[rtems commit] score: Add an SMP sequence lock implementation
Sebastian Huber
sebh at rtems.org
Thu Jun 9 08:49:38 UTC 2016
Module: rtems
Branch: master
Commit: 05b7eec276a130cde39fed861ad4a9d1f01e876c
Changeset: http://git.rtems.org/rtems/commit/?id=05b7eec276a130cde39fed861ad4a9d1f01e876c
Author: Sebastian Huber <sebastian.huber at embedded-brains.de>
Date: Wed Jun 8 15:18:14 2016 +0200
score: Add an SMP sequence lock implementation
---
cpukit/score/Makefile.am | 1 +
cpukit/score/include/rtems/score/smplockseq.h | 173 +++++++++++++++
cpukit/score/preinstall.am | 4 +
testsuites/smptests/smplock01/init.c | 60 ++++-
testsuites/smptests/smplock01/smplock01.scn | 306 ++++++++++++++++++++++++--
5 files changed, 520 insertions(+), 24 deletions(-)
diff --git a/cpukit/score/Makefile.am b/cpukit/score/Makefile.am
index 29e822d..537cf60 100644
--- a/cpukit/score/Makefile.am
+++ b/cpukit/score/Makefile.am
@@ -82,6 +82,7 @@ include_rtems_score_HEADERS += include/rtems/score/schedulersmpimpl.h
include_rtems_score_HEADERS += include/rtems/score/smp.h
include_rtems_score_HEADERS += include/rtems/score/smpbarrier.h
include_rtems_score_HEADERS += include/rtems/score/smplock.h
+include_rtems_score_HEADERS += include/rtems/score/smplockseq.h
include_rtems_score_HEADERS += include/rtems/score/smpimpl.h
include_rtems_score_HEADERS += include/rtems/score/stack.h
include_rtems_score_HEADERS += include/rtems/score/stackimpl.h
diff --git a/cpukit/score/include/rtems/score/smplockseq.h b/cpukit/score/include/rtems/score/smplockseq.h
new file mode 100644
index 0000000..6fe7b7a
--- /dev/null
+++ b/cpukit/score/include/rtems/score/smplockseq.h
@@ -0,0 +1,173 @@
+/**
+ * @file
+ *
+ * @ingroup ScoreSMPLock
+ *
+ * @brief SMP Lock API
+ */
+
+/*
+ * Copyright (c) 2016 embedded brains GmbH
+ *
+ * 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.
+ */
+
+#ifndef _RTEMS_SCORE_SMPLOCKSEQ_H
+#define _RTEMS_SCORE_SMPLOCKSEQ_H
+
+#include <rtems/score/cpuopts.h>
+
+#if defined(RTEMS_SMP)
+
+#include <rtems/score/atomic.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+/**
+ * @addtogroup ScoreSMPLock
+ *
+ * @{
+ */
+
+/**
+ * @brief SMP sequence lock control.
+ *
+ * The sequence lock offers a consistent data set for readers in the presence
+ * of at most one concurrent writer. Due to the read-modify-write operation in
+ * _SMP_sequence_lock_Read_retry() the data corresponding to the last written
+ * sequence number is observed. To allow multiple writers an additional SMP
+ * lock is necessary to serialize writes.
+ *
+ * See also Hans-J. Boehm, HP Laboratories,
+ * "Can Seqlocks Get Along With Programming Language Memory Models?",
+ * http://www.hpl.hp.com/techreports/2012/HPL-2012-68.pdf
+ */
+typedef struct {
+ /**
+ * @brief The sequence number.
+ *
+ * An odd value indicates that a write is in progress.
+ */
+ Atomic_Uint sequence;
+} SMP_sequence_lock_Control;
+
+/**
+ * @brief SMP sequence lock control initializer for static initialization.
+ */
+#define SMP_SEQUENCE_LOCK_INITIALIZER { ATOMIC_INITIALIZER_UINT( 0 ) }
+
+/**
+ * @brief Initializes an SMP sequence lock.
