[Mesa-dev] [PATCH 0/8] Gallium & RadeonSI optimization for Ryzen CPUs

[Michel Dänzer]

On 2018-09-07 4:31 p.m., Marek Olšák wrote:
> On Fri, Sep 7, 2018, 4:34 AM Michel Dänzer <michel at daenzer.net> wrote:
>> On 2018-09-06 10:56 p.m., Axel Davy wrote:
>>
>>> I fear if we begin to do the work manually, there won't be interest to
>>> do that in the kernel,
>>> and thus all applications will need to include such core pinning code to
>>> have good performance when
>>> multithreaded.
>>
>> I'm also a bit worried that this solution could result in multiple
>> processes contending for the same set of CPU cores, while other cores
>> might be underused, which could result in worse overall system performance.
> 
> Any suggestion how to choose the ccx such that processes end up on a
> different one?

One thing you could do is use a random initial offset. That should at
least avoid e.g. most applications using the same toolkit (which may do
OpenGL calls, even if the application itself doesn't) choosing the same one.


> I don't think the performance can be worse than it is right now.

In the worst case, all processes using OpenGL (or at least their OpenGL
related threads, but that usually includes the main thread) could end up
restricted to the same 4 cores, leaving up to 28 cores underused.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer