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MDEV-14529 - InnoDB rw-locks: optimize memory barriers

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Remove volatile modifier from waiters: it's not supposed for inter-thread
communication, use appropriate atomic operations instead.

Changed waiters to int32_t, my_atomic friendly type.
This commit is contained in:
Sergey Vojtovich 2017-12-01 13:37:07 +04:00
commit 5b624f00fc
5 changed files with 13 additions and 10 deletions
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7
storage/innobase/sync/sync0arr.cc
View file

@ -588,7 +588,7 @@ sync_array_cell_print(
fprintf(file,
"number of readers " ULINTPF
", waiters flag %u, "
", waiters flag %d, "
"lock_word: %x\n"
"Last time read locked in file %s line %u\n"
"Last time write locked in file %s line %u"
@ -598,7 +598,7 @@ sync_array_cell_print(
#endif
"\n",
rw_lock_get_reader_count(rwlock),
rwlock->waiters,
my_atomic_load32_explicit(&rwlock->waiters, MY_MEMORY_ORDER_RELAXED),
my_atomic_load32_explicit(&rwlock->lock_word, MY_MEMORY_ORDER_RELAXED),
innobase_basename(rwlock->last_s_file_name),
rwlock->last_s_line,
@ -1397,7 +1397,8 @@ sync_arr_fill_sys_semphore_waits_table(
//OK(fields[SYS_SEMAPHORE_WAITS_HOLDER_LINE]->store(rwlock->line, true));
//fields[SYS_SEMAPHORE_WAITS_HOLDER_LINE]->set_notnull();
OK(field_store_ulint(fields[SYS_SEMAPHORE_WAITS_READERS], rw_lock_get_reader_count(rwlock)));
OK(field_store_ulint(fields[SYS_SEMAPHORE_WAITS_WAITERS_FLAG], (longlong)rwlock->waiters));
OK(field_store_ulint(fields[SYS_SEMAPHORE_WAITS_WAITERS_FLAG],
my_atomic_load32_explicit(&rwlock->waiters, MY_MEMORY_ORDER_RELAXED)));
OK(field_store_ulint(fields[SYS_SEMAPHORE_WAITS_LOCK_WORD],
my_atomic_load32_explicit(&rwlock->lock_word, MY_MEMORY_ORDER_RELAXED)));
OK(field_store_string(fields[SYS_SEMAPHORE_WAITS_LAST_READER_FILE], innobase_basename(rwlock->last_s_file_name)));