+ *
+ * Concurrent initialization leads to unpredictable results.
+ *
+ * @param lock The SMP sequence lock control.
+ */
+static inline void _SMP_sequence_lock_Initialize( SMP_sequence_lock_Control *lock )
+{
+ _Atomic_Init_uint( &lock->sequence, 0 );
+}
+
+/**
+ * @brief Destroys an SMP sequence lock.
+ *
+ * Concurrent destruction leads to unpredictable results.
+ *
+ * @param lock The SMP sequence lock control.
+ */
+static inline void _SMP_sequence_lock_Destroy( SMP_sequence_lock_Control *lock )
+{
+ (void) lock;
+}
+
+/**
+ * @brief Begins an SMP sequence lock write operation.
+ *
+ * This function will not disable interrupts. The caller must ensure that the
+ * current thread of execution is not interrupted indefinite since this would
+ * starve readers.
+ *
+ * @param lock The SMP sequence lock control.
+ *
+ * @return The current sequence number.
+ */
+static inline unsigned int _SMP_sequence_lock_Write_begin(
+ SMP_sequence_lock_Control *lock
+)
+{
+ unsigned int seq;
+
+ seq = _Atomic_Load_uint( &lock->sequence, ATOMIC_ORDER_RELAXED );
+ _Atomic_Store_uint( &lock->sequence, seq + 1, ATOMIC_ORDER_RELAXED );
+
+ /* There is no atomic store with acquire/release semantics */
+ _Atomic_Fence( ATOMIC_ORDER_ACQ_REL );
+
+ return seq;
+}
+
+/**
+ * @brief Ends an SMP sequence lock write operation.
+ *
+ * @param lock The SMP sequence lock control.
+ * @param seq The sequence number returned by _SMP_sequence_lock_Write_begin().
+ */
+static inline void _SMP_sequence_lock_Write_end(
+ SMP_sequence_lock_Control *lock,
+ unsigned int seq
+)
+{
+ _Atomic_Store_uint( &lock->sequence, seq + 2, ATOMIC_ORDER_RELEASE );
+}
+
+/**
+ * @brief Begins an SMP sequence lock read operation.
+ *
+ * This function will not disable interrupts.
+ *
+ * @param lock The SMP sequence lock control.
+ *
+ * @return The current sequence number.
+ */
+static inline unsigned int _SMP_sequence_lock_Read_begin(
+ const SMP_sequence_lock_Control *lock
+)
+{
+ return _Atomic_Load_uint( &lock->sequence, ATOMIC_ORDER_ACQUIRE );
+}
+
+/**
+ * @brief Ends an SMP sequence lock read operation and indicates if a retry is
+ * necessary.
+ *
+ * @param lock The SMP sequence lock control.
+ * @param seq The sequence number returned by _SMP_sequence_lock_Read_begin().
+ *
+ * @retval true The read operation must be retried with a call to
+ * _SMP_sequence_lock_Read_begin().
+ * @retval false Otherwise.
