[igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval

[igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval

[Anand Moon]

Using confidence interval formula accuracy is estimates approximately
at 95% when {X} is the average of a sample of size n.
Use this confidence interval formula as used in statistics
to estimate the accuracy.

Cc: Dorota Czaplejewicz <dorota.czaplejewicz@collabora.co.uk>
Signed-off-by: Anand Moon <anandx.ram.moon@intel.com>
---
See below link.
https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule#Cumulative_distribution_function
---
 tests/kms_setmode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/kms_setmode.c b/tests/kms_setmode.c
index 92f3ead2..58814a13 100644
--- a/tests/kms_setmode.c
+++ b/tests/kms_setmode.c
@@ -494,7 +494,7 @@ static void check_timings(int crtc_idx, const drmModeModeInfo *kmode)
 	 * which depend on timing, giving the lowest acceptable MTBF of 5.6s
 	 * for 60Hz sampling rate.
 	 */
-	accuracy = 3. * stddev;
+	accuracy = 3. * stddev / sqrt(CALIBRATE_TS_STEPS);
 
 	igt_info("Expected frametime: %.0fus; measured %.1fus +- %.3fus accuracy %.2f%% [%.2f scanlines]\n",
 		 expected, mean, stddev,
-- 
2.25.1

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[igt-dev] ✓ Fi.CI.BAT: success for tests/kms_setmode: basic Improve accuracy with using of confidence interval (rev2)

[Patchwork]

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== Series Details ==

Series: tests/kms_setmode: basic Improve accuracy with using of confidence interval (rev2)
URL   : https://patchwork.freedesktop.org/series/83411/
State : success

== Summary ==

CI Bug Log - changes from CI_DRM_9250 -> IGTPW_5120
====================================================

Summary
-------

  **SUCCESS**

  No regressions found.

  External URL: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/index.html

Known issues
------------

  Here are the changes found in IGTPW_5120 that come from known issues:

### IGT changes ###

#### Issues hit ####

  * igt@i915_module_load@reload:
    - fi-icl-u2:          [PASS][1] -> [DMESG-WARN][2] ([i915#1982]) +1 similar issue
   [1]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/fi-icl-u2/igt@i915_module_load@reload.html
   [2]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/fi-icl-u2/igt@i915_module_load@reload.html
    - fi-icl-y:           [PASS][3] -> [DMESG-WARN][4] ([i915#1982])
   [3]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/fi-icl-y/igt@i915_module_load@reload.html
   [4]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/fi-icl-y/igt@i915_module_load@reload.html

  * igt@i915_pm_rpm@module-reload:
    - fi-skl-lmem:        [PASS][5] -> [DMESG-WARN][6] ([i915#2605])
   [5]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/fi-skl-lmem/igt@i915_pm_rpm@module-reload.html
   [6]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/fi-skl-lmem/igt@i915_pm_rpm@module-reload.html

  * igt@i915_selftest@live@gt_timelines:
    - fi-apl-guc:         [PASS][7] -> [INCOMPLETE][8] ([i915#1635])
   [7]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/fi-apl-guc/igt@i915_selftest@live@gt_timelines.html
   [8]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/fi-apl-guc/igt@i915_selftest@live@gt_timelines.html

  * igt@kms_cursor_legacy@basic-busy-flip-before-cursor-atomic:
    - fi-byt-j1900:       [PASS][9] -> [DMESG-WARN][10] ([i915#1982])
   [9]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/fi-byt-j1900/igt@kms_cursor_legacy@basic-busy-flip-before-cursor-atomic.html
   [10]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/fi-byt-j1900/igt@kms_cursor_legacy@basic-busy-flip-before-cursor-atomic.html

  
#### Possible fixes ####

  * igt@core_hotunplug@unbind-rebind:
    - fi-icl-y:           [DMESG-WARN][11] ([i915#1982]) -> [PASS][12]
   [11]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/fi-icl-y/igt@core_hotunplug@unbind-rebind.html
   [12]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/fi-icl-y/igt@core_hotunplug@unbind-rebind.html

  * igt@kms_chamelium@dp-crc-fast:
    - fi-cml-u2:          [DMESG-WARN][13] ([i915#1982]) -> [PASS][14]
   [13]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/fi-cml-u2/igt@kms_chamelium@dp-crc-fast.html
   [14]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/fi-cml-u2/igt@kms_chamelium@dp-crc-fast.html

  * igt@kms_cursor_legacy@basic-busy-flip-before-cursor-atomic:
    - fi-apl-guc:         [DMESG-WARN][15] ([i915#1635] / [i915#1982]) -> [PASS][16]
   [15]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/fi-apl-guc/igt@kms_cursor_legacy@basic-busy-flip-before-cursor-atomic.html
   [16]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/fi-apl-guc/igt@kms_cursor_legacy@basic-busy-flip-before-cursor-atomic.html

  
  {name}: This element is suppressed. This means it is ignored when computing
          the status of the difference (SUCCESS, WARNING, or FAILURE).

  [i915#1635]: https://gitlab.freedesktop.org/drm/intel/issues/1635
  [i915#1982]: https://gitlab.freedesktop.org/drm/intel/issues/1982
  [i915#2411]: https://gitlab.freedesktop.org/drm/intel/issues/2411
  [i915#2605]: https://gitlab.freedesktop.org/drm/intel/issues/2605


Participating hosts (43 -> 39)
------------------------------

  Missing    (4): fi-ilk-m540 fi-bsw-cyan fi-bdw-samus fi-hsw-4200u 


Build changes
-------------

  * CI: CI-20190529 -> None
  * IGT: IGT_5830 -> IGTPW_5120

  CI-20190529: 20190529
  CI_DRM_9250: 0ddbbf768a932ea9ca82a5872fd83977e27347c0 @ git://anongit.freedesktop.org/gfx-ci/linux
  IGTPW_5120: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/index.html
  IGT_5830: 12d370cb57e0cfcb781c87ad9e15e68b17a1f41f @ git://anongit.freedesktop.org/xorg/app/intel-gpu-tools

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/index.html

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[igt-dev] ✗ Fi.CI.IGT: failure for tests/kms_setmode: basic Improve accuracy with using of confidence interval (rev2)

[Patchwork]

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== Series Details ==

Series: tests/kms_setmode: basic Improve accuracy with using of confidence interval (rev2)
URL   : https://patchwork.freedesktop.org/series/83411/
State : failure

== Summary ==

CI Bug Log - changes from CI_DRM_9250_full -> IGTPW_5120_full
====================================================

Summary
-------

  **FAILURE**

  Serious unknown changes coming with IGTPW_5120_full absolutely need to be
  verified manually.
  
