diff options
| -rw-r--r-- | ChangeLog | 16 | ||||
| -rw-r--r-- | tests/test-lock.c | 79 |
2 files changed, 83 insertions, 12 deletions
@@ -1,3 +1,19 @@ +2016-12-24 Bruno Haible <bruno@clisp.org> + + lock test: Fix performance problem on multi-core machines. + * tests/test-lock.c (USE_VOLATILE): New macro. + (struct atomic_int): New type. + (init_atomic_int, get_atomic_int_value, set_atomic_int_value): New + functions. + (lock_checker_done, rwlock_checker_done, reclock_checker_done): Define + as 'struct atomic_int'. + (lock_checker_thread, test_lock, rwlock_checker_thread, test_rwlock, + reclock_checker_thread, test_recursive_lock): Use the new functions. + Reported by Eric Blake in + https://www.redhat.com/archives/libvir-list/2012-March/msg00854.html + and by Pádraig Brady in + http://lists.gnu.org/archive/html/bug-gnulib/2016-12/msg00117.html. + 2016-12-19 Bruno Haible <bruno@clisp.org> vma-iter: Fix endless loop on 64-bit Windows. diff --git a/tests/test-lock.c b/tests/test-lock.c index cb734b4e69..aa6de27397 100644 --- a/tests/test-lock.c +++ b/tests/test-lock.c @@ -50,6 +50,13 @@ Uncomment this to see if the operating system has a fair scheduler. */ #define EXPLICIT_YIELD 1 +/* Whether to use 'volatile' on some variables that communicate information + between threads. If set to 0, a lock is used to protect these variables. + If set to 1, 'volatile' is used; this is theoretically equivalent but can + lead to much slower execution (e.g. 30x slower total run time on a 40-core + machine. */ +#define USE_VOLATILE 0 + /* Whether to print debugging messages. */ #define ENABLE_DEBUGGING 0 @@ -103,6 +110,51 @@ # define yield() #endif +#if USE_VOLATILE +struct atomic_int { + volatile int value; +}; +static void +init_atomic_int (struct atomic_int *ai) +{ +} +static int +get_atomic_int_value (struct atomic_int *ai) +{ + return ai->value; +} +static void +set_atomic_int_value (struct atomic_int *ai, int new_value) +{ + ai->value = new_value; +} +#else +struct atomic_int { + gl_lock_define (, lock) + int value; +}; +static void +init_atomic_int (struct atomic_int *ai) +{ + gl_lock_init (ai->lock); +} +static int +get_atomic_int_value (struct atomic_int *ai) +{ + gl_lock_lock (ai->lock); + int ret = ai->value; + gl_lock_unlock (ai->lock); + return ret; +} +static void +set_atomic_int_value (struct atomic_int *ai, int new_value) +{ + gl_lock_lock (ai->lock); + ai->value = new_value; + gl_lock_unlock (ai->lock); +} +#endif + #define ACCOUNT_COUNT 4 static int account[ACCOUNT_COUNT]; @@ -170,12 +222,12 @@ lock_mutator_thread (void *arg) return NULL; } -static volatile int lock_checker_done; +static struct atomic_int lock_checker_done; static void * lock_checker_thread (void *arg) { - while (!lock_checker_done) + while (get_atomic_int_value (&lock_checker_done) == 0) { dbgprintf ("Checker %p before check lock\n", gl_thread_self_pointer ()); gl_lock_lock (my_lock); @@ -200,7 +252,8 @@ test_lock (void) /* Initialization. */ for (i = 0; i < ACCOUNT_COUNT; i++) account[i] = 1000; - lock_checker_done = 0; + init_atomic_int (&lock_checker_done); + set_atomic_int_value (&lock_checker_done, 0); /* Spawn the threads. */ checkerthread = gl_thread_create (lock_checker_thread, NULL); @@ -210,7 +263,7 @@ test_lock (void) /* Wait for the threads to terminate. */ for (i = 0; i < THREAD_COUNT; i++) gl_thread_join (threads[i], NULL); - lock_checker_done = 1; + set_atomic_int_value (&lock_checker_done, 1); gl_thread_join (checkerthread, NULL); check_accounts (); } @@ -254,12 +307,12 @@ rwlock_mutator_thread (void *arg) return NULL; } -static volatile int rwlock_checker_done; +static struct atomic_int rwlock_checker_done; static void * rwlock_checker_thread (void *arg) { - while (!rwlock_checker_done) + while (get_atomic_int_value (&rwlock_checker_done) == 0) { dbgprintf ("Checker %p before check rdlock\n", gl_thread_self_pointer ()); gl_rwlock_rdlock (my_rwlock); @@ -284,7 +337,8 @@ test_rwlock (void) /* Initialization. */ for (i = 0; i < ACCOUNT_COUNT; i++) account[i] = 1000; - rwlock_checker_done = 0; + init_atomic_int (&rwlock_checker_done); + set_atomic_int_value (&rwlock_checker_done, 0); /* Spawn the threads. */ for (i = 0; i < THREAD_COUNT; i++) @@ -295,7 +349,7 @@ test_rwlock (void) /* Wait for the threads to terminate. */ for (i = 0; i < THREAD_COUNT; i++) gl_thread_join (threads[i], NULL); - rwlock_checker_done = 1; + set_atomic_int_value (&rwlock_checker_done, 1); for (i = 0; i < THREAD_COUNT; i++) gl_thread_join (checkerthreads[i], NULL); check_accounts (); @@ -356,12 +410,12 @@ reclock_mutator_thread (void *arg) return NULL; } -static volatile int reclock_checker_done; +static struct atomic_int reclock_checker_done; static void * reclock_checker_thread (void *arg) { - while (!reclock_checker_done) + while (get_atomic_int_value (&reclock_checker_done) == 0) { dbgprintf ("Checker %p before check lock\n", gl_thread_self_pointer ()); gl_recursive_lock_lock (my_reclock); @@ -386,7 +440,8 @@ test_recursive_lock (void) /* Initialization. */ for (i = 0; i < ACCOUNT_COUNT; i++) account[i] = 1000; - reclock_checker_done = 0; + init_atomic_int (&reclock_checker_done); + set_atomic_int_value (&reclock_checker_done, 0); /* Spawn the threads. */ checkerthread = gl_thread_create (reclock_checker_thread, NULL); @@ -396,7 +451,7 @@ test_recursive_lock (void) /* Wait for the threads to terminate. */ for (i = 0; i < THREAD_COUNT; i++) gl_thread_join (threads[i], NULL); - reclock_checker_done = 1; + set_atomic_int_value (&reclock_checker_done, 1); gl_thread_join (checkerthread, NULL); check_accounts (); } |