Changes in v2:
- Addressed review comments
- Fixed lockless algorithm (must not dec if negative in addition to if 0)
- Made spinlock irqsave (fences are completed in IRQs)
This patch adds code to allocate semaphores in a dynamic way using
a lockless algorithm.
1. Semaphore BOs
Semaphore BOs are
On Mon, Feb 01, 2010 at 10:50:09AM +0100, Luca Barbieri wrote:
> This patch adds code to allocate semaphores in a dynamic way using
> an algorithm with a lockless fast path.
some minor comments below
>
> 1. Semaphore BOs
>
> Semaphore BOs are BOs containing semaphores. Each is 4KB large and
> c
Luca Barbieri writes:
>> Sounds like premature optimization to me. I'm just stating my personal
>> view here, but I have a feeling a patch with 60% of lines could do very
>> well the same for most realistic cases.
>
> Perhaps, but really, the only thing you would probably save by using
> spinlock
> Sounds like premature optimization to me. I'm just stating my personal
> view here, but I have a feeling a patch with 60% of lines could do very
> well the same for most realistic cases.
Perhaps, but really, the only thing you would probably save by using
spinlocks in the fast path is retrying i
Luca Barbieri writes:
>> How often do we expect cross-channel sync to kick in? Maybe 2-3 times
>> per frame? I suspect contentions will be rare enough to make spinlocks
>> as fast as atomics for all real-life cases, and they don't have such a
>> high maintainability cost. What do you guys think?
> How often do we expect cross-channel sync to kick in? Maybe 2-3 times
> per frame? I suspect contentions will be rare enough to make spinlocks
> as fast as atomics for all real-life cases, and they don't have such a
> high maintainability cost. What do you guys think?
For the case of a single (o
Luca Barbieri writes:
> This patch adds code to allocate semaphores in a dynamic way using
> an algorithm with a lockless fast path.
>
> 1. Semaphore BOs
>
> Semaphore BOs are BOs containing semaphores. Each is 4KB large and
> contains 1024 4-byte semaphores. They are pinned.
>
> Semaphore BOs ar
This patch adds code to allocate semaphores in a dynamic way using
an algorithm with a lockless fast path.
1. Semaphore BOs
Semaphore BOs are BOs containing semaphores. Each is 4KB large and
contains 1024 4-byte semaphores. They are pinned.
Semaphore BOs are allocated on-demand and freed at devi