  If you think the reported changes have nothing to do with the changes
  introduced in IGTPW_5120_full, please notify your bug team to allow them
  to document this new failure mode, which will reduce false positives in CI.

  External URL: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/index.html

Possible new issues
-------------------

  Here are the unknown changes that may have been introduced in IGTPW_5120_full:

### IGT changes ###

#### Possible regressions ####

  * igt@gem_eio@in-flight-suspend:
    - shard-hsw:          [PASS][1] -> [DMESG-WARN][2]
   [1]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-hsw1/igt@gem_eio@in-flight-suspend.html
   [2]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-hsw4/igt@gem_eio@in-flight-suspend.html
    - shard-glk:          [PASS][3] -> [DMESG-WARN][4]
   [3]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-glk5/igt@gem_eio@in-flight-suspend.html
   [4]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-glk6/igt@gem_eio@in-flight-suspend.html

  * igt@gen7_exec_parse@chained-batch:
    - shard-hsw:          [PASS][5] -> [FAIL][6]
   [5]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-hsw1/igt@gen7_exec_parse@chained-batch.html
   [6]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-hsw6/igt@gen7_exec_parse@chained-batch.html

  
Known issues
------------

  Here are the changes found in IGTPW_5120_full that come from known issues:

### IGT changes ###

#### Issues hit ####

  * igt@gem_eio@in-flight-suspend:
    - shard-kbl:          [PASS][7] -> [INCOMPLETE][8] ([i915#155])
   [7]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-kbl3/igt@gem_eio@in-flight-suspend.html
   [8]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-kbl4/igt@gem_eio@in-flight-suspend.html
    - shard-apl:          [PASS][9] -> [INCOMPLETE][10] ([i915#1635])
   [9]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-apl7/igt@gem_eio@in-flight-suspend.html
   [10]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-apl6/igt@gem_eio@in-flight-suspend.html

  * igt@gem_exec_whisper@basic-forked:
    - shard-glk:          [PASS][11] -> [DMESG-WARN][12] ([i915#118] / [i915#95])
   [11]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-glk8/igt@gem_exec_whisper@basic-forked.html
   [12]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-glk7/igt@gem_exec_whisper@basic-forked.html

  * igt@gem_partial_pwrite_pread@writes-after-reads-uncached:
    - shard-snb:          [PASS][13] -> [INCOMPLETE][14] ([i915#82])
   [13]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-snb7/igt@gem_partial_pwrite_pread@writes-after-reads-uncached.html
   [14]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-snb4/igt@gem_partial_pwrite_pread@writes-after-reads-uncached.html

  * igt@i915_pm_backlight@fade_with_suspend:
    - shard-iclb:         [PASS][15] -> [INCOMPLETE][16] ([i915#1185])
   [15]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-iclb1/igt@i915_pm_backlight@fade_with_suspend.html
   [16]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-iclb4/igt@i915_pm_backlight@fade_with_suspend.html

  * igt@i915_pm_rpm@sysfs-read:
    - shard-iclb:         [PASS][17] -> [SKIP][18] ([i915#579])
   [17]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-iclb6/igt@i915_pm_rpm@sysfs-read.html
   [18]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-iclb2/igt@i915_pm_rpm@sysfs-read.html
    - shard-apl:          [PASS][19] -> [SKIP][20] ([fdo#109271] / [i915#1635])
   [19]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-apl2/igt@i915_pm_rpm@sysfs-read.html
   [20]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-apl6/igt@i915_pm_rpm@sysfs-read.html
    - shard-glk:          [PASS][21] -> [SKIP][22] ([fdo#109271])
   [21]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-glk9/igt@i915_pm_rpm@sysfs-read.html
   [22]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-glk2/igt@i915_pm_rpm@sysfs-read.html
    - shard-kbl:          [PASS][23] -> [SKIP][24] ([fdo#109271])
   [23]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-kbl7/igt@i915_pm_rpm@sysfs-read.html
   [24]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-kbl7/igt@i915_pm_rpm@sysfs-read.html

  * igt@kms_cursor_edge_walk@pipe-b-64x64-left-edge:
    - shard-apl:          [PASS][25] -> [DMESG-WARN][26] ([i915#1635] / [i915#1982]) +5 similar issues
   [25]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-apl3/igt@kms_cursor_edge_walk@pipe-b-64x64-left-edge.html
   [26]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-apl7/igt@kms_cursor_edge_walk@pipe-b-64x64-left-edge.html
    - shard-tglb:         [PASS][27] -> [DMESG-WARN][28] ([i915#1982]) +3 similar issues
   [27]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-tglb2/igt@kms_cursor_edge_walk@pipe-b-64x64-left-edge.html
   [28]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-tglb8/igt@kms_cursor_edge_walk@pipe-b-64x64-left-edge.html

  * igt@kms_flip@2x-flip-vs-panning@ab-vga1-hdmi-a1:
    - shard-hsw:          [PASS][29] -> [DMESG-WARN][30] ([i915#1982]) +1 similar issue
   [29]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-hsw1/igt@kms_flip@2x-flip-vs-panning@ab-vga1-hdmi-a1.html
   [30]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-hsw4/igt@kms_flip@2x-flip-vs-panning@ab-vga1-hdmi-a1.html

  * igt@kms_flip@flip-vs-expired-vblank-interruptible@a-edp1:
    - shard-tglb:         [PASS][31] -> [FAIL][32] ([i915#2598])
   [31]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-tglb2/igt@kms_flip@flip-vs-expired-vblank-interruptible@a-edp1.html
   [32]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-tglb7/igt@kms_flip@flip-vs-expired-vblank-interruptible@a-edp1.html

  * igt@kms_flip@plain-flip-fb-recreate@d-edp1:
    - shard-tglb:         [PASS][33] -> [FAIL][34] ([i915#2122])
   [33]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-tglb8/igt@kms_flip@plain-flip-fb-recreate@d-edp1.html
   [34]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-tglb1/igt@kms_flip@plain-flip-fb-recreate@d-edp1.html

  * igt@kms_frontbuffer_tracking@fbc-1p-rte:
    - shard-glk:          [PASS][35] -> [DMESG-WARN][36] ([i915#1982]) +6 similar issues
   [35]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-glk8/igt@kms_frontbuffer_tracking@fbc-1p-rte.html
   [36]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-glk2/igt@kms_frontbuffer_tracking@fbc-1p-rte.html

