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authorTavian Barnes <tavianator@gmail.com>2009-09-17 13:33:06 +0000
committerTavian Barnes <tavianator@gmail.com>2009-09-17 13:33:06 +0000
commit9a358c3cdf8eb34754cc5544e2a5e0f67c022f8d (patch)
treea351b5a08f614e3ceeb7f63c7cf68f68377e54c5
parenta9f27bf33c6b6b6e9aac0eb1e69743120a11daa1 (diff)
downloadlibsandglass-9a358c3cdf8eb34754cc5544e2a5e0f67c022f8d.tar.xz
Improve sandglass_tsc_resolution(), and fix timespec-based grains counts.
-rw-r--r--src/Makefile.am6
-rw-r--r--src/sandglass.c9
-rw-r--r--src/sandglass_impl.h3
-rw-r--r--src/timespec.c30
-rw-r--r--src/tsc.c35
5 files changed, 74 insertions, 9 deletions
diff --git a/src/Makefile.am b/src/Makefile.am
index 476c855..519e0ea 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -21,7 +21,11 @@ lib_LTLIBRARIES = libsandglass.la
nobase_include_HEADERS = sandglass.h
-libsandglass_la_SOURCES = sandglass.h sandglass_impl.h sandglass.c tsc.c
+libsandglass_la_SOURCES = sandglass.h \
+ sandglass_impl.h \
+ sandglass.c \
+ timespec.c \
+ tsc.c
if X86
libsandglass_la_SOURCES += x86/tsc-x86.s
diff --git a/src/sandglass.c b/src/sandglass.c
index 57729f9..3399b73 100644
--- a/src/sandglass.c
+++ b/src/sandglass.c
@@ -184,6 +184,9 @@ sandglass_elapse(sandglass_t *sandglass)
return -1;
sandglass->grains -= oldgrains;
+ /* Magical correction for timespec-based grains */
+ if (sandglass->grains < 0)
+ sandglass->grains += 2000000000L;
sandglass->grains /= sandglass->loops;
return 0;
@@ -219,12 +222,11 @@ sandglass_real_gettime(sandglass_t *sandglass)
if (sysconf(_SC_MONOTONIC_CLOCK) > 0) {
if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
return -1;
- sandglass->grains = ts.tv_nsec;
} else {
if (clock_gettime(CLOCK_REALTIME, &ts) != 0)
return -1;
- sandglass->grains = ts.tv_nsec;
}
+ sandglass->grains = sandglass_timespec_grains(&ts);
break;
default:
@@ -242,13 +244,12 @@ sandglass_real_gettime(sandglass_t *sandglass)
if (sysconf(_SC_THREAD_CPUTIME) > 0) {
if (clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts) != 0)
return -1;
- sandglass->grains = ts.tv_nsec;
} else if (sysconf(_SC_CPUTIME) > 0) {
if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts) != 0)
return -1;
- sandglass->grains = ts.tv_nsec;
} else
return -1;
+ sandglass->grains = sandglass_timespec_grains(&ts);
break;
case SANDGLASS_SYSTEM:
diff --git a/src/sandglass_impl.h b/src/sandglass_impl.h
index 5a3650e..b618a93 100644
--- a/src/sandglass_impl.h
+++ b/src/sandglass_impl.h
@@ -26,6 +26,7 @@
#define SANDGLASS_IMPL_H_INCLUDED
#include "sandglass.h"
+#include <time.h>
#ifdef SANDGLASS_TSC
/* Read the time stamp counter */
@@ -36,4 +37,6 @@ double sandglass_tsc_resolution();
unsigned int sandglass_tsc_loops();
#endif
+long sandglass_timespec_grains(const struct timespec *ts);
+
#endif /* SANDGLASS_IMPL_H_INCLUDED */ \ No newline at end of file
diff --git a/src/timespec.c b/src/timespec.c
new file mode 100644
index 0000000..81a5815
--- /dev/null
+++ b/src/timespec.c
@@ -0,0 +1,30 @@
+/*************************************************************************
+ * Copyright (C) 2008 Tavian Barnes <tavianator@gmail.com> *
+ * *
+ * This file is part of The Sandglass Library. *
+ * *
+ * The Sandglass Library is free software; you can redistribute it *
+ * and/or modify it under the terms of the GNU Lesser General Public *
+ * License as published by the Free Software Foundation; either version *
+ * 3 of the License, or (at your option) any later version. *
+ * *
+ * The Sandglass Library is distributed in the hope that it will be *
+ * useful, but WITHOUT ANY WARRANTY; without even the implied warranty *
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
+ * Lesser General Public License for more details. *
+ * *
+ * You should have received a copy of the GNU Lesser General Public *
+ * License along with this program. If not, see *
+ * <http://www.gnu.org/licenses/>. *
+ *************************************************************************/
+
+#include "sandglass_impl.h"
+#include "sandglass.h"
+#include <time.h>
+
+/* Convert a timespec to grains */
+long
+sandglass_timespec_grains(const struct timespec *ts)
+{
+ return (ts->tv_sec%2L)*1000000000L + ts->tv_nsec;
+} \ No newline at end of file
diff --git a/src/tsc.c b/src/tsc.c
index 64fe1b1..8038c0e 100644
--- a/src/tsc.c
+++ b/src/tsc.c
@@ -21,19 +21,46 @@
#include "sandglass_impl.h"
#include "sandglass.h"
#include <time.h>
+#include <unistd.h>
/* Gets the number of clock ticks per second */
double
sandglass_tsc_resolution()
{
- static long tsc = 0;
- struct timespec ts = { .tv_sec = 0, .tv_nsec = 100000000 };
+ static long tsc = 0, grains1, grains2;
+
+ int monotonic;
+ struct timespec ts;
if (tsc == 0) {
+ monotonic = sysconf(_SC_MONOTONIC_CLOCK) > 0;
+ if (monotonic) {
+ if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
+ return 0.0/0.0;
+ } else {
+ if (clock_gettime(CLOCK_REALTIME, &ts) != 0)
+ return 0.0/0.0;
+ }
tsc = sandglass_get_tsc();
- while (nanosleep(&ts, &ts) != 0);
+ grains1 = sandglass_timespec_grains(&ts);
+ grains2 = grains1;
+
+ while (((grains2 >= grains1) ? grains2 - grains1
+ : 2000000000L + (grains2 - grains1))
+ < 10000000L)
+ {
+ if (monotonic) {
+ if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
+ return 0.0/0.0;
+ } else {
+ if (clock_gettime(CLOCK_REALTIME, &ts) != 0)
+ return 0.0/0.0;
+ }
+ grains2 = sandglass_timespec_grains(&ts);
+ }
+
tsc = sandglass_get_tsc() - tsc;
}
- return tsc*10.0;
+ return tsc*1.0e9/(grains2 - grains1);
}