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  1. @bobrik bobrik revised this gist Dec 8, 2017. 1 changed file with 8 additions and 1 deletion.
    9 changes: 8 additions & 1 deletion README.md
    View file
    Original file line number Diff line number Diff line change
    @@ -17,7 +17,14 @@ while on-CPU time should remain around 5ms.

    To make tests easier, we run code in a docker container. Code is in `cfs.go`.

    All tests were run on 4.14.4, but 4.9.51 has the same behavior.
    We tested:

    * Kernel 4.14.4, 4.9.51 and 4.4.88 on bare metal with NUMA
    * Xubuntu 17.04 with kernel 4.10.0-19-generic on VirtualBox
    * Ubuntu 16.04 with kernel 4.4.0-101-generic on DigitalOcean
    * Fedora 27 with kernel 4.13.9-300.fc27.x86_64 on DigitalOcean

    All with the same results.

    ### Running without throttling

  2. @bobrik bobrik created this gist Dec 8, 2017.
    482 changes: 482 additions & 0 deletions README.md
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,482 @@
    # Overly aggressive CFS

    We're looking at CPU bandwidth control via CFS:

    * https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt

    ## Reproduction program

    Program does number of iterations, in each iteration we burn CPU in small chunks
    until we get 5ms of real time spent. On each iteration we also print how much
    time we spent burning CPU, how much real time passed and how much CPU time.

    If we don't go over CFS quota, we should always get very close to 5ms.

    If we go over quota, it's fair to expect to have higher real timings,
    while on-CPU time should remain around 5ms.

    To make tests easier, we run code in a docker container. Code is in `cfs.go`.

    All tests were run on 4.14.4, but 4.9.51 has the same behavior.

    ### Running without throttling

    #### 100ms sleep between iterations

    As expected, nothing is throttled.

