From dfb09f9b7ab03fd367740e541a5caf830ed56726 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Fri, 5 Aug 2011 15:15:08 +0200 Subject: 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 Link: http://lkml.kernel.org/r/1312550110-24160-2-git-send-email-bp@amd64.org Signed-off-by: H. Peter Anvin --- arch/x86/kernel/cpu/amd.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'arch/x86/kernel/cpu') diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index b13ed39..b0234bc 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -458,6 +458,19 @@ static void __cpuinit early_init_amd(struct cpuinfo_x86 *c) "with P0 frequency!\n"); } } + + if (c->x86 == 0x15) { + unsigned long upperbit; + u32 cpuid, assoc; + + cpuid = cpuid_edx(0x80000005); + assoc = cpuid >> 16 & 0xff; + upperbit = ((cpuid >> 24) << 10) / assoc; + + va_align.mask = (upperbit - 1) & PAGE_MASK; + va_align.flags = ALIGN_VA_32 | ALIGN_VA_64; + + } } static void __cpuinit init_amd(struct cpuinfo_x86 *c) -- cgit v1.1