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

        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - [IVB bisected]x11perf performance reduced by 40%"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=62710">62710</a>
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>intel-gfx-bugs@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[IVB bisected]x11perf performance reduced by 40%
          </td>
        </tr>

        <tr>
          <th>QA Contact</th>
          <td>intel-gfx-bugs@lists.freedesktop.org
          </td>
        </tr>

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

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>mengmeng.meng@intel.com
          </td>
        </tr>

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

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

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

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

        <tr>
          <th>Product</th>
          <td>DRI
          </td>
        </tr></table>
      <p>
        <div>
        <pre>System Environment:       
--------------------------
Platform:IVB
Libdrm: (master)libdrm-2.4.42-7-g36a2daad2416ad55a859c483b0d7ed93a5eff6e0
Mesa:   (9.1)e6616948b74531eae3137585b3ae35a1fc0f8174
Xserver:(server-1.13-branch)xorg-server-1.13.3
Xf86_video_intel:(master)2.21.5-1-g9f8e86800345d19785eae2dd2099dd7d61a7a3b3
Kernel: (drm-intel-fixes) c12aba5aa0e60b7947bc8b6ea25ef55c4acf81a4

Bug detailed description:
-----------------------------
x11perf performance reduced by 40% on IVB. The problem exists on both xinit and
gnome-session. It's kernel regression, by bisected show 3b4f819d5eac94ba8fe5 is
the first bad commit.

commit 3b4f819d5eac94ba8fe5e8c061f6dabfe8d7b22c
Author: Takashi Iwai <<a href="mailto:tiwai@suse.de">tiwai@suse.de</a>>
Date:   Mon Mar 11 18:40:16 2013 +0100
    Revert "drm/i915: try to train DP even harder"

Performance data
-------------------
x11perf -aa10text on IVB.
                   gnome-session         xinit               
good(3118a)        3620000.0/sec        4230000.0/sec       
bad(3b4f81)        2300000.0/sec        2480000.0/sec

Reproduce steps:
----------------------------
1, xinit&
2, vblank_mode=0 x11perf -aa10text</pre>
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