[m-rev.] For post-commit review: Print the CPU's clock speed in the profiling data for the parallelism runtime.
Paul Bone
pbone at csse.unimelb.edu.au
Fri Nov 6 16:39:27 AEDT 2009
For post-commit review.
Print the CPU's clock speed in the profiling data for the parallelism runtime.
While the CPU's clock speed is not always the speed that the CPU operates at,
it is the number of TSC units per second when the CPU supports the constant TSC
feature (see /proc/cpuinfo / CPUID). This change set is used in preparation for
upcoming work on exporting ThreadScope profiling data, see "Parallel
Performance Tuning for Haskell" - Don Jones Jr, Simon Marlow and Satnam Singh.
runtime/mercury_atomic_ops.c:
Retrieve the CPU frequency from the CPUID instruction and store it in
MR_cpu_cycles_per_sec
runtime/mercury_atomic_ops.h:
Export MR_cpu_cycles_per_sec
runtime/mercury_context.c:
Print the number of cycles per second in the parallel profiling data file
if we where able to detect it.
Index: runtime/mercury_atomic_ops.c
===================================================================
RCS file: /home/mercury1/repository/mercury/runtime/mercury_atomic_ops.c,v
retrieving revision 1.5
diff -u -p -b -r1.5 mercury_atomic_ops.c
--- runtime/mercury_atomic_ops.c 5 Nov 2009 05:47:40 -0000 1.5
+++ runtime/mercury_atomic_ops.c 6 Nov 2009 05:09:04 -0000
@@ -79,10 +79,15 @@ MR_OUTLINE_DEFN(
*/
#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
+/*
+** True if the RDTSCP and RDTSC instructions are available respectively.
+*/
static MR_bool MR_rdtscp_is_available = MR_FALSE;
static MR_bool MR_rdtsc_is_available = MR_FALSE;
#endif
+MR_uint_least64_t MR_cpu_cycles_per_sec = 0;
+
#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
/* Set this to 1 to enable some printfs below */
@@ -101,6 +106,13 @@ MR_rdtscp(MR_uint_least64_t *tsc, MR_Uns
static __inline__ void
MR_rdtsc(MR_uint_least64_t *tsc);
+/*
+** Return zero if parsing failed, otherwise return the number of cycles per
+** second.
+*/
+static MR_uint_least64_t
+parse_freq_from_x86_brand_string(char *string);
+
#endif /* __GNUC__ && (__i386__ || __x86_64__) */
extern void
@@ -108,6 +120,7 @@ MR_configure_profiling_timers(void) {
#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
MR_Unsigned a, b, c, d;
MR_Unsigned eflags, old_eflags;
+ MR_Unsigned maximum_extended_page;
/*
** Check for the CPUID instruction. CPUID is supported if we can flip bit
@@ -232,35 +245,140 @@ MR_configure_profiling_timers(void) {
*/
return;
}
+ maximum_extended_page = a;
#if MR_DEBUG_CPU_FEATURE_DETECTION
- fprintf(stderr, "Maximum extended CPUID node: 0x%x\n", a);
+ fprintf(stderr, "Maximum extended CPUID page: 0x%x\n", maximum_extended_page);
#endif
- if (a < 0x80000001)
- return;
/*
** Extended CPUID 0x80000001
**
** If EDX bit 27 is set the RDTSCP instruction is available.
*/
+ if (maximum_extended_page >= 0x80000001) {
MR_cpuid(0x80000001, 0, &a, &b, &c, &d);
#if MR_DEBUG_CPU_FEATURE_DETECTION
fprintf(stderr, "CPUID 0x80000001 EDX: 0x%x\n", d);
#endif
- if (!(d & (1 << 27)))
- return;
-
+ if ((d & (1 << 27))) {
/*
- ** Support for RDTSCP appears to be present
+ ** This processor supports RDTSCP.
*/
#if MR_DEBUG_CPU_FEATURE_DETECTION
fprintf(stderr, "RDTSCP is available\n");
#endif
MR_rdtscp_is_available = MR_TRUE;
+ }
+ }
+
+ if (maximum_extended_page >= 0x80000004) {
+ /*
+ ** 3 CPUID pages, 4 return registers each, containing 4 bytes each,
+ ** plus a null byte. Intel say they include their own null byte, but
+ ** for the cost of a single byte I feel safer using our own.
+ */
+#define CPUID_BRAND_STRING_SIZE (3*4*4 + 1)
+ char buff[CPUID_BRAND_STRING_SIZE];
+ unsigned int page;
+ unsigned int byte;
+ unsigned int shift;
+
+ /*
+ * This processor supports the brand string from which we can extract
+ * the clock speed. This algorithm is described in the Intel
+ * Instruction Set Reference, Volume 2B, Chapter 3, Pages 207-208, In
+ * particular the flow chart in figure 3-10.
