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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 15651291a2 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>
This commit is contained in:
Myron Stowe 2010-10-21 14:24:14 -06:00 committed by Len Brown
parent 78cdb3ed40
commit 4a3cba5e72
1 changed files with 51 additions and 11 deletions
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62
drivers/acpi/osl.c
View File

@ -104,6 +104,7 @@ struct acpi_ioremap {
void __iomem *virt;
acpi_physical_address phys;
acpi_size size;
struct kref ref;
};
static LIST_HEAD(acpi_ioremaps);
@ -245,15 +246,28 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
}
/* 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 @@ acpi_map_lookup_virt(void __iomem *virt, acpi_size size)
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 @@ acpi_map_lookup_virt(void __iomem *virt, acpi_size size)
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 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
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 @@ acpi_os_map_memory(acpi_physical_address phys, acpi_size size)
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 @@ void __ref acpi_os_unmap_memory(void __iomem *virt, acpi_size size)
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);