[PATCH 5/6] tests: Move busy loop to test support
Sebastian Huber
sebastian.huber at embedded-brains.de
Thu Jun 29 13:23:17 UTC 2017
Update #3056.
---
cpukit/libmisc/Makefile.am | 1 +
cpukit/libmisc/testsupport/test.h | 18 +++-
cpukit/libmisc/testsupport/testbusy.c | 107 +++++++++++++++++++++
.../sptests/spintrcritical_support/intrcritical.c | 96 ++----------------
4 files changed, 135 insertions(+), 87 deletions(-)
create mode 100644 cpukit/libmisc/testsupport/testbusy.c
diff --git a/cpukit/libmisc/Makefile.am b/cpukit/libmisc/Makefile.am
index d8fa47a2a5..6772dd1673 100644
--- a/cpukit/libmisc/Makefile.am
+++ b/cpukit/libmisc/Makefile.am
@@ -174,6 +174,7 @@ libstringto_a_SOURCES = stringto/stringtodouble.c stringto/stringtofloat.c \
noinst_LIBRARIES += libtestsupport.a
libtestsupport_a_SOURCES =
libtestsupport_a_SOURCES += testsupport/testbeginend.c
+libtestsupport_a_SOURCES += testsupport/testbusy.c
libtestsupport_a_SOURCES += testsupport/testextension.c
libtestsupport_a_SOURCES += testsupport/testparallel.c
diff --git a/cpukit/libmisc/testsupport/test.h b/cpukit/libmisc/testsupport/test.h
index a32e2c42c1..d9ac6caf91 100644
--- a/cpukit/libmisc/testsupport/test.h
+++ b/cpukit/libmisc/testsupport/test.h
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2014, 2016 embedded brains GmbH. All rights reserved.
+ * Copyright (c) 2014, 2017 embedded brains GmbH. All rights reserved.
*
* embedded brains GmbH
* Dornierstr. 4
@@ -260,6 +260,22 @@ void rtems_test_parallel(
size_t job_count
);
+/**
+ * @brief Performs a busy loop with the specified iteration count.
+ *
+ * This function is optimized to not perform memory accesses and should have a
+ * small jitter.
+ *
+ * @param[in] count The iteration count.
+ */
+void rtems_test_busy(uint_fast32_t count);
+
+/**
+ * @brief Returns a count value for rtems_test_busy() which yields roughly a
+ * duration of one clock tick.
+ */
+uint_fast32_t rtems_test_get_one_tick_busy_count(void);
+
/** @} */
#ifdef __cplusplus
diff --git a/cpukit/libmisc/testsupport/testbusy.c b/cpukit/libmisc/testsupport/testbusy.c
new file mode 100644
index 0000000000..2d34a805dc
--- /dev/null
+++ b/cpukit/libmisc/testsupport/testbusy.c
@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2014, 2017 embedded brains GmbH. All rights reserved.
+ *
+ * embedded brains GmbH
+ * Dornierstr. 4
+ * 82178 Puchheim
+ * Germany
+ * <rtems at embedded-brains.de>
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.org/license/LICENSE.
+ */
+
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/test.h>
+#include <rtems.h>
+
+static uint_fast32_t estimate_busy_loop_maximum( void )
+{
+ uint_fast32_t units = 0;
+ uint_fast32_t initial = rtems_clock_get_ticks_since_boot();
+
+ while ( initial == rtems_clock_get_ticks_since_boot() ) {
+ ++units;
+ }
+
+ return units;
+}
+
+static uint_fast32_t wait_for_tick_change( void )
+{
+ uint_fast32_t initial = rtems_clock_get_ticks_since_boot();
+ uint_fast32_t now;
+
+ do {
+ now = rtems_clock_get_ticks_since_boot();
+ } while ( now == initial );
+
+ return now;
+}
+
+/*
+ * It is important that we use actually use the same rtems_test_busy() function
+ * at the various places, since otherwise the obtained maximum value might be
+ * wrong. So, the compiler must not inline this function.