+ */
+static inline bool _SMP_sequence_lock_Read_retry(
+ SMP_sequence_lock_Control *lock,
+ unsigned int seq
+)
+{
+ unsigned int seq2;
+
+ seq2 = _Atomic_Fetch_add_uint( &lock->sequence, 0, ATOMIC_ORDER_RELEASE );
+ return seq != seq2 || seq % 2 != 0;
+}
+
+/**@}*/
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+#endif /* RTEMS_SMP */
+
+#endif /* _RTEMS_SCORE_SMPLOCKSEQ_H */
diff --git a/cpukit/score/preinstall.am b/cpukit/score/preinstall.am
index 2ed07b9..1ba332d 100644
--- a/cpukit/score/preinstall.am
+++ b/cpukit/score/preinstall.am
@@ -296,6 +296,10 @@ $(PROJECT_INCLUDE)/rtems/score/smplock.h: include/rtems/score/smplock.h $(PROJEC
$(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/smplock.h
PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/smplock.h
+$(PROJECT_INCLUDE)/rtems/score/smplockseq.h: include/rtems/score/smplockseq.h $(PROJECT_INCLUDE)/rtems/score/$(dirstamp)
+ $(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/smplockseq.h
+PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/smplockseq.h
+
$(PROJECT_INCLUDE)/rtems/score/smpimpl.h: include/rtems/score/smpimpl.h $(PROJECT_INCLUDE)/rtems/score/$(dirstamp)
$(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/smpimpl.h
PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/smpimpl.h
diff --git a/testsuites/smptests/smplock01/init.c b/testsuites/smptests/smplock01/init.c
index 5eeb1ca..62397a3 100644
--- a/testsuites/smptests/smplock01/init.c
+++ b/testsuites/smptests/smplock01/init.c
@@ -18,6 +18,7 @@
#include <rtems/score/smplock.h>
#include <rtems/score/smplockmcs.h>
+#include <rtems/score/smplockseq.h>
#include <rtems/score/smpbarrier.h>
#include <rtems/score/atomic.h>
#include <rtems.h>
@@ -30,7 +31,7 @@ const char rtems_test_name[] = "SMPLOCK 1";
#define CPU_COUNT 32
-#define TEST_COUNT 10
+#define TEST_COUNT 11
typedef enum {
INITIAL,
@@ -50,6 +51,11 @@ typedef struct {
SMP_lock_Stats mcs_stats;
#endif
SMP_MCS_lock_Control mcs_lock;
+ SMP_sequence_lock_Control seq_lock;
+ char unused_space_for_cache_line_separation_0[128];
+ int a;
+ char unused_space_for_cache_line_separation_1[128];
+ int b;
} global_context;
static global_context context = {
@@ -59,7 +65,8 @@ static global_context context = {
#if defined(RTEMS_PROFILING)
.mcs_stats = SMP_LOCK_STATS_INITIALIZER("global MCS"),
#endif
- .mcs_lock = SMP_MCS_LOCK_INITIALIZER
+ .mcs_lock = SMP_MCS_LOCK_INITIALIZER,
+ .seq_lock = SMP_SEQUENCE_LOCK_INITIALIZER
};
static const char * const test_names[TEST_COUNT] = {
@@ -72,7 +79,8 @@ static const char * const test_names[TEST_COUNT] = {
"local ticket lock with global counter",
"local MCS lock with global counter",
"global ticket lock with busy section",
- "global MCS lock with busy section"
+ "global MCS lock with busy section",
+ "sequence lock"
};
static void stop_test_timer(rtems_id timer_id, void *arg)
@@ -355,6 +363,49 @@ static void test_9_body(
ctx->test_counter[test][cpu_self] = counter;
}
+static void test_10_body(
+ int test,
+ global_context *ctx,
+ SMP_barrier_State *bs,
+ unsigned int cpu_count,
+ unsigned int cpu_self
+)
+{
+ unsigned long counter = 0;
+ unsigned long seq;
+
+ if (cpu_self == 0) {
+ while (assert_state(ctx, START_TEST)) {
+ seq = _SMP_sequence_lock_Write_begin(&ctx->seq_lock);
+
+ ctx->a = counter;
+ ctx->b = counter;
+
+ _SMP_sequence_lock_Write_end(&ctx->seq_lock, seq);
+
+ ++counter;
+ }
+ } else {
+ while (assert_state(ctx, START_TEST)) {
+ unsigned long a;
+ unsigned long b;
+
+ do {
+ seq = _SMP_sequence_lock_Read_begin(&ctx->seq_lock);
+
+ a = ctx->a;
+ b = ctx->b;
+
+ } while (_SMP_sequence_lock_Read_retry(&ctx->seq_lock, seq));
+
+ ++counter;
+ rtems_test_assert(a == b);
+ }
+ }
+
+ ctx->test_counter[test][cpu_self] = counter;
+}
+
static const test_body test_bodies[TEST_COUNT] = {
test_0_body,
test_1_body,
@@ -365,7 +416,8 @@ static const test_body test_bodies[TEST_COUNT] = {
test_6_body,
test_7_body,
test_8_body,
- test_9_body
+ test_9_body,
+ test_10_body
};
static void run_tests(