  * igt@kms_frontbuffer_tracking@fbc-rgb565-draw-mmap-gtt:
    - shard-snb:          [PASS][37] -> [FAIL][38] ([i915#2546])
   [37]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-snb7/igt@kms_frontbuffer_tracking@fbc-rgb565-draw-mmap-gtt.html
   [38]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-snb4/igt@kms_frontbuffer_tracking@fbc-rgb565-draw-mmap-gtt.html

  * igt@kms_psr@psr2_primary_mmap_cpu:
    - shard-iclb:         [PASS][39] -> [SKIP][40] ([fdo#109441]) +2 similar issues
   [39]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-iclb2/igt@kms_psr@psr2_primary_mmap_cpu.html
   [40]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-iclb8/igt@kms_psr@psr2_primary_mmap_cpu.html

  * igt@kms_universal_plane@universal-plane-gen9-features-pipe-a:
    - shard-kbl:          [PASS][41] -> [DMESG-WARN][42] ([i915#1982]) +6 similar issues
   [41]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-kbl7/igt@kms_universal_plane@universal-plane-gen9-features-pipe-a.html
   [42]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-kbl3/igt@kms_universal_plane@universal-plane-gen9-features-pipe-a.html

  * igt@perf@invalid-oa-format-id:
    - shard-kbl:          [PASS][43] -> [SKIP][44] ([fdo#109271] / [i915#1354])
   [43]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-kbl1/igt@perf@invalid-oa-format-id.html
   [44]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-kbl2/igt@perf@invalid-oa-format-id.html
    - shard-hsw:          [PASS][45] -> [SKIP][46] ([fdo#109271]) +1 similar issue
   [45]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-hsw6/igt@perf@invalid-oa-format-id.html
   [46]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-hsw6/igt@perf@invalid-oa-format-id.html
    - shard-tglb:         [PASS][47] -> [SKIP][48] ([i915#1354])
   [47]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-tglb2/igt@perf@invalid-oa-format-id.html
   [48]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-tglb8/igt@perf@invalid-oa-format-id.html
    - shard-iclb:         [PASS][49] -> [SKIP][50] ([i915#1354])
   [49]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-iclb1/igt@perf@invalid-oa-format-id.html
   [50]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-iclb2/igt@perf@invalid-oa-format-id.html
    - shard-glk:          [PASS][51] -> [SKIP][52] ([fdo#109271] / [i915#1354])
   [51]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-glk8/igt@perf@invalid-oa-format-id.html
   [52]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-glk9/igt@perf@invalid-oa-format-id.html
    - shard-apl:          [PASS][53] -> [SKIP][54] ([fdo#109271] / [i915#1354] / [i915#1635])
   [53]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-apl4/igt@perf@invalid-oa-format-id.html
   [54]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-apl2/igt@perf@invalid-oa-format-id.html

  * igt@perf_pmu@module-unload:
    - shard-iclb:         [PASS][55] -> [DMESG-WARN][56] ([i915#1982]) +1 similar issue
   [55]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-iclb8/igt@perf_pmu@module-unload.html
   [56]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-iclb7/igt@perf_pmu@module-unload.html

  
#### Possible fixes ####

  * igt@gem_exec_reloc@basic-many-active@rcs0:
    - shard-glk:          [FAIL][57] ([i915#2389]) -> [PASS][58]
   [57]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-glk2/igt@gem_exec_reloc@basic-many-active@rcs0.html
   [58]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-glk3/igt@gem_exec_reloc@basic-many-active@rcs0.html

  * igt@gem_partial_pwrite_pread@writes-after-reads-uncached:
    - shard-hsw:          [FAIL][59] ([i915#1888]) -> [PASS][60]
   [59]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-hsw1/igt@gem_partial_pwrite_pread@writes-after-reads-uncached.html
   [60]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-hsw6/igt@gem_partial_pwrite_pread@writes-after-reads-uncached.html

  * igt@i915_pm_rpm@pm-tiling:
    - shard-hsw:          [SKIP][61] ([fdo#109271]) -> [PASS][62] +2 similar issues
   [61]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-hsw4/igt@i915_pm_rpm@pm-tiling.html
   [62]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-hsw6/igt@i915_pm_rpm@pm-tiling.html
    - shard-kbl:          [SKIP][63] ([fdo#109271]) -> [PASS][64] +1 similar issue
   [63]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-kbl6/igt@i915_pm_rpm@pm-tiling.html
   [64]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-kbl2/igt@i915_pm_rpm@pm-tiling.html
    - shard-apl:          [SKIP][65] ([fdo#109271] / [i915#1635]) -> [PASS][66] +1 similar issue
   [65]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-apl6/igt@i915_pm_rpm@pm-tiling.html
   [66]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-apl7/igt@i915_pm_rpm@pm-tiling.html
    - shard-glk:          [SKIP][67] ([fdo#109271]) -> [PASS][68] +1 similar issue
   [67]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-glk1/igt@i915_pm_rpm@pm-tiling.html
   [68]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-glk5/igt@i915_pm_rpm@pm-tiling.html
    - shard-iclb:         [SKIP][69] ([i915#579]) -> [PASS][70]
   [69]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-iclb8/igt@i915_pm_rpm@pm-tiling.html
   [70]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-iclb8/igt@i915_pm_rpm@pm-tiling.html

  * igt@i915_suspend@fence-restore-untiled:
    - shard-kbl:          [DMESG-WARN][71] ([i915#180]) -> [PASS][72]
   [71]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-kbl2/igt@i915_suspend@fence-restore-untiled.html
   [72]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-kbl6/igt@i915_suspend@fence-restore-untiled.html

  * igt@kms_atomic_transition@plane-use-after-nonblocking-unbind-fencing@vga-1-pipe-a:
    - shard-hsw:          [DMESG-WARN][73] ([i915#1982]) -> [PASS][74] +2 similar issues
   [73]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-hsw6/igt@kms_atomic_transition@plane-use-after-nonblocking-unbind-fencing@vga-1-pipe-a.html
   [74]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-hsw1/igt@kms_atomic_transition@plane-use-after-nonblocking-unbind-fencing@vga-1-pipe-a.html

  * igt@kms_busy@basic-flip-pipe-b:
    - shard-tglb:         [DMESG-WARN][75] ([i915#1982]) -> [PASS][76] +2 similar issues
   [75]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-tglb7/igt@kms_busy@basic-flip-pipe-b.html
   [76]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-tglb8/igt@kms_busy@basic-flip-pipe-b.html

