This avoids the need to update cyclictest.c for every new CPU family, at
the cost of generating bogus SMI numbers on pre-2008 CPUs. Based on the
comment from Daniel Bristot de Oliviera:
> When I added that option the smi was a relatively new thing...
> nowadays I think it is pretty standard...
> so simplifying it is a good thing.
---
src/cyclictest/cyclictest.c | 91 ++++---------------------------------
1 file changed, 8 insertions(+), 83 deletions(-)
diff --git a/src/cyclictest/cyclictest.c b/src/cyclictest/cyclictest.c
index 33fac3b..8a96339 100644
--- a/src/cyclictest/cyclictest.c
+++ b/src/cyclictest/cyclictest.c
@@ -404,7 +404,14 @@ static int get_smi_counter(int fd, unsigned long *counter)
#include <cpuid.h>
-/* Based on turbostat's check */
+/* Guess if the CPU has an SMI counter in the model-specific registers (MSR).
+ *
+ * This is true for Intel x86 CPUs after Nehalem (2008). However, it's not
+ * possible to detect the feature directly, (or at least, turbostat.c doesn't
+ * know how to do it either) so we assume it's true for all x86 CPUs.
+ * Previously, this function had an explicit allowlist, which required updates
+ * every time a new CPU generation was released.
+ */
static int has_smi_counter(void)
{
unsigned int ebx, ecx, edx, max_level;
@@ -428,88 +435,6 @@ static int has_smi_counter(void)
if (!(edx & (1 << 5)))
return 0;
- model = (((fms >> 16) & 0xf) << 4) + ((fms >> 4) & 0xf);
-
- /* Based on intel_model_duplicates */
- switch (model) {
- case 0x1A: /* INTEL_FAM6_NEHALEM_EP */
- case 0x1E: /* INTEL_FAM6_NEHALEM */
- case 0x1F: /* Core i7 and i5 Processor - Nehalem */
- case 0x25: /* INTEL_FAM6_WESTMERE */
- case 0x2C: /* INTEL_FAM6_WESTMERE_EP */
- model = 0x1E; /* INTEL_FAM6_NEHALEM */
- break;
- case 0x2E: /* INTEL_FAM6_NEHALEM_EX */
- case 0x2F: /* INTEL_FAM6_WESTMERE_EX */
- model = 0x2E; /* INTEL_FAM6_NEHALEM_EX */
- break;
- case 0x85: /* INTEL_FAM6_XEON_PHI_KNM */
- model = 0x57; /* INTEL_FAM6_XEON_PHI_KNL */
- break;
- case 0x4F: /* INTEL_FAM6_BROADWELL_X */
- case 0x56: /* INTEL_FAM6_BROADWELL_D */
- model = 0x4F; /* INTEL_FAM6_BROADWELL_X */
- break;
- case 0x4E: /* INTEL_FAM6_SKYLAKE_L */
- case 0x5E: /* INTEL_FAM6_SKYLAKE */
- case 0x8E: /* INTEL_FAM6_KABYLAKE_L */
- case 0x9E: /* INTEL_FAM6_KABYLAKE */
- case 0xA6: /* INTEL_FAM6_COMETLAKE_L */
- case 0xA5: /* INTEL_FAM6_COMETLAKE */
- model = 0x4E; /* INTEL_FAM6_SKYLAKE_L */
- break;
- case 0x7E: /* INTEL_FAM6_ICELAKE_L */
- case 0x9D: /* INTEL_FAM6_ICELAKE_NNPI */
- case 0x8C: /* INTEL_FAM6_TIGERLAKE_L */
- case 0x8D: /* INTEL_FAM6_TIGERLAKE */
- case 0xA7: /* INTEL_FAM6_ROCKETLAKE */
- case 0x8A: /* INTEL_FAM6_LAKEFIELD */
- case 0x97: /* INTEL_FAM6_ALDERLAKE */
- case 0x9A: /* INTEL_FAM6_ALDERLAKE_L */
- model = 0x66; /* INTEL_FAM6_CANNONLAKE_L */
- break;
- case 0x9C: /* INTEL_FAM6_ATOM_TREMONT_L */
- model = 0x96; /* INTEL_FAM6_ATOM_TREMONT */
- break;
- case 0x6C: /* INTEL_FAM6_ICELAKE_D */
- case 0x8F: /* INTEL_FAM6_SAPPHIRERAPIDS_X */
- model = 0x6A; /* INTEL_FAM6_ICELAKE_X */
- break;
- }
-
- /* Based on probe_nhm_msrs */
- switch (model) {
- case 0x1E: /* INTEL_FAM6_NEHALEM */
- case 0x2E: /* INTEL_FAM6_NEHALEM_EX */
- case 0x2A: /* INTEL_FAM6_SANDYBRIDGE */
- case 0x2D: /* INTEL_FAM6_SANDYBRIDGE_X */
- case 0x3A: /* INTEL_FAM6_IVYBRIDGE */
- case 0x3E: /* INTEL_FAM6_IVYBRIDGE_X */
- case 0x3C: /* INTEL_FAM6_HASWELL */
- case 0x46: /* INTEL_FAM6_HASWELL_G */
- case 0x3F: /* INTEL_FAM6_HASWELL_X */
- case 0x45: /* INTEL_FAM6_HASWELL_L */
- case 0x3D: /* INTEL_FAM6_BROADWELL */
- case 0x47: /* INTEL_FAM6_BROADWELL_G */
- case 0x4F: /* INTEL_FAM6_BROADWELL_X */
- case 0x4E: /* INTEL_FAM6_SKYLAKE_L */
- case 0x66: /* INTEL_FAM6_CANNONLAKE_L */
- case 0x55: /* INTEL_FAM6_SKYLAKE_X */
- case 0x6A: /* INTEL_FAM6_ICELAKE_X */
- case 0x37: /* INTEL_FAM6_ATOM_SILVERMONT */
- case 0x4D: /* INTEL_FAM6_ATOM_SILVERMONT_D */
- case 0x4C: /* INTEL_FAM6_ATOM_AIRMONT */
- case 0x57: /* INTEL_FAM6_XEON_PHI_KNL */
- case 0x5C: /* INTEL_FAM6_ATOM_GOLDMONT */
- case 0x7A: /* INTEL_FAM6_ATOM_GOLDMONT_PLUS */
- case 0x5F: /* INTEL_FAM6_ATOM_GOLDMONT_D */
- case 0x96: /* INTEL_FAM6_ATOM_TREMONT */
- case 0x86: /* INTEL_FAM6_ATOM_TREMONT_D */
- break;
- default:
- return 0;
- }
-
return 1;
}
#else
--
2.44.0.rc0.258.g7320e95886-goog
