DIRS=tests
-all: checkarch liburcu.so urcu.o urcu-yield.o urcu-qsbr.o urcu-mb.o subdirs
+all: checkarch liburcu.so urcu.o \
+ liburcu-qsbr.so urcu-qsbr.o \
+ liburcu-mb.so urcu-mb.o \
+ urcu-yield.o \
+ subdirs
checkarch:
ifeq (${ARCHTYPE},)
liburcu.so: urcu.o
$(CC) -fPIC -shared -o $@ $<
+liburcu-qsbr.so: urcu-qsbr.o
+ $(CC) -fPIC -shared -o $@ $<
+
+liburcu-mb.so: urcu-mb.o
+ $(CC) -fPIC -shared -o $@ $<
+
urcu-yield.o: urcu.c urcu.h
$(CC) -DDEBUG_YIELD ${CFLAGS} $(LDFLAGS) -c -o $@ $(SRC_DEP)
-for d in ${DIRS}; do cd $${d}; ${MAKE} ${MFLAGS}; done
install: liburcu.so
- cp -f liburcu.so /usr/lib/
- cp -f arch.h arch_atomic.h compiler.h urcu.h urcu-static.h /usr/include/
+ cp -f liburcu.so liburcu-mb.so liburcu-qsbr.so /usr/lib/
+ cp -f arch.h arch_atomic.h compiler.h \
+ urcu.h urcu-static.h \
+ urcu-qsbr.h urcu-qsbr-static.h \
+ /usr/include/
clean:
rm -f *.o *.so arch.h arch_atomic.h
-Userspace RCU Implementatation
+Userspace RCU Implementation
by Mathieu Desnoyers and Paul E. McKenney
BUILDING
Being careful with signals
- The library uses signals internally. The signal handler is
+ The urcu library uses signals internally. The signal handler is
registered with the SA_RESTART flag. However, these signals may cause
some non-restartable system calls to fail with errno = EINTR. Care
should be taken to restart system calls manually if they fail with this
error. A list of non-restartable system calls may be found in
signal(7). To ensure the Userspace RCU library does not use signals,
- define CONFIG_URCU_AVOID_SIGNALS at compile-time.
+ see "Usage of liburcu-mb" below.
- Read-side critical sections can sit in a signal handler. Be careful,
- however, to disable these signals between thread creation and calls to
- rcu_register_thread(), because a signal handler nesting on an
- unregistered thread would not be allowed to call rcu_read_lock().
+ Read-side critical sections can are allowed in a signal handler with
+ liburcu and liburcu-mb. Be careful, however, to disable these signals
+ between thread creation and calls to rcu_register_thread(), because a
+ signal handler nesting on an unregistered thread would not be allowed to
+ call rcu_read_lock().
-Usage of CONFIG_URCU_AVOID_SIGNALS
+Usage of liburcu
- CONFIG_URCU_AVOID_SIGNALS uses full SMP barriers for readers. This
- eliminates the need for signals but results in slower reads.
+ This is the preferred version of the library, both in terms of speed and
+ flexibility. Define _LGPL_SOURCE if your code is LGPL or GPL (otherwise
+ function calls will be generated instead of inlines). Use the urcu.h
+ header. Link the application with "-lurcu".
+
+Usage of liburcu-mb
+
+ Compile code with "-DCONFIG_URCU_AVOID_SIGNALS" and link with
+ "-lurcu-mb" to use a version of the urcu library which does not need to
+ reserve a signal number. CONFIG_URCU_AVOID_SIGNALS uses full SMP
+ barriers for readers. This eliminates the need for signals but results
+ in slower reads.
+
+Usage of liburcu-qsbr
+
+ The QSBR flavor of RCU needs to have each reader thread executing
+ rcu_quiescent_state() periodically to progress. rcu_thread_online() and
+ rcu_thread_offline() can be used to mark long periods for which the
+ threads are not active. Link with "-lurcu-qsbr" and use urcu-qsbr.h.
