On 02/18/2014 02:31 AM, Peter Zijlstra wrote:
On Mon, Feb 17, 2014 at 02:47:03PM -0800, H. Peter Anvin wrote:
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.
It very much needs paravirt muck before we can even consider it.
I will start looking at how to make it work with paravirt. Hopefully, it
won't take too long.
-Longman
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