diff --git a/testsuites/smptests/smplock01/smplock01.scn b/testsuites/smptests/smplock01/smplock01.scn
index d9189f9..b13bab0 100644
--- a/testsuites/smptests/smplock01/smplock01.scn
+++ b/testsuites/smptests/smplock01/smplock01.scn
@@ -1,22 +1,288 @@
*** BEGIN OF TEST SMPLOCK 1 ***
-aquire global lock with local counter
- processor 0, local counter 15964
- processor 1, local counter 99982377
- global counter 0, sum of local counter 99998341
-aquire global lock with global counter
- processor 0, local counter 166073
- processor 1, local counter 99569103
- global counter 99735176, sum of local counter 99735176
-aquire local lock with local counter
- processor 0, local counter 148133948
- processor 1, local counter 148148108
- global counter 0, sum of local counter 296282056
-aquire local lock with global counter
- processor 0, local counter 55938783
- processor 1, local counter 55951781
- global counter 55951781, sum of local counter 111890564
-aquire global lock with busy section
- processor 0, local counter 10694328
- processor 1, local counter 10694346
- global counter 0, sum of local counter 21388674
+global ticket lock with local counter
+ processor 0, local counter 830091
+ processor 1, local counter 830090
+ processor 2, local counter 830091
+ processor 3, local counter 830091
+ processor 4, local counter 830091
+ processor 5, local counter 830091
+ processor 6, local counter 830091
+ processor 7, local counter 830091
+ processor 8, local counter 830089
+ processor 9, local counter 830088
+ processor 10, local counter 830090
+ processor 11, local counter 830090
+ processor 12, local counter 830090
+ processor 13, local counter 830092
+ processor 14, local counter 830093
+ processor 15, local counter 830092
+ processor 16, local counter 830092
+ processor 17, local counter 830092
+ processor 18, local counter 830089
+ processor 19, local counter 830092
+ processor 20, local counter 830090
+ processor 21, local counter 830090
+ processor 22, local counter 830090
+ processor 23, local counter 830092
+ global counter 0, sum of local counter 19922178
+global MCS lock with local counter
+ processor 0, local counter 1579723
+ processor 1, local counter 1580054
+ processor 2, local counter 1579890
+ processor 3, local counter 1579777
+ processor 4, local counter 1579884
+ processor 5, local counter 1580005
+ processor 6, local counter 1578632
+ processor 7, local counter 1578637
+ processor 8, local counter 1578774
+ processor 9, local counter 1578759
+ processor 10, local counter 1580282
+ processor 11, local counter 1579885
+ processor 12, local counter 1580378
+ processor 13, local counter 1580043
+ processor 14, local counter 1580115
+ processor 15, local counter 1580113
+ processor 16, local counter 1579911
+ processor 17, local counter 1579993
+ processor 18, local counter 1580032
+ processor 19, local counter 1579588
+ processor 20, local counter 1580049
+ processor 21, local counter 1580048
+ processor 22, local counter 1578484
+ processor 23, local counter 1580013
+ global counter 0, sum of local counter 37913069
+global ticket lock with global counter
+ processor 0, local counter 784729
+ processor 1, local counter 784730
+ processor 2, local counter 784730
+ processor 3, local counter 784730
+ processor 4, local counter 784731
+ processor 5, local counter 784730
+ processor 6, local counter 784731
+ processor 7, local counter 784730
+ processor 8, local counter 784731
+ processor 9, local counter 784729
+ processor 10, local counter 784729
+ processor 11, local counter 784730
+ processor 12, local counter 784731
+ processor 13, local counter 784729
+ processor 14, local counter 784728
+ processor 15, local counter 784730
+ processor 16, local counter 784729
+ processor 17, local counter 784730
+ processor 18, local counter 784730
+ processor 19, local counter 784729
+ processor 20, local counter 784729
+ processor 21, local counter 784729
+ processor 22, local counter 784729
+ processor 23, local counter 784731