    ```
    $ docker run --rm -it -v $(pwd):$(pwd) -w $(pwd) golang:1.9.2 go run cfs.go -iterations 100 -sleep 100ms
    2017/12/08 01:39:54 [0] burn took 5ms, real time so far: 5ms, cpu time so far: 6ms
    2017/12/08 01:39:54 [1] burn took 5ms, real time so far: 110ms, cpu time so far: 11ms
    2017/12/08 01:39:55 [2] burn took 5ms, real time so far: 215ms, cpu time so far: 17ms
    2017/12/08 01:39:55 [3] burn took 5ms, real time so far: 320ms, cpu time so far: 23ms
    2017/12/08 01:39:55 [4] burn took 5ms, real time so far: 425ms, cpu time so far: 29ms
    2017/12/08 01:39:55 [5] burn took 5ms, real time so far: 530ms, cpu time so far: 35ms
    2017/12/08 01:39:55 [6] burn took 5ms, real time so far: 635ms, cpu time so far: 40ms
    2017/12/08 01:39:55 [7] burn took 5ms, real time so far: 741ms, cpu time so far: 46ms
    2017/12/08 01:39:55 [8] burn took 5ms, real time so far: 846ms, cpu time so far: 52ms
    2017/12/08 01:39:55 [9] burn took 5ms, real time so far: 951ms, cpu time so far: 57ms
    2017/12/08 01:39:55 [10] burn took 5ms, real time so far: 1056ms, cpu time so far: 63ms
    2017/12/08 01:39:55 [11] burn took 5ms, real time so far: 1161ms, cpu time so far: 68ms
    2017/12/08 01:39:56 [12] burn took 5ms, real time so far: 1266ms, cpu time so far: 75ms
    2017/12/08 01:39:56 [13] burn took 5ms, real time so far: 1371ms, cpu time so far: 80ms
    2017/12/08 01:39:56 [14] burn took 5ms, real time so far: 1476ms, cpu time so far: 86ms
    2017/12/08 01:39:56 [15] burn took 5ms, real time so far: 1582ms, cpu time so far: 92ms
    2017/12/08 01:39:56 [16] burn took 5ms, real time so far: 1687ms, cpu time so far: 98ms
    2017/12/08 01:39:56 [17] burn took 5ms, real time so far: 1792ms, cpu time so far: 104ms
    2017/12/08 01:39:56 [18] burn took 5ms, real time so far: 1897ms, cpu time so far: 109ms
    2017/12/08 01:39:56 [19] burn took 5ms, real time so far: 2002ms, cpu time so far: 116ms
    2017/12/08 01:39:56 [20] burn took 5ms, real time so far: 2107ms, cpu time so far: 121ms
    2017/12/08 01:39:57 [21] burn took 5ms, real time so far: 2212ms, cpu time so far: 127ms
    2017/12/08 01:39:57 [22] burn took 5ms, real time so far: 2317ms, cpu time so far: 134ms
    2017/12/08 01:39:57 [23] burn took 5ms, real time so far: 2423ms, cpu time so far: 139ms
    2017/12/08 01:39:57 [24] burn took 5ms, real time so far: 2528ms, cpu time so far: 145ms
    2017/12/08 01:39:57 [25] burn took 5ms, real time so far: 2633ms, cpu time so far: 150ms
    2017/12/08 01:39:57 [26] burn took 5ms, real time so far: 2738ms, cpu time so far: 157ms
    2017/12/08 01:39:57 [27] burn took 5ms, real time so far: 2843ms, cpu time so far: 162ms
    2017/12/08 01:39:57 [28] burn took 5ms, real time so far: 2948ms, cpu time so far: 169ms
    2017/12/08 01:39:57 [29] burn took 5ms, real time so far: 3053ms, cpu time so far: 175ms
    2017/12/08 01:39:57 [30] burn took 5ms, real time so far: 3158ms, cpu time so far: 180ms
    2017/12/08 01:39:58 [31] burn took 5ms, real time so far: 3264ms, cpu time so far: 187ms
    2017/12/08 01:39:58 [32] burn took 5ms, real time so far: 3369ms, cpu time so far: 192ms
    2017/12/08 01:39:58 [33] burn took 5ms, real time so far: 3474ms, cpu time so far: 198ms
    2017/12/08 01:39:58 [34] burn took 5ms, real time so far: 3579ms, cpu time so far: 203ms
    2017/12/08 01:39:58 [35] burn took 5ms, real time so far: 3684ms, cpu time so far: 210ms
    2017/12/08 01:39:58 [36] burn took 5ms, real time so far: 3789ms, cpu time so far: 215ms
    2017/12/08 01:39:58 [37] burn took 5ms, real time so far: 3894ms, cpu time so far: 221ms
    2017/12/08 01:39:58 [38] burn took 5ms, real time so far: 3999ms, cpu time so far: 227ms
    2017/12/08 01:39:58 [39] burn took 5ms, real time so far: 4104ms, cpu time so far: 233ms
    2017/12/08 01:39:59 [40] burn took 5ms, real time so far: 4209ms, cpu time so far: 239ms
    2017/12/08 01:39:59 [41] burn took 5ms, real time so far: 4315ms, cpu time so far: 244ms
    2017/12/08 01:39:59 [42] burn took 5ms, real time so far: 4420ms, cpu time so far: 250ms
    2017/12/08 01:39:59 [43] burn took 5ms, real time so far: 4525ms, cpu time so far: 255ms
    2017/12/08 01:39:59 [44] burn took 5ms, real time so far: 4630ms, cpu time so far: 262ms
    2017/12/08 01:39:59 [45] burn took 5ms, real time so far: 4735ms, cpu time so far: 268ms
    2017/12/08 01:39:59 [46] burn took 5ms, real time so far: 4840ms, cpu time so far: 273ms
    2017/12/08 01:39:59 [47] burn took 5ms, real time so far: 4945ms, cpu time so far: 279ms
    2017/12/08 01:39:59 [48] burn took 5ms, real time so far: 5050ms, cpu time so far: 285ms
    2017/12/08 01:39:59 [49] burn took 5ms, real time so far: 5155ms, cpu time so far: 291ms