Usage of DEBUG_RCU
DEBUG_YIELD is used to add random delays in the code for testing
purposes.
+
+
urcu-asm.S test_qsbr_timing test_qsbr urcu-asm.o urcutorture \
urcutorture-yield test_mutex test_looplen test_urcu_gc \
test_urcu_gc_mb test_qsbr_gc test_qsbr_lgc test_urcu_lgc \
- test_urcu_lgc_mb
+ test_urcu_lgc_mb test_qsbr_dynamic_link
api.h: ${APIHEADER}
cp -f ${APIHEADER} api.h
test_qsbr_lgc: test_qsbr_gc.c ${URCU_QSBR}
$(CC) -DTEST_LOCAL_GC ${CFLAGS} $(LDFLAGS) -o $@ $(SRC_DEP)
+test_qsbr_dynamic_link: test_qsbr.c ${URCU_QSBR}
+ $(CC) ${CFLAGS} -DDYNAMIC_LINK_TEST $(LDFLAGS) -o $@ $(SRC_DEP)
+
test_rwlock: test_rwlock.c ${URCU_SIGNAL}
$(CC) ${CFLAGS} $(LDFLAGS) -o $@ $(SRC_DEP)
}
#endif
+#ifndef DYNAMIC_LINK_TEST
#define _LGPL_SOURCE
+#else
+#define debug_yield_read()
+#endif
#include "../urcu-qsbr.h"
struct test_array {
smp_mb();
for (;;) {
- _rcu_read_lock();
- local_ptr = _rcu_dereference(test_rcu_pointer);
+ rcu_read_lock();
+ local_ptr = rcu_dereference(test_rcu_pointer);
debug_yield_read();
if (local_ptr)
assert(local_ptr->a == 8);
if (unlikely(rduration))
loop_sleep(rduration);
- _rcu_read_unlock();
+ rcu_read_unlock();
nr_reads++;
/* QS each 1024 reads */
if (unlikely((nr_reads & ((1 << 10) - 1)) == 0))
- _rcu_quiescent_state();
+ rcu_quiescent_state();
if (unlikely(!test_duration_read()))
break;
}
for (;;) {
new = test_array_alloc();
new->a = 8;
- old = _rcu_publish_content(&test_rcu_pointer, new);
+ old = rcu_publish_content(&test_rcu_pointer, new);
/* can be done after unlock */
if (old)
old->a = 0;
--- /dev/null
+#ifndef _URCU_QSBR_STATIC_H
+#define _URCU_QSBR_STATIC_H
+
+/*
+ * urcu-qsbr-static.h
+ *
+ * Userspace RCU QSBR header.
+ *
+ * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu-qsbr.h for linking
+ * dynamically with the userspace rcu QSBR library.
+ *
+ * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
+ *
+ * This 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 2.1 of the License, or (at your option) any later version.
+ *
+ * This 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 library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * IBM's contributions to this file may be relicensed under LGPLv2 or later.
+ */
+
+#include <stdlib.h>
+#include <pthread.h>
+#include <assert.h>
+
+#include <compiler.h>
+#include <arch.h>
+
+/*
+ * Identify a shared load. A smp_rmc() or smp_mc() should come before the load.
+ */
+#define _LOAD_SHARED(p) ACCESS_ONCE(p)
+
+/*
+ * Load a data from shared memory, doing a cache flush if required.
+ */
+#define LOAD_SHARED(p) \
+ ({ \
+ smp_rmc(); \
+ _LOAD_SHARED(p); \
+ })
+
+/*
+ * Identify a shared store. A smp_wmc() or smp_mc() should follow the store.
+ */
+#define _STORE_SHARED(x, v) ({ ACCESS_ONCE(x) = (v); })
+
+/*
+ * Store v into x, where x is located in shared memory. Performs the required
+ * cache flush after writing. Returns v.
