linux-kernel - Re: [PATCH 2/2] drm/ttm: Use pr_debug for all output from ttm_bo

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Date:   Thu, 6 Dec 2018 10:38:40 +0100
From:   Michel Dänzer <michel@...nzer.net>
To:     "Koenig, Christian" <Christian.Koenig@....com>,
        "Zhang, Jerry" <Jerry.Zhang@....com>,
        "Huang, Ray" <Ray.Huang@....com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH 2/2] drm/ttm: Use pr_debug for all output from
 ttm_bo_evict

On 2018-12-06 10:33 a.m., Koenig, Christian wrote:
> Am 06.12.18 um 10:09 schrieb Michel Dänzer:
>> On 2018-12-06 3:43 a.m., Zhang, Jerry(Junwei) wrote:
>>> On 12/6/18 12:56 AM, Michel Dänzer wrote:
>>>> From: Michel Dänzer <michel.daenzer@....com>
>>>>
>>>> All the output is related, so it should all be printed the same way.
>>>> Some of it was using pr_debug, but some of it appeared in dmesg by
>>>> default. The caller should handle failure, so there's no need to spam
>>>> dmesg with potentially quite a lot of output by default.
>>>>
>>>> Signed-off-by: Michel Dänzer <michel.daenzer@....com>
>>> Sounds reasonable, but personally prefer to show error when some
>>> vital incident happens, e.g. no memory on eviction.
>> The amdgpu driver still prints these in that case:
>>
>>   [drm:amdgpu_cs_ioctl [amdgpu]] *ERROR* amdgpu_cs_list_validate(validated) failed.
>>   [drm:amdgpu_cs_ioctl [amdgpu]] *ERROR* Not enough memory for command submission!
>>
>> That's plenty as far as I'm concerned. :)
> 
> Yeah, but in this case I would rather make the amdgpu messages debug 
> level and leave the TTM meassages on error level.

That makes no sense to me.

The amdgpu messages have some value for normal users / bug reports,
indicating that something isn't going quite as planned.

The TTM messages are orders of magnitude longer, and are basically noise
for a normal user.

Seems like a no-brainer to me which of these should be visible by default.


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