    2017/12/08 01:40:00 [50] burn took 5ms, real time so far: 5261ms, cpu time so far: 296ms
    2017/12/08 01:40:00 [51] burn took 5ms, real time so far: 5366ms, cpu time so far: 302ms
    2017/12/08 01:40:00 [52] burn took 5ms, real time so far: 5471ms, cpu time so far: 307ms
    2017/12/08 01:40:00 [53] burn took 5ms, real time so far: 5576ms, cpu time so far: 314ms
    2017/12/08 01:40:00 [54] burn took 5ms, real time so far: 5681ms, cpu time so far: 320ms
    2017/12/08 01:40:00 [55] burn took 5ms, real time so far: 5786ms, cpu time so far: 325ms
    2017/12/08 01:40:00 [56] burn took 5ms, real time so far: 5891ms, cpu time so far: 332ms
    2017/12/08 01:40:00 [57] burn took 5ms, real time so far: 5996ms, cpu time so far: 337ms
    2017/12/08 01:40:00 [58] burn took 5ms, real time so far: 6101ms, cpu time so far: 343ms
    2017/12/08 01:40:01 [59] burn took 5ms, real time so far: 6207ms, cpu time so far: 349ms
    2017/12/08 01:40:01 [60] burn took 5ms, real time so far: 6312ms, cpu time so far: 355ms
    2017/12/08 01:40:01 [61] burn took 5ms, real time so far: 6417ms, cpu time so far: 361ms
    2017/12/08 01:40:01 [62] burn took 5ms, real time so far: 6522ms, cpu time so far: 366ms
    2017/12/08 01:40:01 [63] burn took 5ms, real time so far: 6627ms, cpu time so far: 372ms
    2017/12/08 01:40:01 [64] burn took 5ms, real time so far: 6732ms, cpu time so far: 377ms
    2017/12/08 01:40:01 [65] burn took 5ms, real time so far: 6837ms, cpu time so far: 384ms
    2017/12/08 01:40:01 [66] burn took 5ms, real time so far: 6942ms, cpu time so far: 389ms
    2017/12/08 01:40:01 [67] burn took 5ms, real time so far: 7048ms, cpu time so far: 396ms
    2017/12/08 01:40:01 [68] burn took 5ms, real time so far: 7153ms, cpu time so far: 401ms
    2017/12/08 01:40:02 [69] burn took 5ms, real time so far: 7258ms, cpu time so far: 408ms
    2017/12/08 01:40:02 [70] burn took 5ms, real time so far: 7363ms, cpu time so far: 414ms
    2017/12/08 01:40:02 [71] burn took 5ms, real time so far: 7468ms, cpu time so far: 419ms
    2017/12/08 01:40:02 [72] burn took 5ms, real time so far: 7573ms, cpu time so far: 426ms
    2017/12/08 01:40:02 [73] burn took 5ms, real time so far: 7678ms, cpu time so far: 431ms
    2017/12/08 01:40:02 [74] burn took 5ms, real time so far: 7783ms, cpu time so far: 437ms
    2017/12/08 01:40:02 [75] burn took 5ms, real time so far: 7889ms, cpu time so far: 442ms
    2017/12/08 01:40:02 [76] burn took 5ms, real time so far: 7994ms, cpu time so far: 449ms
    2017/12/08 01:40:02 [77] burn took 5ms, real time so far: 8099ms, cpu time so far: 455ms
    2017/12/08 01:40:03 [78] burn took 5ms, real time so far: 8204ms, cpu time so far: 460ms
    2017/12/08 01:40:03 [79] burn took 5ms, real time so far: 8309ms, cpu time so far: 466ms
    2017/12/08 01:40:03 [80] burn took 5ms, real time so far: 8414ms, cpu time so far: 471ms
    2017/12/08 01:40:03 [81] burn took 5ms, real time so far: 8519ms, cpu time so far: 478ms
    2017/12/08 01:40:03 [82] burn took 5ms, real time so far: 8624ms, cpu time so far: 483ms
    2017/12/08 01:40:03 [83] burn took 5ms, real time so far: 8730ms, cpu time so far: 489ms
    2017/12/08 01:40:03 [84] burn took 5ms, real time so far: 8835ms, cpu time so far: 495ms
    2017/12/08 01:40:03 [85] burn took 5ms, real time so far: 8940ms, cpu time so far: 501ms
    2017/12/08 01:40:03 [86] burn took 5ms, real time so far: 9045ms, cpu time so far: 507ms
    2017/12/08 01:40:03 [87] burn took 5ms, real time so far: 9150ms, cpu time so far: 512ms
    2017/12/08 01:40:04 [88] burn took 5ms, real time so far: 9255ms, cpu time so far: 518ms
    2017/12/08 01:40:04 [89] burn took 5ms, real time so far: 9360ms, cpu time so far: 523ms
    2017/12/08 01:40:04 [90] burn took 5ms, real time so far: 9465ms, cpu time so far: 529ms
    2017/12/08 01:40:04 [91] burn took 5ms, real time so far: 9570ms, cpu time so far: 535ms
    2017/12/08 01:40:04 [92] burn took 5ms, real time so far: 9675ms, cpu time so far: 541ms
    2017/12/08 01:40:04 [93] burn took 5ms, real time so far: 9781ms, cpu time so far: 547ms
    2017/12/08 01:40:04 [94] burn took 5ms, real time so far: 9886ms, cpu time so far: 552ms
    2017/12/08 01:40:04 [95] burn took 5ms, real time so far: 9991ms, cpu time so far: 559ms
    2017/12/08 01:40:04 [96] burn took 5ms, real time so far: 10096ms, cpu time so far: 564ms
    2017/12/08 01:40:05 [97] burn took 5ms, real time so far: 10201ms, cpu time so far: 570ms
    2017/12/08 01:40:05 [98] burn took 5ms, real time so far: 10306ms, cpu time so far: 575ms
    2017/12/08 01:40:05 [99] burn took 5ms, real time so far: 10411ms, cpu time so far: 582ms
    ```

