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    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - slight lags in youtube video 1080p since a change in kernel 4.15 related to drm/ttm"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=105038">105038</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>slight lags in youtube video 1080p since a change in kernel 4.15 related to drm/ttm
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>DRI
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>XOrg git
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Other
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>medium
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>DRM/Radeon
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>dri-devel@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>mister.freeman@laposte.net
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=137264" name="attach_137264" title="dmesg">attachment 137264</a> <a href="attachment.cgi?id=137264&action=edit" title="dmesg">[details]</a></span>
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 <<a href="mailto:christian.koenig@amd.com">christian.koenig@amd.com</a>>
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 <<a href="mailto:christian.koenig@amd.com">christian.koenig@amd.com</a>>
    Reviewed-by: Felix Kuehling <<a href="mailto:Felix.Kuehling@amd.com">Felix.Kuehling@amd.com</a>>
    Signed-off-by: Alex Deucher <<a href="mailto:alexander.deucher@amd.com">alexander.deucher@amd.com</a>>

reverting this patch solves the bug,

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

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 :

<a href="https://www.youtube.com/watch?v=YqtleU5YBlA">https://www.youtube.com/watch?v=YqtleU5YBlA</a></pre>
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