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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [i915][SKL] Headless mode media transcoding is 20-30% slower comparing to connected monitor use case"
href="https://bugs.freedesktop.org/show_bug.cgi?id=100572">100572</a>
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<th>Summary</th>
<td>[i915][SKL] Headless mode media transcoding is 20-30% slower comparing to connected monitor use case
</td>
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<th>Product</th>
<td>DRI
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>Other
</td>
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<th>OS</th>
<td>Linux (All)
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>major
</td>
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>DRM/Intel
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<th>Assignee</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<th>Reporter</th>
<td>dmitry.v.rogozhkin@intel.com
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<th>QA Contact</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<th>CC</th>
<td>intel-gfx-bugs@lists.freedesktop.org
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<pre>Running single media transcoding workload with yamitranscode in headless mode
and with connected monitor gives the following results (4 consequent runs):
# <elapsed time>;<user-space time>;<kernel-space time>;<CPU%>
# connected monitor:
18.41;3.54;3.29;37%
17.09;3.53;3.08;38%
18.29;3.55;3.06;36%
17.06;3.55;3.04;38%
# headless:
25.86;3.55;3.38;26%
22.40;3.53;3.35;30%
23.51;3.56;3.28;29%
22.33;3.55;3.31;30%
So, headless mode is ~25% slower. Mind that issue disappears in headless mode
if the following will be done:
echo on | sudo tee /sys/class/drm/card0-HDMI-A-1/status
Command line used to reproduce:
yamitranscode \
-i 1920x1080p_29.97_10mb_h264_cabac.264 \
-o out.264 \
-W 1920 -H 1080 \
-c AVC \
-ipperiod 1 \
-intraperiod 30 \
--rcmode CBR \
-b 5000
System configuration used:
- SKL NUC6i7KYK (Scull Canyon)
- CPU Turbo OFF in BIOS
- CentOS 7.3 x64, minimal
- cmdline options: intel_pstate=disable i915.enable_rc6=0
intel_idle.max_cstate=1
- Pinned frequency settings:
cpupower frequency-set --governor performance
cpupower frequency-set --min 2000000
cpupower frequency-set --max 2000000
echo 700 > /sys/class/drm/card0/gt_min_freq_mhz
echo 700 > /sys/class/drm/card0/gt_max_freq_mhz
echo 700 > /sys/class/drm/card0/gt_boost_freq_mhz
- Linux kernel built from drm-tip taken at March 10 2017:
commit 2095bbc9d234d71fa44fd9181597431e2653058c
Author: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>>
Date: Fri Mar 10 15:03:46 2017 +0000
drm-tip: 2017y-03m-10d-15h-03m-17s UTC integration manifest</pre>
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