+ */
+#define STORE_SHARED(x, v) \
+ ({ \
+ _STORE_SHARED(x, v); \
+ smp_wmc(); \
+ (v); \
+ })
+
+/**
+ * _rcu_dereference - reads (copy) a RCU-protected pointer to a local variable
+ * into a RCU read-side critical section. The pointer can later be safely
+ * dereferenced within the critical section.
+ *
+ * This ensures that the pointer copy is invariant thorough the whole critical
+ * section.
+ *
+ * Inserts memory barriers on architectures that require them (currently only
+ * Alpha) and documents which pointers are protected by RCU.
+ *
+ * Should match rcu_assign_pointer() or rcu_xchg_pointer().
+ */
+
+#define _rcu_dereference(p) ({ \
+ typeof(p) _________p1 = LOAD_SHARED(p); \
+ smp_read_barrier_depends(); \
+ (_________p1); \
+ })
+
+/*
+ * This code section can only be included in LGPL 2.1 compatible source code.
+ * See below for the function call wrappers which can be used in code meant to
+ * be only linked with the Userspace RCU library. This comes with a small
+ * performance degradation on the read-side due to the added function calls.
+ * This is required to permit relinking with newer versions of the library.
+ */
+
+/*
+ * If a reader is really non-cooperative and refuses to commit its
+ * rcu_reader_qs_gp count to memory (there is no barrier in the reader
+ * per-se), kick it after a few loops waiting for it.
+ */
+#define KICK_READER_LOOPS 10000
+
+#ifdef DEBUG_RCU
+#define rcu_assert(args...) assert(args)
+#else
+#define rcu_assert(args...)
+#endif
+
+#ifdef DEBUG_YIELD
+#include <sched.h>
+#include <time.h>
+#include <pthread.h>
+#include <unistd.h>
+
+#define YIELD_READ (1 << 0)
+#define YIELD_WRITE (1 << 1)
+
+/* maximum sleep delay, in us */
+#define MAX_SLEEP 50
+
+extern unsigned int yield_active;
+extern unsigned int __thread rand_yield;
+
+static inline void debug_yield_read(void)
+{
+ if (yield_active & YIELD_READ)
+ if (rand_r(&rand_yield) & 0x1)
+ usleep(rand_r(&rand_yield) % MAX_SLEEP);
+}
+
+static inline void debug_yield_write(void)
+{
+ if (yield_active & YIELD_WRITE)
+ if (rand_r(&rand_yield) & 0x1)
+ usleep(rand_r(&rand_yield) % MAX_SLEEP);
+}
+
+static inline void debug_yield_init(void)
+{
+ rand_yield = time(NULL) ^ pthread_self();
+}
+#else
+static inline void debug_yield_read(void)
+{
+}
+
+static inline void debug_yield_write(void)
+{
+}
+
+static inline void debug_yield_init(void)
+{
+
+}
+#endif
+
+static inline void reader_barrier()
+{
+ smp_mb();
+}
+
+/*
+ * Global quiescent period counter with low-order bits unused.
+ * Using a int rather than a char to eliminate false register dependencies
+ * causing stalls on some architectures.
+ */
+extern long urcu_gp_ctr;
+
+extern long __thread rcu_reader_qs_gp;
+
+static inline int rcu_gp_ongoing(long *value)
+{
+ if (value == NULL)
+ return 0;
+
+ return LOAD_SHARED(*value) & 1;
+}
+
+static inline void _rcu_read_lock(void)
+{
+ rcu_assert(rcu_reader_qs_gp & 1);
+}
+
+static inline void _rcu_read_unlock(void)
+{
+}
+
+static inline void _rcu_quiescent_state(void)
+{
+ smp_mb();
+ rcu_reader_qs_gp = ACCESS_ONCE(urcu_gp_ctr) + 1;
+ smp_mb();
+}
+
+static inline void _rcu_thread_offline(void)
+{
+ smp_mb();
+ rcu_reader_qs_gp = ACCESS_ONCE(urcu_gp_ctr);
+}
+
+static inline void _rcu_thread_online(void)
+{
+ rcu_reader_qs_gp = ACCESS_ONCE(urcu_gp_ctr) + 1;
+ smp_mb();
+}
+
+/**
+ * _rcu_assign_pointer - assign (publicize) a pointer to a new data structure
+ * meant to be read by RCU read-side critical sections. Returns the assigned
+ * value.
