v2->v3: - Simplify the code by using numerous mode only without an unfair option. - Use the latest smp_load_acquire()/smp_store_release() barriers. - Move the queue spinlock code to kernel/locking. - Make the use of queue spinlock the default for x86-64 without user configuration. - Additional performance tuning. v1->v2: - Add some more comments to document what the code does. - Add a numerous CPU mode to support >= 16K CPUs - Add a configuration option to allow lock stealing which can further improve performance in many cases. - Enable wakeup of queue head CPU at unlock time for non-numerous CPU mode. This patch set introduces a queue-based spinlock implementation that can replace the default ticket spinlock without increasing the size of the spinlock data structure. As a result, critical kernel data structures that embed spinlock won't increase in size and breaking data alignments. The queue spinlock has slight better performance than the ticket spinlock in uncontended case. Its performance can be much better with moderate to heavy contention. This patch has the potential of improving the performance of all the workloads that have moderate to heavy spinlock contention. The queue spinlock is especially suitable for NUMA machines with at least 2 sockets, though noticeable performance benefit probably won't show up in machines with less than 4 sockets. The purpose of this patch set is not to solve any particular spinlock contention problems. Those need to be solved by refactoring the code to make more efficient use of the lock or finer granularity ones. The main purpose is to make the lock contention problems more tolerable until someone can spend the time and effort to fix them. Waiman Long (2): qspinlock: Introducing a 4-byte queue spinlock implementation qspinlock, x86: Enable x86-64 to use queue spinlock arch/x86/Kconfig | 1 + arch/x86/include/asm/spinlock.h | 2 + arch/x86/include/asm/spinlock_types.h | 4 + include/asm-generic/qspinlock.h | 156 +++++++++++++ kernel/Kconfig.locks | 7 + kernel/locking/Makefile | 1 + kernel/locking/qspinlock.c | 398 +++++++++++++++++++++++++++++++++ 7 files changed, 569 insertions(+), 0 deletions(-) create mode 100644 include/asm-generic/qspinlock.h create mode 100644 kernel/locking/qspinlock.c -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
