CIK hangs with kernel 3.15, bisected

Tue May 13 09:08:18 PDT 2014

I think it's caused by something else. I'll continue testing and bisecting.

Marek

On Tue, May 13, 2014 at 5:31 PM, Christian König
<deathsimple at vodafone.de> wrote:
> Is the performance regression regression caused by the page table changes or
> something else?
>
> I did made some tests with xonotic while developing it and it didn't showed
> anything obvious, but I didn't made tests on different systems.
>
> Christian.
>
> Am 13.05.2014 17:19, schrieb Marek Olšák:
>
>> Your latest patches fix the regression.
>>
>> The performance regression can also be reproduced with piglit "-t
>> texelFetch.fs".
>>
>> Kernel 3.14:
>>     real    0m17.724s
>>     user    0m41.905s
>>     sys    0m11.299s
>>
>> The problematic commit checked out + your fixes (without the PTE patch I
>> think):
>>     real    0m23.474s
>>     user    1m1.008s
>>     sys    0m13.812s
>>
>> Marek
>>
>>
>> On Tue, May 13, 2014 at 3:57 PM, Christian König
>> <deathsimple at vodafone.de> wrote:
>>>
>>> Am 13.05.2014 15:22, schrieb Alex Deucher:
>>>
>>>> On Mon, May 12, 2014 at 7:38 PM, Grigori Goronzy <greg at chown.ath.cx>
>>>> wrote:
>>>>>
>>>>> I can confirm this fixes it for me, too.
>>>>>
>>>>> 3.15 with these fixes and the large PTE patches actually ends up being
>>>>> noticeably slower than earlier kernels with Xonotic, though. I wonder
>>>>> what's
>>>>> going on.
>>>>
>>>> Allocation overhead?
>>>
>>>
>>> Unlikely, Xonotic just allocates a single page table at start, which then
>>> gets extended to a certain rate until they no longer need more address
>>> space
>>> and are done with it.
>>>
>>> Grigori, can you bisect and/or try to figure out what's wrong here?
>>>
>>> Christian.
>>>
>>>
>>>>
>>>>> Grigori
>>>>>
>>>>>
>>>>> On 12.05.2014 14:50, Christian König wrote:
>>>>>>
>>>>>> I could reproduce the problem with xonotic and I think I've found the
>>>>>> issue.
>>>>>>
>>>>>> Please test the attached patch.
>>>>>>
>>>>>> Thanks,
>>>>>> Christian.
>>>>>>
>>>>>> Am 11.05.2014 11:06, schrieb Christian König:
>>>>>>>>
>>>>>>>> I have tested it and it doesn't fix the hangs.
>>>>>>>
>>>>>>> Yeah, thought so. Well it was just a guess.
>>>>>>>
>>>>>>>> (Also, I don't like the patch, because it reverts the behavior I
>>>>>>>> added
>>>>>>>> for userspace buffers.)
>>>>>>>
>>>>>>> Actually it shouldn't affect that. The alternative domain always
>>>>>>> contains GART even when userspace only specified VRAM as placement
>>>>>>> (as
>>>>>>> long as it is technical possible to do so).
>>>>>>>
>>>>>>> So what should happen is that TTM sees the current placement, matches
>>>>>>> that with the desired placement and should find that it doesn't need
>>>>>>> to move the buffer (we should just test if this behavior really works
>>>>>>> as expected).
>>>>>>>
>>>>>>> Christian.
>>>>>>>
>>>>>>> Am 10.05.2014 23:38, schrieb Marek Olšák:
>>>>>>>>
>>>>>>>> Hi Christian,
>>>>>>>>
>>>>>>>> I have tested it and it doesn't fix the hangs.
>>>>>>>>
>>>>>>>> (Also, I don't like the patch, because it reverts the behavior I