  * igt@kms_draw_crc@draw-method-xrgb2101010-render-ytiled:
    - shard-kbl:          [DMESG-WARN][77] ([i915#1982]) -> [PASS][78] +4 similar issues
   [77]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-kbl1/igt@kms_draw_crc@draw-method-xrgb2101010-render-ytiled.html
   [78]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-kbl7/igt@kms_draw_crc@draw-method-xrgb2101010-render-ytiled.html

  * igt@kms_draw_crc@draw-method-xrgb8888-render-untiled:
    - shard-glk:          [DMESG-WARN][79] ([i915#1982]) -> [PASS][80] +6 similar issues
   [79]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-glk2/igt@kms_draw_crc@draw-method-xrgb8888-render-untiled.html
   [80]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-glk7/igt@kms_draw_crc@draw-method-xrgb8888-render-untiled.html

  * igt@kms_frontbuffer_tracking@fbc-rgb101010-draw-render:
    - shard-snb:          [FAIL][81] ([i915#2546]) -> [PASS][82]
   [81]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-snb7/igt@kms_frontbuffer_tracking@fbc-rgb101010-draw-render.html
   [82]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-snb2/igt@kms_frontbuffer_tracking@fbc-rgb101010-draw-render.html

  * igt@kms_frontbuffer_tracking@psr-1p-offscren-pri-indfb-draw-blt:
    - shard-iclb:         [DMESG-WARN][83] ([i915#1982]) -> [PASS][84]
   [83]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-iclb6/igt@kms_frontbuffer_tracking@psr-1p-offscren-pri-indfb-draw-blt.html
   [84]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-iclb5/igt@kms_frontbuffer_tracking@psr-1p-offscren-pri-indfb-draw-blt.html

  * igt@kms_psr@psr2_sprite_plane_move:
    - shard-iclb:         [SKIP][85] ([fdo#109441]) -> [PASS][86] +1 similar issue
   [85]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-iclb3/igt@kms_psr@psr2_sprite_plane_move.html
   [86]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-iclb2/igt@kms_psr@psr2_sprite_plane_move.html

  * igt@kms_psr@suspend:
    - shard-iclb:         [INCOMPLETE][87] ([i915#1185]) -> [PASS][88]
   [87]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-iclb6/igt@kms_psr@suspend.html
   [88]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-iclb4/igt@kms_psr@suspend.html

  * igt@kms_setmode@basic:
    - shard-tglb:         [FAIL][89] ([i915#31]) -> [PASS][90]
   [89]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-tglb7/igt@kms_setmode@basic.html
   [90]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-tglb5/igt@kms_setmode@basic.html
    - shard-glk:          [FAIL][91] ([i915#31]) -> [PASS][92]
   [91]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-glk4/igt@kms_setmode@basic.html
   [92]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-glk8/igt@kms_setmode@basic.html
    - shard-hsw:          [FAIL][93] ([i915#31]) -> [PASS][94]
   [93]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-hsw6/igt@kms_setmode@basic.html
   [94]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-hsw6/igt@kms_setmode@basic.html
    - shard-kbl:          [FAIL][95] ([i915#31]) -> [PASS][96]
   [95]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-kbl4/igt@kms_setmode@basic.html
   [96]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-kbl6/igt@kms_setmode@basic.html
    - shard-iclb:         [FAIL][97] ([i915#31]) -> [PASS][98]
   [97]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-iclb4/igt@kms_setmode@basic.html
   [98]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-iclb3/igt@kms_setmode@basic.html

  * igt@kms_sysfs_edid_timing:
    - shard-hsw:          [FAIL][99] ([IGT#2]) -> [PASS][100]
   [99]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-hsw1/igt@kms_sysfs_edid_timing.html
   [100]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-hsw1/igt@kms_sysfs_edid_timing.html

  * igt@kms_vblank@pipe-c-accuracy-idle:
    - shard-apl:          [DMESG-WARN][101] ([i915#1635] / [i915#1982]) -> [PASS][102] +5 similar issues
   [101]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-apl8/igt@kms_vblank@pipe-c-accuracy-idle.html
   [102]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-apl2/igt@kms_vblank@pipe-c-accuracy-idle.html

  * igt@perf@non-system-wide-paranoid:
    - shard-apl:          [SKIP][103] ([fdo#109271] / [i915#1354] / [i915#1635]) -> [PASS][104]
   [103]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-apl8/igt@perf@non-system-wide-paranoid.html
   [104]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-apl6/igt@perf@non-system-wide-paranoid.html
    - shard-glk:          [SKIP][105] ([fdo#109271] / [i915#1354]) -> [PASS][106]
   [105]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-glk4/igt@perf@non-system-wide-paranoid.html
   [106]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-glk2/igt@perf@non-system-wide-paranoid.html
    - shard-iclb:         [SKIP][107] ([i915#1354]) -> [PASS][108]
   [107]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-iclb6/igt@perf@non-system-wide-paranoid.html
   [108]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-iclb4/igt@perf@non-system-wide-paranoid.html
    - shard-kbl:          [SKIP][109] ([fdo#109271] / [i915#1354]) -> [PASS][110]
   [109]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-kbl6/igt@perf@non-system-wide-paranoid.html
   [110]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-kbl7/igt@perf@non-system-wide-paranoid.html
    - shard-tglb:         [SKIP][111] ([i915#1354]) -> [PASS][112]
   [111]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-tglb1/igt@perf@non-system-wide-paranoid.html
   [112]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-tglb3/igt@perf@non-system-wide-paranoid.html

  * igt@perf@polling-parameterized:
    - shard-hsw:          [FAIL][113] ([i915#1542]) -> [PASS][114]
   [113]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-hsw6/igt@perf@polling-parameterized.html
   [114]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-hsw6/igt@perf@polling-parameterized.html

  
#### Warnings ####

  * igt@i915_pm_rpm@dpms-mode-unset-non-lpsp:
    - shard-iclb:         [SKIP][115] ([i915#579]) -> [SKIP][116] ([fdo#110892])
   [115]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-iclb6/igt@i915_pm_rpm@dpms-mode-unset-non-lpsp.html
   [116]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-iclb1/igt@i915_pm_rpm@dpms-mode-unset-non-lpsp.html

  * igt@i915_pm_rpm@pm-tiling:
    - shard-tglb:         [SKIP][117] ([i915#579]) -> [DMESG-WARN][118] ([i915#2411])
   [117]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-tglb8/igt@i915_pm_rpm@pm-tiling.html
   [118]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-tglb5/igt@i915_pm_rpm@pm-tiling.html

