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iommu_gas: make iommu_gas_lowermatch non-recursive

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Change the recursive implementation to one that uses parent pointers
to walk back up the rb-tree, to slightly improve performance.

Reviewed by:	alc, kib
MFC after:	3 weeks
Differential Revision:	https://reviews.freebsd.org/D35486
This commit is contained in:
Doug Moore 2022-06-15 11:32:56 -05:00
parent f9e62419f6
commit f979ad0030
1 changed files with 53 additions and 23 deletions
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76
sys/dev/iommu/iommu_gas.c
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@ -376,35 +376,65 @@ iommu_gas_match_insert(struct iommu_gas_match_args *a)
static int
iommu_gas_lowermatch(struct iommu_gas_match_args *a, struct iommu_map_entry *entry)
{
struct iommu_map_entry *child;
struct iommu_map_entry *first;
iommu_gaddr_t min_free;
/*
* If the subtree doesn't have free space for the requested allocation
* plus two guard pages, give up.
* plus two guard pages, skip it.
*/
if (entry->free_down < 2 * IOMMU_PAGE_SIZE +
roundup2(a->size + a->offset, IOMMU_PAGE_SIZE))
return (ENOMEM);
if (entry->first >= a->common->lowaddr)
return (ENOMEM);
child = RB_LEFT(entry, rb_entry);
if (child != NULL && 0 == iommu_gas_lowermatch(a, child))
return (0);
if (child != NULL && child->last < a->common->lowaddr &&
iommu_gas_match_one(a, child->last, entry->start,
a->common->lowaddr)) {
iommu_gas_match_insert(a);
return (0);
min_free = 2 * IOMMU_PAGE_SIZE +
roundup2(a->size + a->offset, IOMMU_PAGE_SIZE);
/* Find the first entry that could abut a big-enough range. */
first = NULL;
while (entry != NULL && entry->free_down >= min_free) {
first = entry;
entry = RB_LEFT(entry, rb_entry);
}
child = RB_RIGHT(entry, rb_entry);
if (child != NULL && entry->end < a->common->lowaddr &&
iommu_gas_match_one(a, entry->end, child->first,
a->common->lowaddr)) {
iommu_gas_match_insert(a);
return (0);
/*
* Walk the big-enough ranges until one satisfies alignment
* requirements, or violates lowaddr address requirement.
*/
entry = first;
while (entry != NULL) {
if ((first = RB_LEFT(entry, rb_entry)) != NULL) {
if (first->last >= a->common->lowaddr) {
/* All remaining ranges >= lowaddr */
break;
}
if (iommu_gas_match_one(a, first->last, entry->start,
a->common->lowaddr)) {
iommu_gas_match_insert(a);
return (0);
}
}
if (entry->end >= a->common->lowaddr) {
/* All remaining ranges >= lowaddr */
break;
}
if ((first = RB_RIGHT(entry, rb_entry)) != NULL &&
iommu_gas_match_one(a, entry->end, first->first,
a->common->lowaddr)) {
iommu_gas_match_insert(a);
return (0);
}
/* Find the next entry that might abut a big-enough range. */
if (first != NULL && first->free_down >= min_free) {
/* Find next entry in right subtree. */
do
entry = first;
while ((first = RB_LEFT(entry, rb_entry)) != NULL &&
first->free_down >= min_free);
} else {
/* Find next entry in a left-parent ancestor. */
while ((first = RB_PARENT(entry, rb_entry)) != NULL &&
entry == RB_RIGHT(first, rb_entry))
entry = first;
entry = first;
}
}
if (child != NULL && 0 == iommu_gas_lowermatch(a, child))
return (0);
return (ENOMEM);
}