Merge branch 'perfcounters-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'perfcounters-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (60 commits)
  perf tools: Avoid unnecessary work in directory lookups
  perf stat: Clean up statistics calculations a bit more
  perf stat: More advanced variance computation
  perf stat: Use stddev_mean in stead of stddev
  perf stat: Remove the limit on repeat
  perf stat: Change noise calculation to use stddev
  x86, perf_counter, bts: Do not allow kernel BTS tracing for now
  x86, perf_counter, bts: Correct pointer-to-u64 casts
  x86, perf_counter, bts: Fail if BTS is not available
  perf_counter: Fix output-sharing error path
  perf trace: Fix read_string()
  perf trace: Print out in nanoseconds
  perf tools: Seek to the end of the header area
  perf trace: Fix parsing of perf.data
  perf trace: Sample timestamps as well
  perf_counter: Introduce new (non-)paranoia level to allow raw tracepoint access
  perf trace: Sample the CPU too
  perf tools: Work around strict aliasing related warnings
  perf tools: Clean up warnings list in the Makefile
  perf tools: Complete support for dynamic strings
  ...

arch/x86/include/asm/perf_counter.h

@@ -84,6 +84,16 @@ union cpuid10_edx {
 #define MSR_ARCH_PERFMON_FIXED_CTR2			0x30b
 #define X86_PMC_IDX_FIXED_BUS_CYCLES			(X86_PMC_IDX_FIXED + 2)
 
+/*
+ * We model BTS tracing as another fixed-mode PMC.
+ *
+ * We choose a value in the middle of the fixed counter range, since lower
+ * values are used by actual fixed counters and higher values are used
+ * to indicate other overflow conditions in the PERF_GLOBAL_STATUS msr.
+ */
+#define X86_PMC_IDX_FIXED_BTS				(X86_PMC_IDX_FIXED + 16)
+
+
 #ifdef CONFIG_PERF_COUNTERS
 extern void init_hw_perf_counters(void);
 extern void perf_counters_lapic_init(void);