+ *
+ * Documents which pointers will be dereferenced by RCU read-side critical
+ * sections and adds the required memory barriers on architectures requiring
+ * them. It also makes sure the compiler does not reorder code initializing the
+ * data structure before its publication.
+ *
+ * Should match rcu_dereference_pointer().
+ */
+
+#define _rcu_assign_pointer(p, v) \
+ ({ \
+ if (!__builtin_constant_p(v) || \
+ ((v) != NULL)) \
+ wmb(); \
+ STORE_SHARED(p, v); \
+ })
+
+/**
+ * _rcu_xchg_pointer - same as rcu_assign_pointer, but returns the previous
+ * pointer to the data structure, which can be safely freed after waiting for a
+ * quiescent state using synchronize_rcu().
+ */
+
+#define _rcu_xchg_pointer(p, v) \
+ ({ \
+ if (!__builtin_constant_p(v) || \
+ ((v) != NULL)) \
+ wmb(); \
+ xchg(p, v); \
+ })
+
+/*
+ * Exchanges the pointer and waits for quiescent state.
+ * The pointer returned can be freed.
+ */
+#define _rcu_publish_content(p, v) \
+ ({ \
+ void *oldptr; \
+ oldptr = _rcu_xchg_pointer(p, v); \
+ synchronize_rcu(); \
+ oldptr; \
+ })
+
+#endif /* _URCU_QSBR_STATIC_H */
/*
- * urcu.c
+ * urcu-qsbr.c
*
- * Userspace RCU library
+ * Userspace RCU QSBR library
*
* Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
* Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
#include <errno.h>
#include <poll.h>
-#include "urcu-qsbr.h"
+#include "urcu-qsbr-static.h"
/* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
-//#include "urcu.h"
+#include "urcu-qsbr.h"
pthread_mutex_t urcu_mutex = PTHREAD_MUTEX_INITIALIZER;
return oldptr;
}
+void rcu_quiescent_state(void)
+{
+ _rcu_quiescent_state();
+}
+
+void rcu_thread_offline(void)
+{
+ _rcu_thread_offline();
+}
+
+void rcu_thread_online(void)
+{
+ _rcu_thread_online();
+}
+
static void rcu_add_reader(pthread_t id)
{
struct reader_registry *oldarray;
#define _URCU_QSBR_H
/*
- * urcu-static.h
+ * urcu-qsbr.h
*
- * Userspace RCU header.
+ * Userspace RCU QSBR header.
*
- * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu.h for linking
- * dynamically with the userspace rcu library.
+ * LGPL-compatible code should include this header with :
*
- * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
- * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
+ * #define _LGPL_SOURCE
+ * #include <urcu.h>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
#include <stdlib.h>
#include <pthread.h>
-#include <assert.h>
-
-#include <compiler.h>
-#include <arch.h>
-
-/*
- * Identify a shared load. A smp_rmc() or smp_mc() should come before the load.
- */
-#define _LOAD_SHARED(p) ACCESS_ONCE(p)
-
-/*
- * Load a data from shared memory, doing a cache flush if required.
- */
-#define LOAD_SHARED(p) \
- ({ \
- smp_rmc(); \
- _LOAD_SHARED(p); \
- })
-
-/*
- * Identify a shared store. A smp_wmc() or smp_mc() should follow the store.
- */
-#define _STORE_SHARED(x, v) ({ ACCESS_ONCE(x) = (v); })
/*
- * Store v into x, where x is located in shared memory. Performs the required
- * cache flush after writing. Returns v.
