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authorBorislav Petkov <borislav.petkov@amd.com>2011-08-05 15:15:08 +0200
committerH. Peter Anvin <hpa@linux.intel.com>2011-08-05 12:26:44 -0700
commitdfb09f9b7ab03fd367740e541a5caf830ed56726 (patch)
tree8bd8fdbbf3fb67f7d0aed73a1e8e1c7034ed2d54 /arch/x86/mm/mmap.c
parent13f9a3737c903ace57d8aaebe81a3bbaeb0aa0a2 (diff)
x86, amd: Avoid cache aliasing penalties on AMD family 15h
This patch provides performance tuning for the "Bulldozer" CPU. With its shared instruction cache there is a chance of generating an excessive number of cache cross-invalidates when running specific workloads on the cores of a compute module. This excessive amount of cross-invalidations can be observed if cache lines backed by shared physical memory alias in bits [14:12] of their virtual addresses, as those bits are used for the index generation. This patch addresses the issue by clearing all the bits in the [14:12] slice of the file mapping's virtual address at generation time, thus forcing those bits the same for all mappings of a single shared library across processes and, in doing so, avoids instruction cache aliases. It also adds the command line option "align_va_addr=(32|64|on|off)" with which virtual address alignment can be enabled for 32-bit or 64-bit x86 individually, or both, or be completely disabled. This change leaves virtual region address allocation on other families and/or vendors unaffected. Signed-off-by: Borislav Petkov <borislav.petkov@amd.com> Link: http://lkml.kernel.org/r/1312550110-24160-2-git-send-email-bp@amd64.org Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/mm/mmap.c')
-rw-r--r--arch/x86/mm/mmap.c15
1 files changed, 0 insertions, 15 deletions
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 1dab5194fd9..d4c07363017 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -51,21 +51,6 @@ static unsigned int stack_maxrandom_size(void)
#define MIN_GAP (128*1024*1024UL + stack_maxrandom_size())
#define MAX_GAP (TASK_SIZE/6*5)
-/*
- * True on X86_32 or when emulating IA32 on X86_64
- */
-static int mmap_is_ia32(void)
-{
-#ifdef CONFIG_X86_32
- return 1;
-#endif
-#ifdef CONFIG_IA32_EMULATION
- if (test_thread_flag(TIF_IA32))
- return 1;
-#endif
- return 0;
-}
-
static int mmap_is_legacy(void)
{
if (current->personality & ADDR_COMPAT_LAYOUT)