linux-kernel - Re: Kernel and ADM hardware roulette ( was AMD graphics performance regression in 4.15 and later )

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Date:   Wed, 6 Jun 2018 17:24:21 +0200
From:   Gabriel C <nix.or.die@...il.com>
To:     Christian König <christian.koenig@....com>
Cc:     Michel Dänzer <michel.daenzer@....com>,
        Jean-Marc Valin <jmvalin@...illa.com>,
        Dave Airlie <airlied@...ux.ie>, alexander.deucher@....com,
        Felix Kuehling <Felix.Kuehling@....com>,
        Laura Abbott <labbott@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        dri-devel@...ts.freedesktop.org,
        LKML <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: Kernel and ADM hardware roulette ( was AMD graphics performance
 regression in 4.15 and later )

2018-06-06 16:44 GMT+02:00 Christian König <christian.koenig@....com>:
> Am 06.06.2018 um 16:12 schrieb Michel Dänzer:
>>
>> On 2018-06-06 03:33 PM, Gabriel C wrote:
>>>
>>> 2018-06-06 14:19 GMT+02:00 Christian König <christian.koenig@....com>:
>>>>
>>>> Am 06.06.2018 um 14:08 schrieb Gabriel C:
>>>>>
>>>>> 2018-06-06 13:33 GMT+02:00 Christian König <christian.koenig@....com>:
>>>>>>
>>>>>> Am 06.06.2018 um 13:28 schrieb Gabriel C:
>>>>>>>
>>>>>>> 2018-04-11 7:02 GMT+02:00 Gabriel C <nix.or.die@...il.com>:
>>>>>>>>
>>>>>>>>
>>>>>>>> [    6.337838] [drm] PCIE GART of 2048M enabled (table at
>>>>>>>> 0x00000000001D6000).
>>>>>>>> [    6.338210] radeon 0000:21:00.0: (-12) create WB bo failed
>>>>>>>> [    6.338214] radeon 0000:21:00.0: disabling GPU acceleration
>>>>>>>>
>>>>>>>> ...
>>>>>>>>
>>>>>>> I have the same Issue now on final 4.17.
>>
>>
>> Please file a bug report, and ideally bisect which commit(s) introduced
>> the issue(s).
>>
>>
>>>>>
>>>>> http://ftp.frugalware.org/pub/other/people/crazy/radeon/dmesg-iommu-sr-iov-off.txt
>>>>>
>>>>>
>>>>> http://ftp.frugalware.org/pub/other/people/crazy/radeon/dmesg-iommu-sr-iov-on.txt
>>>>>
>>>>> Also nothing else changed in that setup just testing kernel 4.17.
>>>>
>>>>
>>>>
>>>> That has nothing TODO with the driver nor the original bug you reported.
>>>> The
>>>> problem is that SME is active and that is currently not supported at all
>>>> with a that hardware.
>>>
>>>
>>> Ok .. so are we playing now kernel an AMD Hardware roulette on each
>>> release ?
>>>
>>> SME was like this in kernel 4.16.x here and all worked.
>>
>>
>> If that is true, again please bisect which commit broke it.
>>
>> All the reports I've seen before this indicated that at least amdgpu has
>> never worked with SME (which BTW doesn't mean it's never going to work or
>> that we don't want to support it, just that as far as we know it's currently
>> not working).
>
>
> At least in theory it should work when we use the coherent DMA allocator.
>
> When that really worked before, so the most likely commit which broke this
> is:
>
> commit fd5fd480dd8fe4910546e7b080b3ae345e57fe9f
> Author: Chunming Zhou <david1.zhou@....com>
> Date:   Fri Feb 9 10:44:09 2018 +0800
>
>     drm/amdgpu: only enable swiotlb alloc when need v2
>
>     get the max io mapping address of system memory to see if it is over
>     our card accessing range.
>     v2: move checking later
>
>     Signed-off-by: Chunming Zhou <david1.zhou@....com>
>     Reviewed-by: Monk Liu <monk.liu@....com>
>     Reviewed-by: Christian König <christian.koenig@....com>
>     Signed-off-by: Alex Deucher <alexander.deucher@....com>
>
> Currently looking into how we could somehow improve this detection.

Is not this one , I've build an kernel with this reverted.

I'll do an bisect tonight or tomorrow.

>
> Regards,
> Christian.