  * igt@i915_pm_rpm@sysfs-read:
    - shard-tglb:         [DMESG-WARN][119] ([i915#2411]) -> [SKIP][120] ([i915#579])
   [119]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-tglb6/igt@i915_pm_rpm@sysfs-read.html
   [120]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-tglb3/igt@i915_pm_rpm@sysfs-read.html

  * igt@kms_vblank@pipe-d-ts-continuation-dpms-suspend:
    - shard-tglb:         [DMESG-WARN][121] ([i915#2411]) -> [INCOMPLETE][122] ([i915#1436] / [i915#1887] / [i915#1982])
   [121]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-tglb3/igt@kms_vblank@pipe-d-ts-continuation-dpms-suspend.html
   [122]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-tglb3/igt@kms_vblank@pipe-d-ts-continuation-dpms-suspend.html

  * igt@runner@aborted:
    - shard-iclb:         [FAIL][123] ([i915#1814]) -> [FAIL][124] ([i915#1814] / [i915#2439])
   [123]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-iclb6/igt@runner@aborted.html
   [124]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-iclb4/igt@runner@aborted.html
    - shard-tglb:         [FAIL][125] ([i915#2439]) -> [FAIL][126] ([i915#1602])
   [125]: https://intel-gfx-ci.01.org/tree/drm-tip/CI_DRM_9250/shard-tglb8/igt@runner@aborted.html
   [126]: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/shard-tglb3/igt@runner@aborted.html

  
  {name}: This element is suppressed. This means it is ignored when computing
          the status of the difference (SUCCESS, WARNING, or FAILURE).

  [IGT#2]: https://gitlab.freedesktop.org/drm/igt-gpu-tools/issues/2
  [fdo#109271]: https://bugs.freedesktop.org/show_bug.cgi?id=109271
  [fdo#109441]: https://bugs.freedesktop.org/show_bug.cgi?id=109441
  [fdo#110892]: https://bugs.freedesktop.org/show_bug.cgi?id=110892
  [i915#118]: https://gitlab.freedesktop.org/drm/intel/issues/118
  [i915#1185]: https://gitlab.freedesktop.org/drm/intel/issues/1185
  [i915#1354]: https://gitlab.freedesktop.org/drm/intel/issues/1354
  [i915#1436]: https://gitlab.freedesktop.org/drm/intel/issues/1436
  [i915#1542]: https://gitlab.freedesktop.org/drm/intel/issues/1542
  [i915#155]: https://gitlab.freedesktop.org/drm/intel/issues/155
  [i915#1602]: https://gitlab.freedesktop.org/drm/intel/issues/1602
  [i915#1635]: https://gitlab.freedesktop.org/drm/intel/issues/1635
  [i915#180]: https://gitlab.freedesktop.org/drm/intel/issues/180
  [i915#1814]: https://gitlab.freedesktop.org/drm/intel/issues/1814
  [i915#1887]: https://gitlab.freedesktop.org/drm/intel/issues/1887
  [i915#1888]: https://gitlab.freedesktop.org/drm/intel/issues/1888
  [i915#1982]: https://gitlab.freedesktop.org/drm/intel/issues/1982
  [i915#2122]: https://gitlab.freedesktop.org/drm/intel/issues/2122
  [i915#2389]: https://gitlab.freedesktop.org/drm/intel/issues/2389
  [i915#2411]: https://gitlab.freedesktop.org/drm/intel/issues/2411
  [i915#2439]: https://gitlab.freedesktop.org/drm/intel/issues/2439
  [i915#2521]: https://gitlab.freedesktop.org/drm/intel/issues/2521
  [i915#2546]: https://gitlab.freedesktop.org/drm/intel/issues/2546
  [i915#2598]: https://gitlab.freedesktop.org/drm/intel/issues/2598
  [i915#31]: https://gitlab.freedesktop.org/drm/intel/issues/31
  [i915#579]: https://gitlab.freedesktop.org/drm/intel/issues/579
  [i915#82]: https://gitlab.freedesktop.org/drm/intel/issues/82
  [i915#95]: https://gitlab.freedesktop.org/drm/intel/issues/95


Participating hosts (11 -> 8)
------------------------------

  Missing    (3): pig-skl-6260u pig-glk-j5005 pig-icl-1065g7 


Build changes
-------------

  * CI: CI-20190529 -> None
  * IGT: IGT_5830 -> IGTPW_5120
  * Piglit: piglit_4509 -> None

  CI-20190529: 20190529
  CI_DRM_9250: 0ddbbf768a932ea9ca82a5872fd83977e27347c0 @ git://anongit.freedesktop.org/gfx-ci/linux
  IGTPW_5120: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/index.html
  IGT_5830: 12d370cb57e0cfcb781c87ad9e15e68b17a1f41f @ git://anongit.freedesktop.org/xorg/app/intel-gpu-tools
  piglit_4509: fdc5a4ca11124ab8413c7988896eec4c97336694 @ git://anongit.freedesktop.org/piglit

== Logs ==

For more details see: https://intel-gfx-ci.01.org/tree/drm-tip/IGTPW_5120/index.html

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Re: [igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval

[Ram Moon, AnandX]

Hi Chris,

-----Original Message-----
From: Chris Wilson <chris@chris-wilson.co.uk> 
Sent: Friday, November 20, 2020 8:36 PM
To: Ram Moon, AnandX <anandx.ram.moon@intel.com>; igt-dev@lists.freedesktop.org
Subject: Re: [igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval

