On 30/04/2020 18:12, Jakub Jelinek wrote:
> On Thu, Apr 30, 2020 at 05:37:26PM -0300, Adhemerval Zanella via Gcc wrote:
>> Hi all, I would like to check if someone could help me figure out
>> an issue I am chasing on a libgomp patch intended to partially
>> address the issue described at BZ#79784.
>>
>> I have identified that one of the bottlenecks is the global barrier
>> used on both thread pool and team which causes a lof of cache ping-pong
>> in high-core count machines. And it seems not be an aarch64 specific
>> issue as hinted by the bugzilla.
>
> This has been a topic of GSoC last year, but the student didn't deliver it
> in usable form and disappeared.
> See e.g. thread with "Work-stealing task scheduling" in subject from
> last year on gcc-patches and other mails on the topic.
In my understanding what I am working is not exactly related to OMP tasking,
although I see that the global barrier is still an issue on omp task scheduling.
What I am trying to optimize in this specific case is the barrier used
on gomp_thread_pool used on constructs like parallel for and maybe a per-thread
barrier could be extended to other libgomp places.
>
> So if you'd have time and motivation to do it properly, it would be greatly
> appreciated.
>
