ACPI: Page based coalescing of I/O remappings optimization
This patch optimizes ACPI MMIO remappings by keeping track of the
remappings on a PAGE_SIZE granularity.
When an ioremap() occurs, the underlying infrastructure works on a 'page'
based granularity. As such, an ioremap() request for 1 byte for example,
will end up mapping in an entire (PAGE_SIZE) page. Huang Ying took
advantage of this in commit 15651291a2f8c11e7e6a42d8bfde7a213ff13262 by
checking if subsequent ioremap() requests reside within any of the list's
existing remappings still in place, and if so, incrementing a reference
count on the existing mapping as opposed to performing another ioremap().
Signed-off-by: Myron Stowe <myron.stowe@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 3282689..885e222 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -104,6 +104,7 @@
void __iomem *virt;
acpi_physical_address phys;
acpi_size size;
+ struct kref ref;
};
static LIST_HEAD(acpi_ioremaps);
@@ -245,15 +246,28 @@
}
/* Must be called with 'acpi_ioremap_lock' or RCU read lock held. */
-static void __iomem *
-acpi_map_vaddr_lookup(acpi_physical_address phys, acpi_size size)
+static struct acpi_ioremap *
+acpi_map_lookup(acpi_physical_address phys, acpi_size size)
{
struct acpi_ioremap *map;
list_for_each_entry_rcu(map, &acpi_ioremaps, list)
if (map->phys <= phys &&
phys + size <= map->phys + map->size)
- return map->virt + (phys - map->phys);
+ return map;
+
+ return NULL;
+}
+
+/* Must be called with 'acpi_ioremap_lock' or RCU read lock held. */
+static void __iomem *
+acpi_map_vaddr_lookup(acpi_physical_address phys, unsigned int size)
+{
+ struct acpi_ioremap *map;
+
+ map = acpi_map_lookup(phys, size);
+ if (map)
+ return map->virt + (phys - map->phys);
return NULL;
}
@@ -265,7 +279,8 @@
struct acpi_ioremap *map;
list_for_each_entry_rcu(map, &acpi_ioremaps, list)
- if (map->virt == virt && map->size == size)
+ if (map->virt <= virt &&
+ virt + size <= map->virt + map->size)
return map;
return NULL;
@@ -274,9 +289,10 @@
void __iomem *__init_refok
acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
{
- struct acpi_ioremap *map;
- unsigned long flags;
+ struct acpi_ioremap *map, *tmp_map;
+ unsigned long flags, pg_sz;
void __iomem *virt;
+ phys_addr_t pg_off;
if (phys > ULONG_MAX) {
printk(KERN_ERR PREFIX "Cannot map memory that high\n");
@@ -290,7 +306,9 @@
if (!map)
return NULL;
- virt = ioremap(phys, size);
+ pg_off = round_down(phys, PAGE_SIZE);
+ pg_sz = round_up(phys + size, PAGE_SIZE) - pg_off;
+ virt = ioremap(pg_off, pg_sz);
if (!virt) {
kfree(map);
return NULL;
@@ -298,21 +316,40 @@
INIT_LIST_HEAD(&map->list);
map->virt = virt;
- map->phys = phys;
- map->size = size;
+ map->phys = pg_off;
+ map->size = pg_sz;
+ kref_init(&map->ref);
spin_lock_irqsave(&acpi_ioremap_lock, flags);
+ /* Check if page has already been mapped. */
+ tmp_map = acpi_map_lookup(phys, size);
+ if (tmp_map) {
+ kref_get(&tmp_map->ref);
+ spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
+ iounmap(map->virt);
+ kfree(map);
+ return tmp_map->virt + (phys - tmp_map->phys);
+ }
list_add_tail_rcu(&map->list, &acpi_ioremaps);
spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
- return virt;
+ return map->virt + (phys - map->phys);
}
EXPORT_SYMBOL_GPL(acpi_os_map_memory);
+static void acpi_kref_del_iomap(struct kref *ref)
+{
+ struct acpi_ioremap *map;
+
+ map = container_of(ref, struct acpi_ioremap, ref);
+ list_del_rcu(&map->list);
+}
+
void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size)
{
struct acpi_ioremap *map;
unsigned long flags;
+ int del;
if (!acpi_gbl_permanent_mmap) {
__acpi_unmap_table(virt, size);
@@ -328,9 +365,12 @@
return;
}
- list_del_rcu(&map->list);
+ del = kref_put(&map->ref, acpi_kref_del_iomap);
spin_unlock_irqrestore(&acpi_ioremap_lock, flags);
+ if (!del)
+ return;
+
synchronize_rcu();
iounmap(map->virt);
kfree(map);