Quoting Ram Moon, AnandX (2020-11-20 09:12:40)
> Hi Chris,
> 
> -----Original Message-----
> From: Ram Moon, AnandX
> Sent: Tuesday, November 3, 2020 11:28 PM
> To: Chris Wilson <chris@chris-wilson.co.uk>; 
> igt-dev@lists.freedesktop.org
> Subject: RE: [igt-dev] [i-g-t] tests/kms_setmode: basic Improve 
> accuracy with using of confidence interval
> 
> Hi Chris,
> 
> Thanks for your review comment.
> 
> -----Original Message-----
> From: Chris Wilson <chris@chris-wilson.co.uk>
> Sent: Tuesday, November 3, 2020 4:19 PM
> To: Ram Moon, AnandX <anandx.ram.moon@intel.com>; 
> igt-dev@lists.freedesktop.org
> Cc: Ram Moon, AnandX <anandx.ram.moon@intel.com>
> Subject: Re: [igt-dev] [i-g-t] tests/kms_setmode: basic Improve 
> accuracy with using of confidence interval
> 
> Quoting Anand Moon (2020-11-02 09:08:36)
> > Using confidence interval formula accuracy is estimates 
> > approximately at 95% when {X} is the average of a sample of size n.
> > Use this confidence interval formula as used in statistics to 
> > estimate the accuracy.
> > 
> > Signed-off-by: Anand Moon <anandx.ram.moon@intel.com>
> > ---
> > See below link.
> > https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule#Cumula
> > ti
> > ve_distribution_function
> > ---
> >  tests/kms_setmode.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/tests/kms_setmode.c b/tests/kms_setmode.c index
> > 92f3ead2..58814a13 100644
> > --- a/tests/kms_setmode.c
> > +++ b/tests/kms_setmode.c
> > @@ -494,7 +494,7 @@ static void check_timings(int crtc_idx, const drmModeModeInfo *kmode)
> >          * which depend on timing, giving the lowest acceptable MTBF of 5.6s
> >          * for 60Hz sampling rate.
> >          */
> > -       accuracy = 3. * stddev;
> > +       accuracy = 3. * stddev / sqrt(CALIBRATE_TS_STEPS);
> 
> Oops, yes, this should be standard error rather than deviation. Could you add igt_stats_get_std_error() so we don't hardcode N?
> -Chris
> 
> Do you want me to rename accuracy to std_error and use stats.n_values instead of CALIBRATE_TS_STEPS I could not find the definition of igt_stats_get_std_error function. 
> 
> -Anand
> 
> Thanks for fixing the code changes.
> 
> Actually above changes fix the issue to improve the accuracy calculations.
> But now I am able to reproduce the original bug using 4K monitors on 5.8.x kernel, See below logs.
> 
>     CRTC[98] [Pipe A] Mode: 3840x2160@60Hz Connectors: DP-2[330] 
> Expected frametime: 16668us; measured 16672.3us +- 1.805us accuracy 
> 0.00% [0.07 scanlines]
> (kms_setmode:14315) CRITICAL: Test assertion failure function check_timings, file ../tests/kms_setmode.c:544:
> (kms_setmode:14315) CRITICAL: Failed assertion: fabs(mean - expected) 
> < 1.718 * stddev
> (kms_setmode:14315) CRITICAL: vblank interval differs from modeline! expected 16667.6us, measured 16672us +- 1.805us, difference 4.7us (2.6 sigma) Stack trace:
>   #0 ../lib/igt_core.c:1734 __igt_fail_assert()
>   #1 ../tests/kms_setmode.c:544 test_one_combination()
>   #2 ../tests/kms_setmode.c:834 __real_main883()
>   #3 ../tests/kms_setmode.c:883 main()
>   #4 ../csu/libc-start.c:342 __libc_start_main()
>   #5 [_start+0x2e]
> Subtest basic failed.
> **** DEBUG ****
>  
> So after in digging into the below comments it turns out that 
> *confidence interval* with respect to standard deviation is calculated 
> with *Cumulative distribution function* (formula)
> 
> As per the Wikipedia table
> For various values of z, the percentage of values expected to lie in and outside the symmetric interval, CI = (−zσ, zσ), are as follows:
> [0] 
> https://en.wikipedia.org/wiki/Standard_deviation#Rules_for_normally_di
> stributed_data
> 
> It turns out that  *3 σ* gives around proportion percentage 99.7300204% which is according to the CI = (−zσ, zσ) table.
> 
> I would like to submit a below patch as this changes fix the overall bug.
> Please share your thought and suggestion on any alternative approach I should try.

You would also have to update the comments as it no longer matches the broaden 90% critical value.

Still debating what is a sensible error rate, but in the meantime I would suggest a different approach: ignore the deviation if it is within a single scanline.

Something like:

-       igt_assert_f(fabs(mean - expected) < 1.718 * stddev,
-                    "vblank interval differs from modeline! expected %.1fus, measured %1.fus +- %.3fus, difference %.1fus (%.1f sigma)\n",
+       igt_assert_f(fabs(mean - expected) < max(line_time(kmode), 1.718 * stddev),
+                    "vblank interval differs from modeline! expected 
+ %.1fus, measured %1.fus +- %.3fus, difference %.1fus (%.1f sigma, %.1f 
+ scanlines)\n",
                     expected, mean, stddev,
-                    fabs(mean - expected), fabs(mean - expected) / stddev);
+                    fabs(mean - expected),
+                    fabs(mean - expected) / stddev,
+                    fabs(mean - expected) / line_time(kmode));

Thanks for this new approach, I have tested this patch on different machines
with different modes as below.

Mode: 1920x1080@60Hz Connectors: HDMI-A-2
Mode: 1920x1080@60Hz Connectors: DP-1
Mode: 1920x1080@60Hz Connectors: DP-2
Mode: 2560x1440@60Hz Connectors: eDP-1
Mode: 3840x2160@60Hz Connectors: DP-2

And all the testcase regarding kms_setmode seems to passing on 5.8.x and 5.10-0-rcx kernel.

Thanks
-Anand
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Re: [igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval

[Chris Wilson]

