Recent changes (master)

[Jens Axboe <jaxboe@xxxxxxxxxxxx>]

The following changes since commit fa80feae51331fb170e784459fa1359d7ec3a963:

  Add check for invariant TSC on x86 and use TSC is default clock if reliable (2012-12-09 20:29:00 +0100)

are available in the git repository at:
  git://git.kernel.dk/fio.git master

Jens Axboe (6):
      Increase CPU clock calibration accuracy
      gettime: calibration rounding error
      gettime: fix CPU calibration reported mean
      Define TSC arch_init() for PPC and IA64
      cpu clock: round up when dividing by samples
      Merge branch 'master' of ssh://brick.kernel.dk/data/git/fio

 arch/arch-ia64.h |    7 +++++++
 arch/arch-ppc.h  |    7 +++++++
 gettime.c        |    9 +++++----
 3 files changed, 19 insertions(+), 4 deletions(-)

---

Diff of recent changes:

diff --git a/arch/arch-ia64.h b/arch/arch-ia64.h
index f4464c4..8ccbd86 100644
--- a/arch/arch-ia64.h
+++ b/arch/arch-ia64.h
@@ -42,6 +42,13 @@ static inline unsigned long get_cpu_clock(void)
 	return ret;
 }
 
+#define ARCH_HAVE_INIT
+extern int tsc_reliable;
+static inline int arch_init(char *envp[])
+{
+	tsc_reliable = 1;
+}
+
 #define ARCH_HAVE_FFZ
 #define ARCH_HAVE_CPU_CLOCK
 
diff --git a/arch/arch-ppc.h b/arch/arch-ppc.h
index b790a55..0f20375 100644
--- a/arch/arch-ppc.h
+++ b/arch/arch-ppc.h
@@ -58,6 +58,13 @@ static inline unsigned long long get_cpu_clock(void)
 	return ret;
 }
 
+#define ARCH_HAVE_INIT
+extern int tsc_reliable;
+static inline int arch_init(char *envp[])
+{
+	tsc_reliable = 1;
+}
+
 #define ARCH_HAVE_FFZ
 #define ARCH_HAVE_CPU_CLOCK
 
diff --git a/gettime.c b/gettime.c
index 89a3a01..1ba18e9 100644
--- a/gettime.c
+++ b/gettime.c
@@ -201,13 +201,13 @@ static unsigned long get_cycles_per_usec(void)
 
 		gettimeofday(&e, NULL);
 		elapsed = utime_since(&s, &e);
-		if (elapsed >= 10) {
+		if (elapsed >= 1280) {
 			c_e = get_cpu_clock();
 			break;
 		}
 	} while (1);
 
-	return c_e - c_s;
+	return (c_e - c_s + 127) >> 7;
 }
 
 #define NR_TIME_ITERS	50
@@ -242,12 +242,13 @@ static void calibrate_cpu_clock(void)
 	}
 
 	S /= (double) NR_TIME_ITERS;
-	mean /= (double) NR_TIME_ITERS;
+	mean /= 10.0;
 
 	for (i = 0; i < NR_TIME_ITERS; i++)
 		dprint(FD_TIME, "cycles[%d]=%lu\n", i, cycles[i] / 10);
 
-	avg /= (samples * 10);
+	avg /= samples;
+	avg = (avg + 9) / 10;
 	dprint(FD_TIME, "avg: %lu\n", avg);
 	dprint(FD_TIME, "mean=%f, S=%f\n", mean, S);
 
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