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

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Message-ID: <50899531-c8ea-6562-f7f3-593481bcef60@gmail.com>
Date:   Thu, 6 Dec 2018 10:49:58 +0100
From:   Christian König <ckoenig.leichtzumerken@...il.com>
To:     "Zhang, Jerry(Junwei)" <Jerry.Zhang@....com>,
        "Koenig, Christian" <Christian.Koenig@....com>,
        Michel Dänzer <michel@...nzer.net>,
        "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

Am 06.12.18 um 10:39 schrieb Zhang, Jerry(Junwei):
> On 12/6/18 5:33 PM, 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 from cs submit, perhaps it may come from other places by 
> ttm_bo_evict_mm().
> Is that right? Christian.

Yeah, exactly my thinking as well. When we silence the TTM messages we 
might miss those cases.

Additional to that other drivers using TTM might not have those messages 
either.

If TTM is to noisy we should use ratelimit and/or reduce the number and 
size of the warning messages.

A simple "Warning, I ran out of memory during eviction!" should do.

Regards,
Christian.

>
> Regards,
> Jerry
>>>
>>> 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.
>>
>> Christian.
>
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