Quoting Ram Moon, AnandX (2020-11-20 09:12:40)
> Hi Chris,
> 
> -----Original Message-----
> From: Ram Moon, AnandX 
> Sent: Tuesday, November 3, 2020 11:28 PM
> To: Chris Wilson <chris@chris-wilson.co.uk>; igt-dev@lists.freedesktop.org
> Subject: RE: [igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval
> 
> Hi Chris,
> 
> Thanks for your review comment.
> 
> -----Original Message-----
> From: Chris Wilson <chris@chris-wilson.co.uk>
> Sent: Tuesday, November 3, 2020 4:19 PM
> To: Ram Moon, AnandX <anandx.ram.moon@intel.com>; igt-dev@lists.freedesktop.org
> Cc: Ram Moon, AnandX <anandx.ram.moon@intel.com>
> Subject: Re: [igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval
> 
> Quoting Anand Moon (2020-11-02 09:08:36)
> > Using confidence interval formula accuracy is estimates approximately 
> > at 95% when {X} is the average of a sample of size n.
> > Use this confidence interval formula as used in statistics to estimate 
> > the accuracy.
> > 
> > Signed-off-by: Anand Moon <anandx.ram.moon@intel.com>
> > ---
> > See below link.
> > https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule#Cumulati
> > ve_distribution_function
> > ---
> >  tests/kms_setmode.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/tests/kms_setmode.c b/tests/kms_setmode.c index
> > 92f3ead2..58814a13 100644
> > --- a/tests/kms_setmode.c
> > +++ b/tests/kms_setmode.c
> > @@ -494,7 +494,7 @@ static void check_timings(int crtc_idx, const drmModeModeInfo *kmode)
> >          * which depend on timing, giving the lowest acceptable MTBF of 5.6s
> >          * for 60Hz sampling rate.
> >          */
> > -       accuracy = 3. * stddev;
> > +       accuracy = 3. * stddev / sqrt(CALIBRATE_TS_STEPS);
> 
> Oops, yes, this should be standard error rather than deviation. Could you add igt_stats_get_std_error() so we don't hardcode N?
> -Chris
> 
> Do you want me to rename accuracy to std_error and use stats.n_values instead of CALIBRATE_TS_STEPS I could not find the definition of igt_stats_get_std_error function. 
> 
> -Anand
> 
> Thanks for fixing the code changes.
> 
> Actually above changes fix the issue to improve the accuracy calculations.
> But now I am able to reproduce the original bug using 4K monitors on 5.8.x kernel, See below logs.
> 
>     CRTC[98] [Pipe A] Mode: 3840x2160@60Hz Connectors: DP-2[330] Expected frametime: 16668us; measured 16672.3us +- 1.805us accuracy 0.00% [0.07 scanlines]
> (kms_setmode:14315) CRITICAL: Test assertion failure function check_timings, file ../tests/kms_setmode.c:544:
> (kms_setmode:14315) CRITICAL: Failed assertion: fabs(mean - expected) < 1.718 * stddev
> (kms_setmode:14315) CRITICAL: vblank interval differs from modeline! expected 16667.6us, measured 16672us +- 1.805us, difference 4.7us (2.6 sigma) Stack trace:
>   #0 ../lib/igt_core.c:1734 __igt_fail_assert()
>   #1 ../tests/kms_setmode.c:544 test_one_combination()
>   #2 ../tests/kms_setmode.c:834 __real_main883()
>   #3 ../tests/kms_setmode.c:883 main()
>   #4 ../csu/libc-start.c:342 __libc_start_main()
>   #5 [_start+0x2e]
> Subtest basic failed.
> **** DEBUG ****
>  
> So after in digging into the below comments it turns out that *confidence interval* with respect to standard deviation is calculated with *Cumulative distribution function* (formula)
> 
> As per the Wikipedia table
> For various values of z, the percentage of values expected to lie in and outside the symmetric interval, CI = (−zσ, zσ), are as follows:
> [0] https://en.wikipedia.org/wiki/Standard_deviation#Rules_for_normally_distributed_data
> 
> It turns out that  *3 σ* gives around proportion percentage 99.7300204% which is according to the CI = (−zσ, zσ) table.
> 
> I would like to submit a below patch as this changes fix the overall bug.
> Please share your thought and suggestion on any alternative approach I should try.

You would also have to update the comments as it no longer matches the
broaden 90% critical value.

Still debating what is a sensible error rate, but in the meantime I
would suggest a different approach: ignore the deviation if it is within
a single scanline.

Something like:

-       igt_assert_f(fabs(mean - expected) < 1.718 * stddev,
-                    "vblank interval differs from modeline! expected %.1fus, measured %1.fus +- %.3fus, difference %.1fus (%.1f sigma)\n",
+       igt_assert_f(fabs(mean - expected) < max(line_time(kmode), 1.718 * stddev),
+                    "vblank interval differs from modeline! expected %.1fus, measured %1.fus +- %.3fus, difference %.1fus (%.1f sigma, %.1f scanlines)\n",
                     expected, mean, stddev,
-                    fabs(mean - expected), fabs(mean - expected) / stddev);
+                    fabs(mean - expected),
+                    fabs(mean - expected) / stddev,
+                    fabs(mean - expected) / line_time(kmode));
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Re: [igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval

[Ram Moon, AnandX]

Hi Chris,

-----Original Message-----
From: Ram Moon, AnandX 
Sent: Tuesday, November 3, 2020 11:28 PM
To: Chris Wilson <chris@chris-wilson.co.uk>; igt-dev@lists.freedesktop.org
Subject: RE: [igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval

Hi Chris,

Thanks for your review comment.

-----Original Message-----
From: Chris Wilson <chris@chris-wilson.co.uk>
Sent: Tuesday, November 3, 2020 4:19 PM
To: Ram Moon, AnandX <anandx.ram.moon@intel.com>; igt-dev@lists.freedesktop.org
Cc: Ram Moon, AnandX <anandx.ram.moon@intel.com>
Subject: Re: [igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval

Quoting Anand Moon (2020-11-02 09:08:36)
> Using confidence interval formula accuracy is estimates approximately 
> at 95% when {X} is the average of a sample of size n.
> Use this confidence interval formula as used in statistics to estimate 
> the accuracy.
> 
> Signed-off-by: Anand Moon <anandx.ram.moon@intel.com>
> ---
> See below link.
> https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule#Cumulati
> ve_distribution_function
> ---
>  tests/kms_setmode.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tests/kms_setmode.c b/tests/kms_setmode.c index
> 92f3ead2..58814a13 100644
> --- a/tests/kms_setmode.c
> +++ b/tests/kms_setmode.c
> @@ -494,7 +494,7 @@ static void check_timings(int crtc_idx, const drmModeModeInfo *kmode)
>          * which depend on timing, giving the lowest acceptable MTBF of 5.6s
>          * for 60Hz sampling rate.
>          */
> -       accuracy = 3. * stddev;
> +       accuracy = 3. * stddev / sqrt(CALIBRATE_TS_STEPS);

Oops, yes, this should be standard error rather than deviation. Could you add igt_stats_get_std_error() so we don't hardcode N?
-Chris

Do you want me to rename accuracy to std_error and use stats.n_values instead of CALIBRATE_TS_STEPS I could not find the definition of igt_stats_get_std_error function. 

-Anand

Thanks for fixing the code changes.

Actually above changes fix the issue to improve the accuracy calculations.
But now I am able to reproduce the original bug using 4K monitors on 5.8.x kernel, See below logs.