+ */
+RTEMS_NO_INLINE void rtems_test_busy( uint_fast32_t count )
+{
+ uint_fast32_t i = 0;
+
+ do {
+ __asm__ volatile ("");
+ ++i;
+ } while ( i < count );
+}
+
+uint_fast32_t rtems_test_get_one_tick_busy_count( void )
+{
+ uint_fast32_t last;
+ uint_fast32_t now;
+ uint_fast32_t a;
+ uint_fast32_t b;
+ uint_fast32_t m;
+
+ /* Choose a lower bound */
+ a = 1;
+
+ /* Estimate an upper bound */
+
+ wait_for_tick_change();
+ b = 2 * estimate_busy_loop_maximum();
+
+ while ( true ) {
+ last = wait_for_tick_change();
+ rtems_test_busy( b );
+ now = rtems_clock_get_ticks_since_boot();
+
+ if ( now != last ) {
+ break;
+ }
+
+ b *= 2;
+ last = now;
+ }
+
+ /* Find a good value */
+ do {
+ m = ( a + b ) / 2;
+
+ last = wait_for_tick_change();
+ rtems_test_busy( m );
+ now = rtems_clock_get_ticks_since_boot();
+
+ if ( now != last ) {
+ b = m;
+ } else {
+ a = m;
+ }
+ } while ( b - a > 1 );
+
+ return m;
+}
diff --git a/testsuites/sptests/spintrcritical_support/intrcritical.c b/testsuites/sptests/spintrcritical_support/intrcritical.c
index a9fcdd2a37..51ab42f5d6 100644
--- a/testsuites/sptests/spintrcritical_support/intrcritical.c
+++ b/testsuites/sptests/spintrcritical_support/intrcritical.c
@@ -17,9 +17,9 @@
#define INTERRUPT_CRITICAL_NAME rtems_build_name( 'I', 'C', 'R', 'I' )
typedef struct {
- rtems_interval minimum;
- rtems_interval maximum;
- rtems_interval maximum_current;
+ uint_fast32_t minimum;
+ uint_fast32_t maximum;
+ uint_fast32_t maximum_current;
rtems_timer_service_routine_entry tsr;
rtems_id timer;
uint64_t t0;
@@ -28,19 +28,7 @@ typedef struct {
static interrupt_critical_control interrupt_critical;
-static rtems_interval estimate_busy_loop_maximum( void )
-{
- rtems_interval units = 0;
- rtems_interval initial = rtems_clock_get_ticks_since_boot();
-
- while ( initial == rtems_clock_get_ticks_since_boot() ) {
- ++units;
- }
-
- return units;
-}
-
-static rtems_interval wait_for_tick_change( void )
+static void wait_for_tick_change( void )
{
rtems_interval initial = rtems_clock_get_ticks_since_boot();
rtems_interval now;
@@ -48,75 +36,11 @@ static rtems_interval wait_for_tick_change( void )
do {
now = rtems_clock_get_ticks_since_boot();
} while ( now == initial );
-
- return now;
-}
-
-/*
- * It is important that we use actually use the same busy() function at the
- * various places, since otherwise the obtained maximum value might be wrong.
- * So the compiler must not inline this function.
- */
-static __attribute__( ( noinline ) ) void busy( rtems_interval max )
-{
- rtems_interval i = 0;
-
- do {
- __asm__ volatile ("");
- ++i;
- } while ( i < max );
-}
-
-static rtems_interval get_one_tick_busy_value( void )
-{
- rtems_interval last;
- rtems_interval now;
- rtems_interval a;
- rtems_interval b;
- rtems_interval m;
-
- /* Choose a lower bound */
- a = 1;
-
- /* Estimate an upper bound */
-
- wait_for_tick_change();
- b = 2 * estimate_busy_loop_maximum();
-
- while ( true ) {
- last = wait_for_tick_change();
- busy( b );
- now = rtems_clock_get_ticks_since_boot();
-
- if ( now != last ) {
- break;
- }
-
- b *= 2;
- last = now;
- }
-
- /* Find a good value */
- do {
- m = ( a + b ) / 2;
-
- last = wait_for_tick_change();
- busy( m );
- now = rtems_clock_get_ticks_since_boot();
-
- if ( now != last ) {
- b = m;
- } else {
- a = m;
- }
- } while ( b - a > 1 );
-
- return m;
}
static bool interrupt_critical_busy_wait( void )
{
- rtems_interval max = interrupt_critical.maximum_current;
+ uint_fast32_t max = interrupt_critical.maximum_current;
bool reset = max <= interrupt_critical.minimum;
if ( reset ) {
@@ -125,7 +49,7 @@ static bool interrupt_critical_busy_wait( void )
interrupt_critical.maximum_current = max - 1;
}
- busy( max );
+ rtems_test_busy( max );
return reset;
}
@@ -134,7 +58,7 @@ void interrupt_critical_section_test_support_initialize(
rtems_timer_service_routine_entry tsr
)
{
- rtems_interval m;
+ uint_fast32_t m;
interrupt_critical.tsr = tsr;
@@ -146,7 +70,7 @@ void interrupt_critical_section_test_support_initialize(
rtems_test_assert( sc == RTEMS_SUCCESSFUL );
}
- m = get_one_tick_busy_value();
+ m = rtems_test_get_one_tick_busy_count();
interrupt_critical.minimum = 0;
interrupt_critical.maximum = m;
@@ -197,7 +121,7 @@ bool interrupt_critical_section_test(
rtems_status_code sc;
rtems_id id;
uint64_t delta;
- rtems_interval busy_delta;
+ uint_fast32_t busy_delta;
int retries = 3;
interrupt_critical_section_test_support_initialize( tsr );
@@ -222,7 +146,7 @@ bool interrupt_critical_section_test(
/* Update minimum */
delta = interrupt_critical.t1 - interrupt_critical.t0;
- busy_delta = (rtems_interval)
+ busy_delta = (uint_fast32_t)
( ( interrupt_critical.maximum * ( 2 * delta ) )
/ rtems_configuration_get_nanoseconds_per_tick() );
--
2.12.3
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