+ global counter 18833514, sum of local counter 18833514
+global MCS lock with global counter
+ processor 0, local counter 947856
+ processor 1, local counter 947857
+ processor 2, local counter 947857
+ processor 3, local counter 947855
+ processor 4, local counter 947858
+ processor 5, local counter 947857
+ processor 6, local counter 947856
+ processor 7, local counter 947856
+ processor 8, local counter 947856
+ processor 9, local counter 947856
+ processor 10, local counter 947857
+ processor 11, local counter 947856
+ processor 12, local counter 947855
+ processor 13, local counter 947857
+ processor 14, local counter 947857
+ processor 15, local counter 947855
+ processor 16, local counter 947856
+ processor 17, local counter 947855
+ processor 18, local counter 947858
+ processor 19, local counter 947857
+ processor 20, local counter 947858
+ processor 21, local counter 947857
+ processor 22, local counter 947857
+ processor 23, local counter 947857
+ global counter 22748556, sum of local counter 22748556
+local ticket lock with local counter
+ processor 0, local counter 77155869
+ processor 1, local counter 77158831
+ processor 2, local counter 77081105
+ processor 3, local counter 77082737
+ processor 4, local counter 77075777
+ processor 5, local counter 77076154
+ processor 6, local counter 77065268
+ processor 7, local counter 77066500
+ processor 8, local counter 77106686
+ processor 9, local counter 77107321
+ processor 10, local counter 77060207
+ processor 11, local counter 77062079
+ processor 12, local counter 77059638
+ processor 13, local counter 77059931
+ processor 14, local counter 77056750
+ processor 15, local counter 77057813
+ processor 16, local counter 76659137
+ processor 17, local counter 76659205
+ processor 18, local counter 76669140
+ processor 19, local counter 76670415
+ processor 20, local counter 76674221
+ processor 21, local counter 76674630
+ processor 22, local counter 76434805
+ processor 23, local counter 76434361
+ global counter 0, sum of local counter 1846208580
+local MCS lock with local counter
+ processor 0, local counter 44963740
+ processor 1, local counter 45045357
+ processor 2, local counter 45023035
+ processor 3, local counter 45021994
+ processor 4, local counter 44912701
+ processor 5, local counter 44951749
+ processor 6, local counter 45090697
+ processor 7, local counter 45089463
+ processor 8, local counter 45015619
+ processor 9, local counter 45088716
+ processor 10, local counter 45064955
+ processor 11, local counter 45063568
+ processor 12, local counter 44966963
+ processor 13, local counter 45002743
+ processor 14, local counter 45127830
+ processor 15, local counter 45126512
+ processor 16, local counter 44947194
+ processor 17, local counter 44992882
+ processor 18, local counter 45006760
+ processor 19, local counter 45005553
+ processor 20, local counter 44880447
+ processor 21, local counter 44889042
+ processor 22, local counter 45036454
+ processor 23, local counter 45036288
+ global counter 0, sum of local counter 1080350262
+local ticket lock with global counter
+ processor 0, local counter 3962116
+ processor 1, local counter 3963441
+ processor 2, local counter 3963482
+ processor 3, local counter 3963367
+ processor 4, local counter 3962978
+ processor 5, local counter 3963102
+ processor 6, local counter 3962979
+ processor 7, local counter 3962911
+ processor 8, local counter 3962974
+ processor 9, local counter 3963125
+ processor 10, local counter 3963056
+ processor 11, local counter 3963093
+ processor 12, local counter 3962996
+ processor 13, local counter 3963100
+ processor 14, local counter 3963096
+ processor 15, local counter 3963028
+ processor 16, local counter 3967076
+ processor 17, local counter 3967251
+ processor 18, local counter 3967222
+ processor 19, local counter 3967093
+ processor 20, local counter 3972862
+ processor 21, local counter 3972917
+ processor 22, local counter 3967217
