From: Suresh Siddha Date: Sat, 26 Apr 2008 00:07:22 +0000 (-0700) Subject: x86 PAT: fix performance drop for glx, use UC minus for ioremap(), ioremap_nocache... X-Git-Tag: v2.6.26-rc1~98^2~7 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=de33c442ed2a465d2d7804b26dafd2eec067aa34;p=linux-2.6-omap-h63xx.git 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 Signed-off-by: Venkatesh Pallipadi Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index 0be9f9c59aa..6d02a36e5e4 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 bd5e05c654d..60bcb5b6a37 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 94f6c73a53d..8af0f0bae2a 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);