The following changes since commit 5a90bb5f50f641a65f879ae09dbd65440e0ab2a6:
windowsaio: create a single completion port during init, associate files during open. (2012-12-06 21:06:28 +0100)
are available in the git repository at:
git://git.kernel.dk/fio.git master
Jens Axboe (1):
Add check for invariant TSC on x86 and use TSC is default clock if reliable
arch/arch-x86-common.h | 43 +++++++++++++++++++++++++++++++++++++++++++
arch/arch-x86.h | 2 ++
arch/arch-x86_64.h | 2 ++
crc/crc32c-intel.c | 16 ----------------
fio.c | 2 ++
fio.h | 1 +
gettime.c | 30 ++++++++++++++++++++++--------
options.c | 2 +-
8 files changed, 73 insertions(+), 25 deletions(-)
create mode 100644 arch/arch-x86-common.h
---
Diff of recent changes:
diff --git a/arch/arch-x86-common.h b/arch/arch-x86-common.h
new file mode 100644
index 0000000..1e62354
--- /dev/null
+++ b/arch/arch-x86-common.h
@@ -0,0 +1,43 @@
+#ifndef FIO_ARCH_X86_COMMON
+#define FIO_ARCH_X86_COMMON
+
+static inline void do_cpuid(unsigned int *eax, unsigned int *ebx,
+ unsigned int *ecx, unsigned int *edx)
+{
+ unsigned int id = *eax;
+
+ asm("movl %4, %%eax;"
+ "cpuid;"
+ "movl %%eax, %0;"
+ "movl %%ebx, %1;"
+ "movl %%ecx, %2;"
+ "movl %%edx, %3;"
+ : "=r" (*eax), "=r" (*ebx), "=r" (*ecx), "=r" (*edx)
+ : "r" (id)
+ : "eax", "ebx", "ecx", "edx");
+}
+
+#define ARCH_HAVE_INIT
+extern int tsc_reliable;
+static inline int arch_init(char *envp[])
+{
+ unsigned int eax, ebx, ecx, edx;
+
+ /*
+ * Check for TSC
+ */
+ eax = 1;
+ do_cpuid(&eax, &ebx, &ecx, &edx);
+ if (!(edx & (1U << 4)))
+ return 0;
+
+ /*
+ * Check for constant rate and synced (across cores) TSC
+ */
+ eax = 0x80000007;
+ do_cpuid(&eax, &ebx, &ecx, &edx);
+ tsc_reliable = edx & (1U << 8);
+ return 0;
+}
+
+#endif
diff --git a/arch/arch-x86.h b/arch/arch-x86.h
index 1ededd8..4803006 100644
--- a/arch/arch-x86.h
+++ b/arch/arch-x86.h
@@ -1,6 +1,8 @@
#ifndef ARCH_X86_H
#define ARCH_X86_H
+#include "arch-x86-common.h"
+
#define FIO_ARCH (arch_i386)
#ifndef __NR_ioprio_set
diff --git a/arch/arch-x86_64.h b/arch/arch-x86_64.h
index 29e681f..d8b0933 100644
--- a/arch/arch-x86_64.h
+++ b/arch/arch-x86_64.h
@@ -1,6 +1,8 @@
#ifndef ARCH_X86_64_h
#define ARCH_X86_64_h
+#include "arch-x86-common.h"
+
#define FIO_ARCH (arch_x86_64)
#ifndef __NR_ioprio_set
diff --git a/crc/crc32c-intel.c b/crc/crc32c-intel.c
index 8a6e6dc..8e1cd58 100644
--- a/crc/crc32c-intel.c
+++ b/crc/crc32c-intel.c
@@ -78,22 +78,6 @@ uint32_t crc32c_intel(unsigned char const *data, unsigned long length)
return crc;
}
-static void do_cpuid(unsigned int *eax, unsigned int *ebx, unsigned int *ecx,
- unsigned int *edx)
-{
- int id = *eax;
-
- asm("movl %4, %%eax;"
- "cpuid;"
- "movl %%eax, %0;"
- "movl %%ebx, %1;"
- "movl %%ecx, %2;"
- "movl %%edx, %3;"
- : "=r" (*eax), "=r" (*ebx), "=r" (*ecx), "=r" (*edx)
- : "r" (id)
- : "eax", "ebx", "ecx", "edx");
-}
-
void crc32c_intel_probe(void)
{
if (!crc32c_probed) {
diff --git a/fio.c b/fio.c
index ac026fb..f44273f 100644
--- a/fio.c
+++ b/fio.c
@@ -104,6 +104,8 @@ int main(int argc, char *argv[], char *envp[])