+ processor 23, local counter 3967220
+ global counter 7095791, sum of local counter 95157702
+local MCS lock with global counter
+ processor 0, local counter 3849478
+ processor 1, local counter 3860113
+ processor 2, local counter 3966891
+ processor 3, local counter 3966750
+ processor 4, local counter 3973618
+ processor 5, local counter 4014013
+ processor 6, local counter 3914674
+ processor 7, local counter 3914601
+ processor 8, local counter 3910536
+ processor 9, local counter 3924908
+ processor 10, local counter 3995362
+ processor 11, local counter 3995130
+ processor 12, local counter 3909912
+ processor 13, local counter 3923977
+ processor 14, local counter 3995941
+ processor 15, local counter 3995667
+ processor 16, local counter 3842753
+ processor 17, local counter 3852728
+ processor 18, local counter 3956029
+ processor 19, local counter 3955977
+ processor 20, local counter 3961870
+ processor 21, local counter 4001067
+ processor 22, local counter 3911767
+ processor 23, local counter 3911724
+ global counter 8503087, sum of local counter 94505486
+global ticket lock with busy section
+ processor 0, local counter 614377
+ processor 1, local counter 614376
+ processor 2, local counter 614377
+ processor 3, local counter 614377
+ processor 4, local counter 614377
+ processor 5, local counter 614378
+ processor 6, local counter 614377
+ processor 7, local counter 614377
+ processor 8, local counter 614377
+ processor 9, local counter 614376
+ processor 10, local counter 614378
+ processor 11, local counter 614377
+ processor 12, local counter 614377
+ processor 13, local counter 614377
+ processor 14, local counter 614377
+ processor 15, local counter 614376
+ processor 16, local counter 614377
+ processor 17, local counter 614377
+ processor 18, local counter 614377
+ processor 19, local counter 614378
+ processor 20, local counter 614378
+ processor 21, local counter 614377
+ processor 22, local counter 614377
+ processor 23, local counter 614377
+ global counter 0, sum of local counter 14745049
+global MCS lock with busy section
+ processor 0, local counter 552660
+ processor 1, local counter 552661
+ processor 2, local counter 552659
+ processor 3, local counter 552659
+ processor 4, local counter 552660
+ processor 5, local counter 552659
+ processor 6, local counter 552659
+ processor 7, local counter 552660
+ processor 8, local counter 552660
+ processor 9, local counter 552660
+ processor 10, local counter 552660
+ processor 11, local counter 552659
+ processor 12, local counter 552660
+ processor 13, local counter 552659
+ processor 14, local counter 552660
+ processor 15, local counter 552661
+ processor 16, local counter 552660
+ processor 17, local counter 552659
+ processor 18, local counter 552660
+ processor 19, local counter 552661
+ processor 20, local counter 552660
+ processor 21, local counter 552661
+ processor 22, local counter 552660
+ processor 23, local counter 552661
+ global counter 0, sum of local counter 13263838
+sequence lock
+ processor 0, local counter 12138641
+ processor 1, local counter 8
+ processor 2, local counter 64
+ processor 3, local counter 89
+ processor 4, local counter 208
+ processor 5, local counter 227
+ processor 6, local counter 69
+ processor 7, local counter 82
+ processor 8, local counter 2019
+ processor 9, local counter 2017
+ processor 10, local counter 1914
+ processor 11, local counter 2008
+ processor 12, local counter 1890
+ processor 13, local counter 1902
+ processor 14, local counter 1734
+ processor 15, local counter 1701
+ processor 16, local counter 2198
+ processor 17, local counter 2176
+ processor 18, local counter 2011
+ processor 19, local counter 2047
+ processor 20, local counter 2072
+ processor 21, local counter 2084
+ processor 22, local counter 1866
+ processor 23, local counter 1849
+ global counter 0, sum of local counter 12170876
*** END OF TEST SMPLOCK 1 ***
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