[Mesa-dev] Time to merge threaded GL dispatch? (aka glthread)

[Matt Turner]

On Thu, Feb 9, 2017 at 3:03 PM, Marek Olšák <maraeo at gmail.com> wrote:
> On Thu, Feb 9, 2017 at 1:52 PM, Ian Romanick <idr at freedesktop.org> wrote:
>> On 02/08/2017 10:26 AM, Nicolai Hähnle wrote:
>>> On 07.02.2017 23:54, Matt Turner wrote:
>>>> On Tue, Feb 7, 2017 at 10:56 AM, Marek Olšák <maraeo at gmail.com> wrote:
>>>>> On Tue, Feb 7, 2017 at 2:57 AM, Kenneth Graunke
>>>>> <kenneth at whitecape.org> wrote:
>>>>>> On Monday, February 6, 2017 8:54:40 PM PST Marek Olšák wrote:
>>>>>>> On Mon, Feb 6, 2017 at 8:20 PM, Ernst Sjöstrand <ernstp at gmail.com>
>>>>>>> wrote:
>>>>>>>> FYI glmark2 segfaults with mesa_glthread=true. Expected that some
>>>>>>>> programs
>>>>>>>> will segfault?
>>>>>>>
>>>>>>> Yes, even segfaults are expected with mesa_glthread=true.
>>>>>>>
>>>>>>> Marek
>>>>>>
>>>>>> Would it make sense to be crash-free or even regression-free on at
>>>>>> least Piglit, before merging?  (Or are we there already?)
>>>>>
>>>>> It's not necessary. glthread is disabled by default. Nobody has tested
>>>>> piglit with glthread. That will follow after it's been merged, or
>>>>> never if it's never merged.
>>>>
>>>> I don't understand why you're so concerned about merging untested
>>>> code. That violates some pretty fundamental development practices of
>>>> the project.
>>>>
>>>> It's exactly unfinished projects like this that cause problems and
>>>> inevitably have to be deleted later (ilo, openvg, d3d1x, etc). I don't
>>>> think it's a burden to develop something out of the master branch
>>>> until it's somewhat useful.
>>>
>>> The code is already somewhat useful. Actually, make that _very_ useful
>>> (big performance improvement) for _some_ cases.
>>>
>>> I suspect most of the people in this discussion haven't really looked at
>>> the code in detail (myself included). We should probably do some of that
>>> before it is merged, since the code isn't just a new driver that is
>>> isolated in its own directory. So I agree with Emil that it makes sense
>>> to let the patches go over the mailing list once.
>>>
>>> However, it's fine to merge this without passing piglit.
>>
>> No, it absolutely is not fine to merge.  We have never allowed such a
>> thing, and I'll be damned if I'll allow this project to start.  Things
>> that land that are known to be broken never actually get fixed.  Then we
>> have to waste time fielding bug reports and Phoronix threads because
>> users turn on the performance features and everything breaks.  It's just
>> a terrible idea.
>
> It does pass piglit, but only when it's disabled.

Have you actually run piglit? What are the results on radeonsi for
glthread=true vs glthread=false?