[Mesa-dev] [PATCH 2/2] r600g: simplify and fix flushing and synchronization v2

[Marek Olšák]

On Mon, Jul 23, 2012 at 4:25 PM, Jerome Glisse <j.glisse at gmail.com> wrote:
> On Sun, Jul 22, 2012 at 8:58 PM, Marek Olšák <maraeo at gmail.com> wrote:
>> On Fri, Jul 20, 2012 at 4:54 AM, Jerome Glisse <j.glisse at gmail.com> wrote:
>>> On Thu, Jul 19, 2012 at 10:25 PM, Marek Olšák <maraeo at gmail.com> wrote:
>>>> On Fri, Jul 20, 2012 at 4:17 AM, Jerome Glisse <j.glisse at gmail.com> wrote:
>>>>> On Thu, Jul 19, 2012 at 10:06 PM, Marek Olšák <maraeo at gmail.com> wrote:
>>>>>> I actually care a lot about lockups. Well, you are complaing about
>>>>>> lockups, yet you have quite obvious bugs in your hyperz code, so let's
>>>>>> fix them first. (I wouldn't even try and run the hyperz code in its
>>>>>> current state. Please don't take that personally.) Then, if the
>>>>>> lockups persist, we can start looking into *what* fixes them. You seem
>>>>>> to think that this patch helps a lot, but you don't say why. Aren't
>>>>>> you interested in what sequence of GPU commands helps? If I am
>>>>>> counting correctly, there are 7 changes in behavior in this patch. It
>>>>>> should be pretty easy to nail down the few that help, document them
>>>>>> (like /* these two lines fix a lockup with hyperz */), and discard the
>>>>>> rest. The documenting part is very important, so that the other
>>>>>> developers won't break your code accidentally.
>>>>>>
>>>>>> Marek
>>>>>>
>>>>>
>>>>> You haven't even try hyperz and you say i have an obvious bug, that's
>>>>> kind of funny, but you would not know why. I try pretty much all of
>>>>
>>>> Oh come on, I already told you about all the bugs I found in the
>>>> hyperz patch. You now know them too, and so does everybody else
>>>> reading mesa-dev.
>>>>
>>>> Marek
>>>>
>>>
>>> None of the issue you pointed out showed in piglit, none of them did
>>> have impact on things like openarena, nexuiz, doomIII, lightmark, ...
>>> so no issue you pointed does not cripple the hyperz patch, it's
>>> working quite well for many things. Before you extrapolate, yes issue
>>> you pointed out have impact in backward use of GL but none the less i
>>> addressed them and i can tell you it does help a bit with lockup.
>>
>> I have no doubt that it helps with your lockups and I also have no
>> doubt that the piece of code that helps can be bisected. I have
>> mentioned 7 changes in the patch which are questionable, so the
>> bisection should ideally take 3 steps. After we find the change which
>> helps (and document it), we can discard the rest. That should give us
>> the same stability as this patch does, but without unnecessary code
>> which does cost GPU cycles (regardless of whether it is measurable on
>> a particular machine or not).
>>
>> By the way, in draw_vbo, the emit functions should be called after
>> r600_need_cs_space. Otherwise the command stream may overflow.
>>
>> Marek
>
> Again i haven't found a combination other than the outcome of the full
> patch that helps more. So be my guest bisect on rv610, rv635, rv670,
> rv710, rv740, rv770.

So your patch doesn't fix any issue with evergreen? That's great.
Thanks for keeping that to yourself. It's always a pleasure working
with you. :) Now that we know the truth, the questionable changes to
the evergreen code can be discarded freely.

Concerning older chipsets, I can do the bisection only on rs880, rv670
and rv730. That will have to suffice. One way or another, every single
change must be done for a *reason* and that reason should be
documented if it's not obvious. Please give me all the necessary
information, so that I can start bisecting. That is what lockups your
patch fixes and where (name apps or tests, a specific place in a game,
etc.) on what chipsets and whether hyperz is enabled.

It is very likely that all the changes I questioned in my first email
do not make any difference with regard to lockups, because there are
also other changes in your patch which may help too and which I fully
agree with.

Marek