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authorSuresh Siddha <suresh.b.siddha@intel.com>2008-04-25 17:07:22 -0700
committerIngo Molnar <mingo@elte.hu>2008-04-30 23:15:35 +0200
commitde33c442ed2a465d2d7804b26dafd2eec067aa34 (patch)
tree02a9cb2b96d0ad535f0dbfbdccc35afe21aa052e /arch
parentb9b39bfba5b0de3418305f01cfa7bc55a16004e1 (diff)
downloadop-kernel-dev-de33c442ed2a465d2d7804b26dafd2eec067aa34.zip
op-kernel-dev-de33c442ed2a465d2d7804b26dafd2eec067aa34.tar.gz
x86 PAT: fix performance drop for glx, use UC minus for ioremap(), ioremap_nocache() and pci_mmap_page_range()
Use UC_MINUS for ioremap(), ioremap_nocache() instead of strong UC. Once all the X drivers move to ioremap_wc(), we can go back to strong UC semantics for ioremap() and ioremap_nocache(). To avoid attribute aliasing issues, pci_mmap_page_range() will also use UC_MINUS for default non write-combining mapping request. Next steps: a) change all the video drivers using ioremap() or ioremap_nocache() and adding WC MTTR using mttr_add() to ioremap_wc() b) for strict usage, we can go back to strong uc semantics for ioremap() and ioremap_nocache() after some grace period for completing step-a. c) user level X server needs to use the appropriate method for setting up WC mapping (like using resourceX_wc sysfs file instead of adding MTRR for WC and using /dev/mem or resourceX under /sys) Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/mm/ioremap.c20
-rw-r--r--arch/x86/mm/pageattr.c10
-rw-r--r--arch/x86/pci/i386.c12
3 files changed, 33 insertions, 9 deletions
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 0be9f9c..6d02a36 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -176,11 +176,11 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
/*
* Do not fallback to certain memory types with certain
* requested type:
- * - request is uncached, return cannot be write-back
- * - request is uncached, return cannot be write-combine
+ * - request is uc-, return cannot be write-back
+ * - request is uc-, return cannot be write-combine
* - request is write-combine, return cannot be write-back
*/
- if ((prot_val == _PAGE_CACHE_UC &&
+ if ((prot_val == _PAGE_CACHE_UC_MINUS &&
(new_prot_val == _PAGE_CACHE_WB ||
new_prot_val == _PAGE_CACHE_WC)) ||
(prot_val == _PAGE_CACHE_WC &&
@@ -201,6 +201,9 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
default:
prot = PAGE_KERNEL_NOCACHE;
break;
+ case _PAGE_CACHE_UC_MINUS:
+ prot = PAGE_KERNEL_UC_MINUS;
+ break;
case _PAGE_CACHE_WC:
prot = PAGE_KERNEL_WC;
break;
@@ -255,7 +258,16 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
*/
void __iomem *ioremap_nocache(resource_size_t phys_addr, unsigned long size)
{
- return __ioremap_caller(phys_addr, size, _PAGE_CACHE_UC,
+ /*
+ * Ideally, this should be:
+ * pat_wc_enabled ? _PAGE_CACHE_UC : _PAGE_CACHE_UC_MINUS;
+ *
+ * Till we fix all X drivers to use ioremap_wc(), we will use
+ * UC MINUS.
+ */
+ unsigned long val = _PAGE_CACHE_UC_MINUS;
+
+ return __ioremap_caller(phys_addr, size, val,
__builtin_return_address(0));
}
EXPORT_SYMBOL(ioremap_nocache);
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index bd5e05c..60bcb5b 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -777,14 +777,20 @@ static inline int change_page_attr_clear(unsigned long addr, int numpages,
int _set_memory_uc(unsigned long addr, int numpages)
{
+ /*
+ * for now UC MINUS. see comments in ioremap_nocache()
+ */
return change_page_attr_set(addr, numpages,
- __pgprot(_PAGE_CACHE_UC));
+ __pgprot(_PAGE_CACHE_UC_MINUS));
}
int set_memory_uc(unsigned long addr, int numpages)
{
+ /*
+ * for now UC MINUS. see comments in ioremap_nocache()
+ */
if (reserve_memtype(addr, addr + numpages * PAGE_SIZE,
- _PAGE_CACHE_UC, NULL))
+ _PAGE_CACHE_UC_MINUS, NULL))
return -EINVAL;
return _set_memory_uc(addr, numpages);
diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index 94f6c73..8af0f0b 100644
--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -301,6 +301,13 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
prot = pgprot_val(vma->vm_page_prot);
if (pat_wc_enabled && write_combine)
prot |= _PAGE_CACHE_WC;
+ else if (pat_wc_enabled)
+ /*
+ * ioremap() and ioremap_nocache() defaults to UC MINUS for now.
+ * To avoid attribute conflicts, request UC MINUS here
+ * aswell.
+ */
+ prot |= _PAGE_CACHE_UC_MINUS;
else if (boot_cpu_data.x86 > 3)
prot |= _PAGE_CACHE_UC;
@@ -319,9 +326,8 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
* - request is uncached, return cannot be write-combine
* - request is write-combine, return cannot be write-back
*/
- if ((flags == _PAGE_CACHE_UC &&
- (new_flags == _PAGE_CACHE_WB ||
- new_flags == _PAGE_CACHE_WC)) ||
+ if ((flags == _PAGE_CACHE_UC_MINUS &&
+ (new_flags == _PAGE_CACHE_WB)) ||
(flags == _PAGE_CACHE_WC &&
new_flags == _PAGE_CACHE_WB)) {
free_memtype(addr, addr+len);
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