[Bug 100572] New: [i915][SKL] Headless mode media transcoding is 20-30% slower comparing to connected monitor use case

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=100572

            Bug ID: 100572
           Summary: [i915][SKL] Headless mode media transcoding is 20-30%
                    slower comparing to connected monitor use case
           Product: DRI
           Version: unspecified
          Hardware: Other
                OS: Linux (All)
            Status: NEW
          Severity: major
          Priority: medium
         Component: DRM/Intel
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: dmitry.v.rogozhkin at intel.com
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
                CC: intel-gfx-bugs at lists.freedesktop.org

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 <chris at chris-wilson.co.uk>
Date:   Fri Mar 10 15:03:46 2017 +0000

    drm-tip: 2017y-03m-10d-15h-03m-17s UTC integration manifest

-- 
You are receiving this mail because:
You are the assignee for the bug.
You are the QA Contact for the bug.
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/intel-gfx-bugs/attachments/20170405/26187823/attachment.html>