstpointer b, gpointer data)
> > {
> > const DMAMap *m1 = a, *m2 = b;
> > @@ -107,6 +140,106 @@ int iova_tree_remove(IOVATree *tree, const DMAMap *map)
> > return IOVA_OK;
> > }
> >
> > +/**
> > + * Try to find an unallocated IOVA range between prev and this elements.
> > + *
> > + * @args Arguments to allocation
> > + *
> > + * Cases:
> > + *
> > + * (1) !prev, !this: No entries allocated, always succeed
> > + *
> > + * (2) !prev, this: We're iterating at the 1st element.
> > + *
> > + * (3) prev, !this: We're iterating at the last element.
> > + *
> > + * (4) prev, this: this is the most common case, we'll try to find a hole
> > + * between "prev" and "this" mapping.
> > + *
> > + * Note that this function assumes the last valid iova is HWADDR_MAX, but it
> > + * searches linearly so it's easy to discard the result if it's not the case.
> > + */
> > +static void iova_tree_alloc_map_in_hole(struct IOVATreeAllocArgs *args)
> > +{
> > + const DMAMap *prev = args->prev, *this = args->this;
> > + uint64_t hole_start, hole_last;
> > +
> > + if (this && this->iova + this->size < args->iova_begin) {
> > + return;
> > + }
> > +
> > + hole_start = MAX(prev ? prev->iova + prev->size + 1 : 0, args->iova_begin);
> > + hole_last = this ? this->iova : HWADDR_MAX;
>
>
> Do we need to use iova_last instead of HWADDR_MAX?
>
If I re-add iova_last to this function, this first part is the same as
RFC v5. The only difference would be iova_found.
To simplify this function, I extracted the iova_last check to
iova_tree_alloc_map. I thought this was closer to what you proposed.
As a disadvantage, the search could go beyond iova_last, but this
should not be common.
I'm ok with both versions.
>
> > +
> > + if (hole_last - hole_start > args->new_size) {
> > + args->iova_result = hole_start;
> > + args->iova_found = true;
> > + }
> > +}
> > +
> > +/**
> > + * Foreach dma node in the tree, compare if there is a hole with its previous
> > + * node (or minimum iova address allowed) and the node.
> > + *
> > + * @key Node iterating
> > + * @value Node iterating
> > + * @pargs Struct to communicate with the outside world
> > + *
> > + * Return: false to keep iterating, true if needs break.
> > + */
> > +static gboolean iova_tree_alloc_traverse(gpointer key, gpointer value,
> > + gpointer pargs)
> > +{
> > + struct IOVATreeAllocArgs *args = pargs;
> > + DMAMap *node = value;
> > +
> > + assert(key == value);
> > +
> > + iova_tree_alloc_args_iterate(args, node);
> > + iova_tree_alloc_map_in_hole(args);
> > + return args->iova_found;
> > +}
> > +
> > +int iova_tree_alloc_map(IOVATree *tree, DMAMap *map, hwaddr iova_begin,
> > + hwaddr iova_last)
> > +{
> > + struct IOVATreeAllocArgs args = {
> > + .new_size = map->size,
> > + .iova_begin = iova_begin,
> > + };
> > +
> > + assert(iova_begin < iova_last);
>
>
> Should we use "<=" here, otherwise we disallow allocate the size of 1.
>
> And maybe we should return error instead of assert.
>
Right, I'll replace both.
>
> > +
> > + /*
> > + * Find a valid hole for the mapping
> > + *
> > + * Assuming low iova_begin, so no need to do a binary search to
> > + * locate the first node.
> > + *
> > + * TODO: Replace all this with g_tree_node_first/next/last when available
> > + * (from glib since 2.68). To do it with g_tree_foreach complicates the
> > + * code a lot.
> > + *
>
>
> One more question
>
> The current code looks work but still a little bit complicated to be
> reviewed. Looking at the missing helpers above, if the add and remove
> are seldom. I wonder if we can simply do
>
> g_tree_foreach() during each add/del to build a sorted list then we can
> emulate g_tree_node_first/next/last easily?
>
This sounds a lot like the method in v1 [1] :).
But it didn't use the O(N) foreach, since we can locate the new node's
previous element looking for the upper bound of iova-1, maintaining
the insertion's complexity O(log(N)). The function g_tree_upper_bound
is added in Glib version 2.68, so the proposed version will be deleted
sooner or later.
Also the deletion keeps being O(log(N)) since deleting a node in QLIST is O(1).
>
> > + */
> > + g_tree_foreach(tree->tree, iova_tree_alloc_traverse, &args);
> > + if (!args.iova_found) {
> > + /*
> > + * Either tree is empty or the last hole is still not checked.
> > + * g_tree_foreach does not compare (last, iova_end] range, so we check
>
>
> "(last, iova_last]" ?
>
Right, I'll change it too.
Thanks!
[1] https://www.mail-archive.com/qemu-devel@nongnu.org/msg863699.html
[2] https://docs.gtk.org/glib/method.Tree.upper_bound.html
> Thanks
>
>
> > + * it here.
> > + */
> > + iova_tree_alloc_args_iterate(&args, NULL);
> > + iova_tree_alloc_map_in_hole(&args);
> > + }
> > +
> > + if (!args.iova_found || args.iova_result + map->size > iova_last) {
> > + return IOVA_ERR_NOMEM;
> > + }
> > +
> > + map->iova = args.iova_result;
> > + return iova_tree_insert(tree, map);
> > +}
> > +
> > void iova_tree_destroy(IOVATree *tree)
> > {
> > g_tree_destroy(tree->tree);
>
在 2022/3/1 下午6:06, Eugenio Perez Martin 写道: >>> + >>> + /* >>> + * Find a valid hole for the mapping >>> + * >>> + * Assuming low iova_begin, so no need to do a binary search to >>> + * locate the first node. >>> + * >>> + * TODO: Replace all this with g_tree_node_first/next/last when available >>> + * (from glib since 2.68). To do it with g_tree_foreach complicates the >>> + * code a lot. >>> + * >> One more question >> >> The current code looks work but still a little bit complicated to be >> reviewed. Looking at the missing helpers above, if the add and remove >> are seldom. I wonder if we can simply do >> >> g_tree_foreach() during each add/del to build a sorted list then we can >> emulate g_tree_node_first/next/last easily? >> > This sounds a lot like the method in v1 [1]:). Oh, right. I missed that and it takes time to recover the memory. > > But it didn't use the O(N) foreach, since we can locate the new node's > previous element looking for the upper bound of iova-1, maintaining > the insertion's complexity O(log(N)). The function g_tree_upper_bound > is added in Glib version 2.68, so the proposed version will be deleted > sooner or later. > > Also the deletion keeps being O(log(N)) since deleting a node in QLIST is O(1). Yes, so I think we can leave the log as is and do optimization on top. Thanks >
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