diff options
| author | Suresh Siddha <suresh.b.siddha@intel.com> | 2008-03-26 03:39:12 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-03-27 00:23:41 +0300 |
| commit | d546b67a940eb42a99f56b86c5cd8d47c8348c2a (patch) | |
| tree | 5382b2d1800756aedad0a25643081de2eec6a4bf /arch | |
| parent | 76c324182bbd29dfe4298ca65efb15be18055df1 (diff) | |
| download | linux-d546b67a940eb42a99f56b86c5cd8d47c8348c2a.tar.xz | |
x86: fix performance drop for glx
fix the 3D performance drop reported at:
http://bugzilla.kernel.org/show_bug.cgi?id=10328
fb drivers are using ioremap()/ioremap_nocache(), followed by mtrr_add with
WC attribute. Recent changes in page attribute code made both
ioremap()/ioremap_nocache() mappings as UC (instead of previous UC-). This
breaks the graphics performance, as the effective memory type is UC instead
of expected WC.
The correct way to fix this is to add ioremap_wc() (which uses UC- in the
absence of PAT kernel support and WC with PAT) and change all the
fb drivers to use this new ioremap_wc() API.
We can take this correct and longer route for post 2.6.25. For now,
revert back to the UC- behavior for ioremap/ioremap_nocache.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/mm/ioremap.c | 6 | ||||
| -rw-r--r-- | arch/x86/mm/pageattr.c | 2 |
2 files changed, 6 insertions, 2 deletions
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index 4afaba0ed722..794895c6dcc9 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -137,7 +137,11 @@ static void __iomem *__ioremap(resource_size_t phys_addr, unsigned long size, switch (mode) { case IOR_MODE_UNCACHED: default: - prot = PAGE_KERNEL_NOCACHE; + /* + * FIXME: we will use UC MINUS for now, as video fb drivers + * depend on it. Upcoming ioremap_wc() will fix this behavior. + */ + prot = PAGE_KERNEL_UC_MINUS; break; case IOR_MODE_CACHED: prot = PAGE_KERNEL; diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 14e48b5a94ba..7b79f6be4e7d 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -771,7 +771,7 @@ static inline int change_page_attr_clear(unsigned long addr, int numpages, int set_memory_uc(unsigned long addr, int numpages) { return change_page_attr_set(addr, numpages, - __pgprot(_PAGE_PCD | _PAGE_PWT)); + __pgprot(_PAGE_PCD)); } EXPORT_SYMBOL(set_memory_uc); |