if (parse_options(argc, argv))
return 1;
+ fio_time_init();
+
if (nr_clients)
return fio_handle_clients();
else
diff --git a/fio.h b/fio.h
index 3de3f00..de4ca4d 100644
--- a/fio.h
+++ b/fio.h
@@ -598,6 +598,7 @@ extern char *job_section;
extern int fio_gtod_offload;
extern int fio_gtod_cpu;
extern enum fio_cs fio_clock_source;
+extern int fio_clock_source_set;
extern int warnings_fatal;
extern int terse_version;
extern int is_backend;
diff --git a/gettime.c b/gettime.c
index 35d685e..89a3a01 100644
--- a/gettime.c
+++ b/gettime.c
@@ -15,11 +15,13 @@
#ifdef ARCH_HAVE_CPU_CLOCK
static unsigned long cycles_per_usec;
static unsigned long last_cycles;
+int tsc_reliable = 0;
#endif
static struct timeval last_tv;
static int last_tv_valid;
enum fio_cs fio_clock_source = FIO_PREFERRED_CLOCK_SOURCE;
+int fio_clock_source_set = 0;
#ifdef FIO_DEBUG_TIME
@@ -208,15 +210,17 @@ static unsigned long get_cycles_per_usec(void)
return c_e - c_s;
}
+#define NR_TIME_ITERS 50
+
static void calibrate_cpu_clock(void)
{
double delta, mean, S;
- unsigned long avg, cycles[10];
+ unsigned long avg, cycles[NR_TIME_ITERS];
int i, samples;
cycles[0] = get_cycles_per_usec();
S = delta = mean = 0.0;
- for (i = 0; i < 10; i++) {
+ for (i = 0; i < NR_TIME_ITERS; i++) {
cycles[i] = get_cycles_per_usec();
delta = cycles[i] - mean;
if (delta) {
@@ -225,10 +229,10 @@ static void calibrate_cpu_clock(void)
}
}
- S = sqrt(S / (10 - 1.0));
+ S = sqrt(S / (NR_TIME_ITERS - 1.0));
samples = avg = 0;
- for (i = 0; i < 10; i++) {
+ for (i = 0; i < NR_TIME_ITERS; i++) {
double this = cycles[i];
if ((fmax(this, mean) - fmin(this, mean)) > S)
@@ -237,10 +241,10 @@ static void calibrate_cpu_clock(void)
avg += this;
}
- S /= 10.0;
- mean /= 10.0;
+ S /= (double) NR_TIME_ITERS;
+ mean /= (double) NR_TIME_ITERS;
- for (i = 0; i < 10; i++)
+ for (i = 0; i < NR_TIME_ITERS; i++)
dprint(FD_TIME, "cycles[%d]=%lu\n", i, cycles[i] / 10);
avg /= (samples * 10);
@@ -248,7 +252,6 @@ static void calibrate_cpu_clock(void)
dprint(FD_TIME, "mean=%f, S=%f\n", mean, S);
cycles_per_usec = avg;
-
}
#else
static void calibrate_cpu_clock(void)
@@ -260,6 +263,17 @@ void fio_clock_init(void)
{
last_tv_valid = 0;
calibrate_cpu_clock();
+
+ /*
+ * If the arch sets tsc_reliable != 0, then it must be good enough
+ * to use as THE clock source. For x86 CPUs, this means the TSC
+ * runs at a constant rate and is synced across CPU cores.
+ */
+ if (tsc_reliable) {
+ if (!fio_clock_source_set)
+ fio_clock_source = CS_CPUCLOCK;
+ } else if (fio_clock_source == CS_CPUCLOCK)
+ log_info("fio: clocksource=cpu may not be reliable\n");
}
unsigned long long utime_since(struct timeval *s, struct timeval *e)
diff --git a/options.c b/options.c
index d46bcbb..738c78b 100644
--- a/options.c
+++ b/options.c
@@ -370,7 +370,7 @@ static int fio_clock_source_cb(void *data, const char *str)
struct thread_data *td = data;
fio_clock_source = td->o.clocksource;
- fio_time_init();
+ fio_clock_source_set = 1;
return 0;
}
--
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