    CRTC[98] [Pipe A] Mode: 3840x2160@60Hz Connectors: DP-2[330] Expected frametime: 16668us; measured 16672.3us +- 1.805us accuracy 0.00% [0.07 scanlines]
(kms_setmode:14315) CRITICAL: Test assertion failure function check_timings, file ../tests/kms_setmode.c:544:
(kms_setmode:14315) CRITICAL: Failed assertion: fabs(mean - expected) < 1.718 * stddev
(kms_setmode:14315) CRITICAL: vblank interval differs from modeline! expected 16667.6us, measured 16672us +- 1.805us, difference 4.7us (2.6 sigma) Stack trace:
  #0 ../lib/igt_core.c:1734 __igt_fail_assert()
  #1 ../tests/kms_setmode.c:544 test_one_combination()
  #2 ../tests/kms_setmode.c:834 __real_main883()
  #3 ../tests/kms_setmode.c:883 main()
  #4 ../csu/libc-start.c:342 __libc_start_main()
  #5 [_start+0x2e]
Subtest basic failed.
**** DEBUG ****
 
So after in digging into the below comments it turns out that *confidence interval* with respect to standard deviation is calculated with *Cumulative distribution function* (formula)

As per the Wikipedia table
For various values of z, the percentage of values expected to lie in and outside the symmetric interval, CI = (−zσ, zσ), are as follows:
[0] https://en.wikipedia.org/wiki/Standard_deviation#Rules_for_normally_distributed_data

It turns out that  *3 σ* gives around proportion percentage 99.7300204% which is according to the CI = (−zσ, zσ) table.

I would like to submit a below patch as this changes fix the overall bug.
Please share your thought and suggestion on any alternative approach I should try.

Thanks
Anand

naveen@naveen-GB-Z390-Garuda:~/anand/igt-gpu-tools.internal-rebasing$ git diff diff --git a/tests/kms_setmode.c b/tests/kms_setmode.c index 928a5a8cf..58da36985 100644
--- a/tests/kms_setmode.c
+++ b/tests/kms_setmode.c
@@ -526,7 +526,7 @@ static void check_timings(int crtc_idx, const drmModeModeInfo *kmode)
         * See:
         * https://en.wikipedia.org/wiki/Standard_deviation#Rules_for_normally_distributed_data
         */
-       igt_assert_f(fabs(mean - expected) < 1.718 * stddev,
+       igt_assert_f(fabs(mean - expected) < 3. * stddev,
                     "vblank interval differs from modeline! expected %.1fus, measured %1.fus +- %.3fus, difference %.1fus (%.1f sigma)\n",
                     expected, mean, stddev,
                     fabs(mean - expected), fabs(mean - expected) / stddev);

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Re: [igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval

[Ram Moon, AnandX]

Hi Chris,

Thanks for your review comment.

-----Original Message-----
From: Chris Wilson <chris@chris-wilson.co.uk> 
Sent: Tuesday, November 3, 2020 4:19 PM
To: Ram Moon, AnandX <anandx.ram.moon@intel.com>; igt-dev@lists.freedesktop.org
Cc: Ram Moon, AnandX <anandx.ram.moon@intel.com>
Subject: Re: [igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval

Quoting Anand Moon (2020-11-02 09:08:36)
> Using confidence interval formula accuracy is estimates approximately 
> at 95% when {X} is the average of a sample of size n.
> Use this confidence interval formula as used in statistics to estimate 
> the accuracy.
> 
> Signed-off-by: Anand Moon <anandx.ram.moon@intel.com>
> ---
> See below link.
> https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule#Cumulati
> ve_distribution_function
> ---
>  tests/kms_setmode.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tests/kms_setmode.c b/tests/kms_setmode.c index 
> 92f3ead2..58814a13 100644
> --- a/tests/kms_setmode.c
> +++ b/tests/kms_setmode.c
> @@ -494,7 +494,7 @@ static void check_timings(int crtc_idx, const drmModeModeInfo *kmode)
>          * which depend on timing, giving the lowest acceptable MTBF of 5.6s
>          * for 60Hz sampling rate.
>          */
> -       accuracy = 3. * stddev;
> +       accuracy = 3. * stddev / sqrt(CALIBRATE_TS_STEPS);

Oops, yes, this should be standard error rather than deviation. Could you add igt_stats_get_std_error() so we don't hardcode N?
-Chris

Do you want me to rename accuracy to std_error and use stats.n_values instead of CALIBRATE_TS_STEPS 
I could not find the definition of igt_stats_get_std_error function. 

-Anand


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Re: [igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval

[Chris Wilson]

Quoting Anand Moon (2020-11-02 09:08:36)
> Using confidence interval formula accuracy is estimates approximately
> at 95% when {X} is the average of a sample of size n.
> Use this confidence interval formula as used in statistics
> to estimate the accuracy.
> 
> Signed-off-by: Anand Moon <anandx.ram.moon@intel.com>
> ---
> See below link.
> https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule#Cumulative_distribution_function
> ---
>  tests/kms_setmode.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tests/kms_setmode.c b/tests/kms_setmode.c
> index 92f3ead2..58814a13 100644
> --- a/tests/kms_setmode.c
> +++ b/tests/kms_setmode.c
> @@ -494,7 +494,7 @@ static void check_timings(int crtc_idx, const drmModeModeInfo *kmode)
>          * which depend on timing, giving the lowest acceptable MTBF of 5.6s
>          * for 60Hz sampling rate.
>          */
> -       accuracy = 3. * stddev;
> +       accuracy = 3. * stddev / sqrt(CALIBRATE_TS_STEPS);

Oops, yes, this should be standard error rather than deviation. Could you
add igt_stats_get_std_error() so we don't hardcode N?
-Chris
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[igt-dev] [i-g-t] tests/kms_setmode: basic Improve accuracy with using of confidence interval

[Anand Moon]

Using confidence interval formula accuracy is estimates approximately
at 95% when {X} is the average of a sample of size n.
Use this confidence interval formula as used in statistics
to estimate the accuracy.

Signed-off-by: Anand Moon <anandx.ram.moon@intel.com>
---
See below link.
https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule#Cumulative_distribution_function
---
 tests/kms_setmode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/kms_setmode.c b/tests/kms_setmode.c
index 92f3ead2..58814a13 100644
--- a/tests/kms_setmode.c
+++ b/tests/kms_setmode.c
@@ -494,7 +494,7 @@ static void check_timings(int crtc_idx, const drmModeModeInfo *kmode)
 	 * which depend on timing, giving the lowest acceptable MTBF of 5.6s
 	 * for 60Hz sampling rate.
 	 */
-	accuracy = 3. * stddev;
+	accuracy = 3. * stddev / sqrt(CALIBRATE_TS_STEPS);
 
 	igt_info("Expected frametime: %.0fus; measured %.1fus +- %.3fus accuracy %.2f%% [%.2f scanlines]\n",
 		 expected, mean, stddev,
-- 
2.25.1

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