- */
-#define STORE_SHARED(x, v) \
- ({ \
- _STORE_SHARED(x, v); \
- smp_wmc(); \
- (v); \
- })
-
-/**
- * _rcu_dereference - reads (copy) a RCU-protected pointer to a local variable
- * into a RCU read-side critical section. The pointer can later be safely
- * dereferenced within the critical section.
- *
- * This ensures that the pointer copy is invariant thorough the whole critical
- * section.
+ * Important !
*
- * Inserts memory barriers on architectures that require them (currently only
- * Alpha) and documents which pointers are protected by RCU.
- *
- * Should match rcu_assign_pointer() or rcu_xchg_pointer().
+ * Each thread containing read-side critical sections must be registered
+ * with rcu_register_thread() before calling rcu_read_lock().
+ * rcu_unregister_thread() should be called before the thread exits.
*/
-#define _rcu_dereference(p) ({ \
- typeof(p) _________p1 = LOAD_SHARED(p); \
- smp_read_barrier_depends(); \
- (_________p1); \
- })
-
-/*
- * This code section can only be included in LGPL 2.1 compatible source code.
- * See below for the function call wrappers which can be used in code meant to
- * be only linked with the Userspace RCU library. This comes with a small
- * performance degradation on the read-side due to the added function calls.
- * This is required to permit relinking with newer versions of the library.
- */
+#ifdef _LGPL_SOURCE
-/*
- * The signal number used by the RCU library can be overridden with
- * -DSIGURCU= when compiling the library.
- */
-#ifndef SIGURCU
-#define SIGURCU SIGUSR1
-#endif
+#include <urcu-qsbr-static.h>
/*
- * If a reader is really non-cooperative and refuses to commit its
- * rcu_reader_qs_gp count to memory (there is no barrier in the reader
- * per-se), kick it after a few loops waiting for it.
+ * Mappings for static use of the userspace RCU library.
+ * Should only be used in LGPL-compatible code.
*/
-#define KICK_READER_LOOPS 10000
-#ifdef DEBUG_RCU
-#define rcu_assert(args...) assert(args)
-#else
-#define rcu_assert(args...)
-#endif
+#define rcu_dereference _rcu_dereference
+#define rcu_read_lock _rcu_read_lock
+#define rcu_read_unlock _rcu_read_unlock
-#ifdef DEBUG_YIELD
-#include <sched.h>
-#include <time.h>
-#include <pthread.h>
-#include <unistd.h>
+#define rcu_quiescent_state _rcu_quiescent_state
+#define rcu_thread_offline _rcu_thread_offline
+#define rcu_thread_online _rcu_thread_online
-#define YIELD_READ (1 << 0)
-#define YIELD_WRITE (1 << 1)
+#define rcu_assign_pointer _rcu_assign_pointer
+#define rcu_xchg_pointer _rcu_xchg_pointer
+#define rcu_publish_content _rcu_publish_content
-/* maximum sleep delay, in us */
-#define MAX_SLEEP 50
-
-extern unsigned int yield_active;
-extern unsigned int __thread rand_yield;
-
-static inline void debug_yield_read(void)
-{
- if (yield_active & YIELD_READ)
- if (rand_r(&rand_yield) & 0x1)
- usleep(rand_r(&rand_yield) % MAX_SLEEP);
-}
-
-static inline void debug_yield_write(void)
-{
- if (yield_active & YIELD_WRITE)
- if (rand_r(&rand_yield) & 0x1)
- usleep(rand_r(&rand_yield) % MAX_SLEEP);
-}
-
-static inline void debug_yield_init(void)
-{
- rand_yield = time(NULL) ^ pthread_self();
-}
-#else
-static inline void debug_yield_read(void)
-{
-}
-
-static inline void debug_yield_write(void)
-{
-}
-
-static inline void debug_yield_init(void)
-{
-
-}
-#endif
-
-static inline void reader_barrier()
-{
- smp_mb();
-}
+#else /* !_LGPL_SOURCE */
/*
- * Global quiescent period counter with low-order bits unused.
