Re: [PATCH 1/3] drm/radeon: stop poisoning the GART TLB

["Michel Dänzer" <michel@daenzer.net>]

On 19.06.2014 18:45, Christian König wrote:
> Am 19.06.2014 03:48, schrieb Michel Dänzer:
>> On 15.06.2014 21:48, Christian König wrote:
>>>
>>> No idea what goes wrong when Marek runs piglit, but 3.15.0+"stop
>>> poisoning the GART TLB"+"force_gtt" is rock solid here.
>> FWIW, 3.15 doesn't survive piglit on my Bonaire either, but 3.14 is
>> fine. 3.15 seems stable on Kaveri though, but I haven't tried the
>> force_gtt patch on that yet.
> 
> Yeah, I think it's just me who has a stable system with 3.15 and that
> annoys me quite a bit.

FWIW though, my Kaveri doesn't always survive piglit either, e.g. this
morning it didn't once again, then did after a reboot. (That's using
SDMA; Kaveri was never switched back to CPDMA)


> No idea what's the difference. What versions of LLVM/Mesa/Piglit are you
> using for the test?

Current Git of everything.


>> There have also been a number of bug reports about stability regressions
>> in 3.15 on various SI and CIK cards. It seems likely that at least some
>> of those are related to this issue as well.
>>
>> If we can't figure out the problem soon, we probably need to revert the
>> 'Use normal BOs for page tables' and dependent changes at least for
>> 3.15.y?
> 
> I thought about this for the whole 3.15 release cycle, but decided
> against it. But what we could do is applying the attached trivial patch,
> it pins down the page tables and so pretty much reverts to the old
> behavior.

This patch applied on top of 3.15 + stop poisoning the GART TLB doesn't
seem to help on my Bonaire, unfortunately.


> I think even when we revert to the old code we have a couple of unsolved
> problems with the VM support or in the driver in general where we should
> try to understand the underlying reason for it instead of applying more
> workarounds.

I'm not suggesting applying more workarounds but going back to a known
more stable state. It seems like we've maneuvered ourselves to a rather
uncomfortable position from there, with no clear way to a better place.
But if we basically started from the 3.14 state again, we have a few
known hurdles like mine and Marek's Bonaire etc. which we know any
further improvements will have to pass before they can be considered for
general consumption.


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