linux-kernel - 4.3 group scheduling regression

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Message-ID: <1444585321.4169.18.camel@gmail.com>
Date:	Sun, 11 Oct 2015 19:42:01 +0200
From:	Mike Galbraith <umgwanakikbuti@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org, Yuyang Du <yuyang.du@...el.com>
Subject: 4.3 group scheduling regression

(change subject, CCs)

On Sun, 2015-10-11 at 04:25 +0200, Mike Galbraith wrote:

> > Is the interactivity the same (horrible) at fe32d3cd5e8e (ie, before the
> > load tracking rewrite from Yuyang)?

It is the rewrite, 9d89c257dfb9c51a532d69397f6eed75e5168c35.

Watching 8 single hog groups vs 1 tbench group, master vs 4.2.3, I saw
no big hairy difference, just as 1 group of 8 hogs vs 8 groups of 1.

8 single hog groups vs the less hungry mplayer otoh is quite different

100 second scripted recordings:
(note: "testo" is kde konsole acting as task group launch vehicle)

master
 -----------------------------------------------------------------------------------------------------------------
  Task                  |   Runtime ms  | Switches | Average delay ms | Maximum delay ms | Maximum delay at       |
 -----------------------------------------------------------------------------------------------------------------
  oink:(8)              | 787637.964 ms |    16242 | avg:    0.557 ms | max:   68.993 ms | max at:    239.126118 s
  mplayer:(25)          |   5477.234 ms |     8504 | avg:   16.395 ms | max: 2100.233 ms | max at:    282.850734 s
  Xorg:997              |   1773.218 ms |     4680 | avg:    4.857 ms | max: 1640.194 ms | max at:    285.660210 s
  konsole:1789          |    649.323 ms |     1261 | avg:    6.747 ms | max:  156.282 ms | max at:    265.548523 s
  testo:(9)             |    454.046 ms |     2867 | avg:    5.961 ms | max:  276.371 ms | max at:    245.511282 s
  plasma-desktop:1753   |    223.251 ms |     1582 | avg:    4.220 ms | max:  299.354 ms | max at:    337.242542 s
  kwin:1745             |    156.746 ms |     2879 | avg:    2.398 ms | max:  355.765 ms | max at:    337.242490 s
  pulseaudio:1797       |     60.268 ms |     2573 | avg:    0.695 ms | max:   36.069 ms | max at:    292.318120 s
  threaded-ml:3477      |     47.076 ms |     3878 | avg:    7.083 ms | max: 1898.940 ms | max at:    254.919367 s
  perf:3437             |     28.525 ms |        4 | avg:  129.042 ms | max:  498.816 ms | max at:    336.102154 s

4.2.3
 -----------------------------------------------------------------------------------------------------------------
  Task                  |   Runtime ms  | Switches | Average delay ms | Maximum delay ms | Maximum delay at       |
 -----------------------------------------------------------------------------------------------------------------
  oink:(8)              | 741307.292 ms |    42325 | avg:    1.276 ms | max:   23.598 ms | max at:    192.459790 s
  mplayer:(25)          |  35296.804 ms |    35423 | avg:    1.715 ms | max:   71.972 ms | max at:    128.737783 s
  Xorg:929              |  13257.917 ms |    21583 | avg:    0.091 ms | max:   27.983 ms | max at:    102.272376 s
  testo:(9)             |   2315.080 ms |    13213 | avg:    0.133 ms | max:    6.632 ms | max at:    201.422570 s
  konsole:1747          |    938.939 ms |     1458 | avg:    0.096 ms | max:   15.006 ms | max at:    102.260294 s
  kwin:1703             |    815.384 ms |    17376 | avg:    0.464 ms | max:    9.311 ms | max at:    119.026179 s
  pulseaudio:1762       |    396.168 ms |    14338 | avg:    0.020 ms | max:    6.514 ms | max at:    115.928179 s
  threaded-ml:3477      |    310.132 ms |    23966 | avg:    0.428 ms | max:   27.974 ms | max at:    134.100588 s
  plasma-desktop:1711   |    239.232 ms |     1577 | avg:    0.048 ms | max:    7.072 ms | max at:    102.060279 s
  perf:3434             |     65.705 ms |        2 | avg:    0.054 ms | max:    0.105 ms | max at:    102.011221 s

master, mplayer solo reference
 -----------------------------------------------------------------------------------------------------------------
  Task                  |   Runtime ms  | Switches | Average delay ms | Maximum delay ms | Maximum delay at       |
 -----------------------------------------------------------------------------------------------------------------
  mplayer:(25)          |  32171.732 ms |    18416 | avg:    0.012 ms | max:    4.405 ms | max at:   4911.226038 s
  Xorg:948              |  14271.286 ms |    17396 | avg:    0.016 ms | max:    0.082 ms | max at:   4911.243020 s
  testo:4121            |   3594.784 ms |    11607 | avg:    0.015 ms | max:    0.078 ms | max at:   4981.705240 s
  kwin:1650             |   1209.387 ms |    17562 | avg:    0.012 ms | max:    1.612 ms | max at:   4911.245523 s
  konsole:1728          |    967.914 ms |     1498 | avg:    0.007 ms | max:    0.048 ms | max at:   4997.903759 s
  pulseaudio:1750       |    684.342 ms |    14460 | avg:    0.013 ms | max:    0.552 ms | max at:   4957.743502 s
  threaded-ml:4153      |    641.893 ms |    15748 | avg:    0.016 ms | max:    2.201 ms | max at:   4923.928810 s
  plasma-desktop:1658   |    150.068 ms |      569 | avg:    0.011 ms | max:    0.390 ms | max at:   4911.258650 s
  perf:4126             |     43.854 ms |        3 | avg:    0.022 ms | max:    0.051 ms | max at:   4959.327694 s

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