- * Using a int rather than a char to eliminate false register dependencies
- * causing stalls on some architectures.
+ * library wrappers to be used by non-LGPL compatible source code.
*/
-extern long urcu_gp_ctr;
-extern long __thread rcu_reader_qs_gp;
+extern void rcu_read_lock(void);
+extern void rcu_read_unlock(void);
-static inline int rcu_gp_ongoing(long *value)
-{
- if (value == NULL)
- return 0;
+extern void *rcu_dereference(void *p);
- return LOAD_SHARED(*value) & 1;
-}
+extern void rcu_quiescent_state(void);
+extern void rcu_thread_offline(void);
+extern void rcu_thread_online(void);
-static inline void _rcu_read_lock(void)
-{
- rcu_assert(rcu_reader_qs_gp & 1);
-}
+extern void *rcu_assign_pointer_sym(void **p, void *v);
-static inline void _rcu_read_unlock(void)
-{
-}
+#define rcu_assign_pointer(p, v) \
+ rcu_assign_pointer_sym((void **)(p), (v))
-static inline void _rcu_quiescent_state(void)
-{
- smp_mb();
- rcu_reader_qs_gp = ACCESS_ONCE(urcu_gp_ctr) + 1;
- smp_mb();
-}
+extern void *rcu_xchg_pointer_sym(void **p, void *v);
+#define rcu_xchg_pointer(p, v) \
+ rcu_xchg_pointer_sym((void **)(p), (v))
-static inline void _rcu_thread_offline(void)
-{
- smp_mb();
- rcu_reader_qs_gp = ACCESS_ONCE(urcu_gp_ctr);
-}
+extern void *rcu_publish_content_sym(void **p, void *v);
+#define rcu_publish_content(p, v) \
+ rcu_publish_content_sym((void **)(p), (v))
-static inline void _rcu_thread_online(void)
-{
- rcu_reader_qs_gp = ACCESS_ONCE(urcu_gp_ctr) + 1;
- smp_mb();
-}
-
-/**
- * _rcu_assign_pointer - assign (publicize) a pointer to a new data structure
- * meant to be read by RCU read-side critical sections. Returns the assigned
- * value.
- *
- * Documents which pointers will be dereferenced by RCU read-side critical
- * sections and adds the required memory barriers on architectures requiring
- * them. It also makes sure the compiler does not reorder code initializing the
- * data structure before its publication.
- *
- * Should match rcu_dereference_pointer().
- */
-
-#define _rcu_assign_pointer(p, v) \
- ({ \
- if (!__builtin_constant_p(v) || \
- ((v) != NULL)) \
- wmb(); \
- STORE_SHARED(p, v); \
- })
-
-/**
- * _rcu_xchg_pointer - same as rcu_assign_pointer, but returns the previous
- * pointer to the data structure, which can be safely freed after waiting for a
- * quiescent state using synchronize_rcu().
- */
-
-#define _rcu_xchg_pointer(p, v) \
- ({ \
- if (!__builtin_constant_p(v) || \
- ((v) != NULL)) \
- wmb(); \
- xchg(p, v); \
- })
-
-/*
- * Exchanges the pointer and waits for quiescent state.
- * The pointer returned can be freed.
- */
-#define _rcu_publish_content(p, v) \
- ({ \
- void *oldptr; \
- oldptr = _rcu_xchg_pointer(p, v); \
- synchronize_rcu(); \
- oldptr; \
- })
+#endif /* !_LGPL_SOURCE */
extern void synchronize_rcu(void);
*/
#define KICK_READER_LOOPS 10000
+#ifdef DEBUG_RCU
+#define rcu_assert(args...) assert(args)
+#else
+#define rcu_assert(args...)
+#endif
+
#ifdef DEBUG_YIELD
#include <sched.h>
#include <time.h>
projects / urcu.git / commitdiff
