On 02/17/2014 12:41 PM, Waiman Long wrote:
> v3->v4:
> - Remove debugging code and fix a configuration error
> - Simplify the qspinlock structure and streamline the code to make it
> perform a bit better
> - Add an x86 version of asm/qspinlock.h for holding x86 specific
> optimization.
> - Add an optimized x86 code path for 2 contending tasks to improve
> low contention performance.
>
> 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.
>
This is starting to look good, so I have pulled it into
tip:x86/spinlocks to start give it some testing mileage.
-hpa
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