+ */
+ for (page = 0; page < 3; page++) {
+ MR_cpuid(page + 0x80000002, 0, &a, &b, &c, &d);
+#if MR_DEBUG_CPU_FEATURE_DETECTION
+ fprintf(stderr, "CPUID page: 0x%.8x, eax: 0x%.8x, ebx: 0x%.8x, ecx: 0x%.8x, edx: 0x%.8x\n",
+ page + 0x80000002, a, b, c, d);
+#endif
+ for (byte = 0; byte < 4; byte++) {
+ shift = byte * 8;
+ buff[page*4*4 + 0 + byte] = (char)(0xFF & (a >> shift));
+ buff[page*4*4 + 4 + byte] = (char)(0xFF & (b >> shift));
+ buff[page*4*4 + 8 + byte] = (char)(0xFF & (c >> shift));
+ buff[page*4*4 + 12 + byte] = (char)(0xFF & (d >> shift));
+ }
+ }
+ /* Add a null byte */
+ buff[CPUID_BRAND_STRING_SIZE - 1] = 0;
+#if MR_DEBUG_CPU_FEATURE_DETECTION
+ fprintf(stderr, "CPUID Brand string: %s\n", buff);
+#endif
+
+ MR_cpu_cycles_per_sec = parse_freq_from_x86_brand_string(buff);
+#if MR_DEBUG_CPU_FEATURE_DETECTION
+ fprintf(stderr, "Cycles per second: %ld\n", MR_cpu_cycles_per_sec);
+#endif
+ }
#endif /* __GNUC__ && (__i386__ || __x86_64__) */
}
+#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
+static MR_uint_least64_t
+parse_freq_from_x86_brand_string(char *string) {
+ unsigned int brand_string_len;
+ unsigned int i;
+ double multiplier;
+ int freq_index = -1;
+
+ brand_string_len = strlen(string);
+
+ /*
+ * There will be at least five characters if we can parse this, three
+ * for the '?Hz' suffix, at least one for the units, plus a space at
+ * the beginning o
+ */
+ if (!(brand_string_len > 5))
+ return 0;
+
+ if (!((string[brand_string_len - 1] == 'z') &&
+ (string[brand_string_len - 2] == 'H')))
+ return 0;
+
+ switch (string[brand_string_len - 3]) {
+ case 'M':
+ multiplier = 1000000.0;
+ break;
+ case 'G':
+ multiplier = 1000000000.0;
+ break;
+ case 'T':
+ /*
+ ** Yes, this is defined in the specification, Intel have some
+ ** strong ambitions regarding Moore's law. :-) We include it here to
+ ** conform with the standard.
+ */
+ multiplier = 1000000000000.0;
+ break;
+ default:
+ return 0;
+ }
+
+ /* Search for the beginning of the digits. */
+ for (i = brand_string_len - 4; i >= 0; i--) {
+ if (string[i] == ' ') {
+ freq_index = i+1;
+ break;
+ }
+ }
+ if (freq_index == -1) {
+ /* We didn't find the beginning of the frequency */
+ return 0;
+ }
+
+ /*
+ ** If strtod fails it returns zero, so if we fail to parse a number here,
+ ** we'll return zero which our caller understands as a parsing failure.
+ */
+ return (MR_uint_least64_t)(strtod(&string[freq_index], NULL) * multiplier);
+}
+#endif /* __GNUC__ && (__i386__ || __x86_64__) */
+
extern void
MR_profiling_start_timer(MR_Timer *timer) {
#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
Index: runtime/mercury_atomic_ops.h
===================================================================
RCS file: /home/mercury1/repository/mercury/runtime/mercury_atomic_ops.h,v
retrieving revision 1.6
diff -u -p -b -r1.6 mercury_atomic_ops.h
--- runtime/mercury_atomic_ops.h 5 Nov 2009 05:47:40 -0000 1.6
+++ runtime/mercury_atomic_ops.h 6 Nov 2009 05:09:50 -0000
@@ -344,6 +344,12 @@ typedef struct {
} MR_Timer;
/*
+** The number of CPU clock cycles per second, ie a 1GHz CPU will have a value
+** of 10^9, zero if unknown.
+*/
+extern MR_uint_least64_t MR_cpu_cycles_per_sec;
+
+/*
** Configure the profiling stats code. On i386 and x86_64 machines this uses
** CPUID to determine if the RDTSCP instruction is available and not prohibited
** by the OS.
Index: runtime/mercury_context.c
===================================================================
RCS file: /home/mercury1/repository/mercury/runtime/mercury_context.c,v
retrieving revision 1.69
diff -u -p -b -r1.69 mercury_context.c
--- runtime/mercury_context.c 5 Nov 2009 05:47:40 -0000 1.69
+++ runtime/mercury_context.c 6 Nov 2009 04:58:49 -0000
@@ -278,6 +278,11 @@ MR_write_out_profiling_parallel_executio
result = fprintf(file, "Mercury parallel execution profiling data\n\n");
if (result < 0) goto Error;
+ if (MR_cpu_cycles_per_sec) {
+ result = fprintf(file, "CPU cycles per second: %ld\n", MR_cpu_cycles_per_sec);
+ if (result < 0) goto Error;
+ }
+
result = fprint_stats(file, "MR_do_runnext(): global sparks executed",
&MR_profile_parallel_executed_global_sparks);
if (result < 0) goto Error;
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