Bug 105038

Summary: slight lags in youtube video 1080p since a change in kernel 4.15 related to drm/ttm
Product: DRI Reporter: Barto <mister.freeman>
Component: DRM/RadeonAssignee: Default DRI bug account <dri-devel>
Status: RESOLVED MOVED QA Contact:
Severity: normal    
Priority: medium    
Version: XOrg git   
Hardware: Other   
OS: All   
Whiteboard:
i915 platform: i915 features:
Attachments:
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Description Barto 2018-02-11 01:47:07 UTC 
Created attachment 137264 [details]
dmesg

Hello,

I have a radeon HD4650 pcie, I use the radeon driver,

since a new algorithm for drm/ttm introduced in kernel 4.15.x then I notice a performance loss in video playback, especially when the format is 1080p ( for example youtube video ), some lags are visible ( for example travelling images, vertical scroll of the credits in a video ),

the bug has been introduced since this commit :

commit 648bc3574716400acc06f99915815f80d9563783
Author: Christian König <christian.koenig@amd.com>
Date:   Thu Jul 6 09:59:43 2017 +0200

    drm/ttm: add transparent huge page support for DMA allocations v2
    
    Try to allocate huge pages when it makes sense.
    
    v2: fix comment and use ifdef
    
    Signed-off-by: Christian König <christian.koenig@amd.com>
    Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
    Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

reverting this patch solves the bug,

I have created a bug report in kernel's bugzilla :
https://bugzilla.kernel.org/show_bug.cgi?id=198511

Christian König advices me to open a bug report here for drm/radeon,

I have filmed my screen in order to demonstrate the effect of this bug, you can see my video here :

https://www.youtube.com/watch?v=YqtleU5YBlA
Comment 1 Barto 2018-02-11 01:47:45 UTC 
Created attachment 137265 [details]
glx info
Comment 2 Martin Peres 2019-11-19 09:31:56 UTC 
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