On Sun, 2009-05-10 at 08:30 +0200, Ingo Molnar wrote: > * Jaswinder Singh Rajput <jaswinder@xxxxxxxxxx> wrote: > > > > #define X86_FEATURE_ARCH_PERFMON (3*32+11) /* Intel Architectural PerfMon */ > > > should be replaced by > > > #define X86_FEATURE_ARCH_PERFMON (3*32+11) /* Performace Monitor */ > > > > > > All x86 cpus which support performance monitor should set this feature. > > > > > > > Currently X86_FEATURE_ARCH_PERFMON is enabled for >= Intel Core2 > > > > But Performance monitor is almost supported by all Intel > > processors. I am adding few MSRs list for reference to see > > complete list please check arch/x86/kernel/cpu/cpu_debug.c > > I think you are confusing two things: > > - The 'architectural perfmon' CPU flag, enumerated in CPUID. (this > is a relatively new CPUID flag that only Intel CPUs at around > Core2 and later will report.) > > - The concept of 'performance monitoring' - which has been present > in various x86 CPUs starting at the original Pentium (P5) 15 years > ago or so. > > The X86_FEATURE_ARCH_PERFMON flag is for the architectural perfmon > CPUID feature. If you execute CPUID you'll get that from the CPU - > on Core2 and later Intel CPUs. You wont get it on AMD CPUs. You wont > get it on earlier Intel CPUs. > > And since 'Architectural Performance Monitoring' is an Intel only > thing, it would not be correct to do as if AMD had the same thing. > AMD has something _similar_, but not quite the same. > Thanks for clarification. There is one more way to check performance monitor support for Intel by using IA32_MISC_ENABLE MSR (0x1A0) bit 7 tells whether performance monitoring is available or not. But IA32_MISC_ENABLE MSR (0x1A0) is not available for Pentium and P6. So better I will add new cpufeature for performance monitoring for x86: X86_FEATURE_PERFMON : Performance monitor support -- JSR -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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