>>>>>>>> added
>>>>>>>> for userspace buffers.)
>>>>>>>>
>>>>>>>> Marek
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Sat, May 10, 2014 at 6:34 PM, Christian König
>>>>>>>> <deathsimple at vodafone.de> wrote:
>>>>>>>>>
>>>>>>>>> Couldn't reproduce the issue so far. So the attached patch is just
>>>>>>>>> a
>>>>>>>>> complete shoot into the dark found by rereading the code, but it
>>>>>>>>> might
>>>>>>>>> actually be the problem.
>>>>>>>>>
>>>>>>>>> Please give it a try.
>>>>>>>>>
>>>>>>>>> Going to keep testing in the meantime,
>>>>>>>>> Christian.
>>>>>>>>>
>>>>>>>>> Am 10.05.2014 10:23, schrieb Christian König:
>>>>>>>>>
>>>>>>>>>>> I see hangs with kernel 3.15 and SI under memory pressure, e.g.
>>>>>>>>>>> if
>>>>>>>>>>> I boot
>>>>>>>>>>> with radeon.vramlimit=256 and then run Xonotic timedemo with high
>>>>>>>>>>> settings.
>>>>>>>>>>> I haven't had a chance to bisect it yet, but it might be a
>>>>>>>>>>> similar
>>>>>>>>>>> problem.
>>>>>>>>>>
>>>>>>>>>> Sounds like the same issue to me. Thx for the good test case.
>>>>>>>>>>
>>>>>>>>>>> Any idea what is wrong with it?
>>>>>>>>>>
>>>>>>>>>> Actually I already wondered that it went so smooth without any
>>>>>>>>>> regression
>>>>>>>>>> so far, didn't noticed the bug in bugzilla.kernel.org yet.
>>>>>>>>>>
>>>>>>>>>>> Some of the tests allocate a lot of MSAA textures and the tests
>>>>>>>>>>> also
>>>>>>>>>>> run in parallel, which creates a lot of memory pressure and
>>>>>>>>>>> probably
>>>>>>>>>>> causes buffer evictions.
>>>>>>>>>>
>>>>>>>>>> Sounds like the underlying problem to me. We probably evict some
>>>>>>>>>> part of a
>>>>>>>>>> page table without updating the page directory. Going to dig into
>>>>>>>>>> it today,
>>>>>>>>>> it's probably just a one liner missing somewhere in the VM code.
>>>>>>>>>>
>>>>>>>>>> Christian.
>>>>>>>>>>
>>>>>>>>>> Am 09.05.2014 23:39, schrieb Grigori Goronzy:
>>>>>>>>>>>
>>>>>>>>>>> On 09.05.2014 20:03, Marek Olšák wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> This commit which first appeared in 3.15-rc1 causes hangs on
>>>>>>>>>>>> Bonaire:
>>>>>>>>>>>> [...]
>>>>>>>>>>>>
>>>>>>>>>>>> The simplest way to reproduce the hangs is to run piglit with
>>>>>>>>>>>> these
>>>>>>>>>>>> parameters:
>>>>>>>>>>>> -t texelFetch.fs
>>>>>>>>>>>>
>>>>>>>>>>>> Some of the tests allocate a lot of MSAA textures and the tests
>>>>>>>>>>>> also
>>>>>>>>>>>> run in parallel, which creates a lot of memory pressure and
>>>>>>>>>>>> probably
>>>>>>>>>>>> causes buffer evictions.
>>>>>>>>>>>>
>>>>>>>>>>> I see hangs with kernel 3.15 and SI under memory pressure, e.g.
>>>>>>>>>>> if
>>>>>>>>>>> I boot
>>>>>>>>>>> with radeon.vramlimit=256 and then run Xonotic timedemo with high
>>>>>>>>>>> settings.
>>>>>>>>>>> I haven't had a chance to bisect it yet, but it might be a
>>>>>>>>>>> similar
>>>>>>>>>>> problem.
>>>>>>>>>>>
>>>>>>>>>>> Grigori
>>>>>>>>>>
>>>>>>>>>>
>>>>> _______________________________________________
>>>>> dri-devel mailing list
>>>>> dri-devel at lists.freedesktop.org
>>>>> http://lists.freedesktop.org/mailman/listinfo/dri-devel
>>>
>>>
>