    #### 1000ms sleep between iterations

    Same, no throttling here.

    ```
    $ docker run --rm -it -v $(pwd):$(pwd) -w $(pwd) golang:1.9.2 go run cfs.go -iterations 100 -sleep 1000ms
    2017/12/08 01:40:42 [0] burn took 5ms, real time so far: 5ms, cpu time so far: 6ms
    2017/12/08 01:40:43 [1] burn took 5ms, real time so far: 1010ms, cpu time so far: 12ms
    2017/12/08 01:40:44 [2] burn took 5ms, real time so far: 2015ms, cpu time so far: 18ms
    2017/12/08 01:40:45 [3] burn took 5ms, real time so far: 3020ms, cpu time so far: 24ms
    2017/12/08 01:40:46 [4] burn took 5ms, real time so far: 4026ms, cpu time so far: 30ms
    2017/12/08 01:40:47 [5] burn took 5ms, real time so far: 5031ms, cpu time so far: 36ms
    2017/12/08 01:40:48 [6] burn took 5ms, real time so far: 6036ms, cpu time so far: 41ms
    2017/12/08 01:40:49 [7] burn took 5ms, real time so far: 7041ms, cpu time so far: 47ms
    2017/12/08 01:40:50 [8] burn took 5ms, real time so far: 8046ms, cpu time so far: 53ms
    2017/12/08 01:40:51 [9] burn took 5ms, real time so far: 9052ms, cpu time so far: 59ms
    2017/12/08 01:40:52 [10] burn took 5ms, real time so far: 10057ms, cpu time so far: 65ms
    2017/12/08 01:40:53 [11] burn took 5ms, real time so far: 11062ms, cpu time so far: 71ms
    2017/12/08 01:40:54 [12] burn took 5ms, real time so far: 12067ms, cpu time so far: 78ms
    2017/12/08 01:40:55 [13] burn took 5ms, real time so far: 13072ms, cpu time so far: 83ms
    2017/12/08 01:40:56 [14] burn took 5ms, real time so far: 14077ms, cpu time so far: 90ms
    2017/12/08 01:40:57 [15] burn took 5ms, real time so far: 15083ms, cpu time so far: 95ms
    2017/12/08 01:40:58 [16] burn took 5ms, real time so far: 16088ms, cpu time so far: 101ms
    2017/12/08 01:40:59 [17] burn took 5ms, real time so far: 17093ms, cpu time so far: 107ms
    2017/12/08 01:41:00 [18] burn took 5ms, real time so far: 18098ms, cpu time so far: 113ms
    2017/12/08 01:41:01 [19] burn took 5ms, real time so far: 19103ms, cpu time so far: 119ms
    2017/12/08 01:41:02 [20] burn took 5ms, real time so far: 20108ms, cpu time so far: 125ms
    2017/12/08 01:41:03 [21] burn took 5ms, real time so far: 21113ms, cpu time so far: 130ms
    2017/12/08 01:41:04 [22] burn took 5ms, real time so far: 22119ms, cpu time so far: 137ms
    2017/12/08 01:41:05 [23] burn took 5ms, real time so far: 23124ms, cpu time so far: 143ms
    2017/12/08 01:41:06 [24] burn took 5ms, real time so far: 24129ms, cpu time so far: 149ms
    2017/12/08 01:41:07 [25] burn took 5ms, real time so far: 25134ms, cpu time so far: 156ms
    2017/12/08 01:41:08 [26] burn took 5ms, real time so far: 26139ms, cpu time so far: 161ms
    2017/12/08 01:41:09 [27] burn took 5ms, real time so far: 27144ms, cpu time so far: 167ms
    2017/12/08 01:41:10 [28] burn took 5ms, real time so far: 28150ms, cpu time so far: 172ms
    2017/12/08 01:41:11 [29] burn took 5ms, real time so far: 29155ms, cpu time so far: 179ms
    2017/12/08 01:41:12 [30] burn took 5ms, real time so far: 30160ms, cpu time so far: 184ms
    2017/12/08 01:41:13 [31] burn took 5ms, real time so far: 31165ms, cpu time so far: 191ms
    2017/12/08 01:41:14 [32] burn took 5ms, real time so far: 32170ms, cpu time so far: 197ms
    2017/12/08 01:41:15 [33] burn took 5ms, real time so far: 33175ms, cpu time so far: 203ms
    2017/12/08 01:41:16 [34] burn took 5ms, real time so far: 34181ms, cpu time so far: 209ms
    2017/12/08 01:41:17 [35] burn took 5ms, real time so far: 35186ms, cpu time so far: 214ms
    2017/12/08 01:41:18 [36] burn took 5ms, real time so far: 36191ms, cpu time so far: 221ms
    2017/12/08 01:41:19 [37] burn took 5ms, real time so far: 37196ms, cpu time so far: 226ms
    2017/12/08 01:41:20 [38] burn took 5ms, real time so far: 38201ms, cpu time so far: 233ms
    2017/12/08 01:41:21 [39] burn took 5ms, real time so far: 39206ms, cpu time so far: 238ms
    2017/12/08 01:41:22 [40] burn took 5ms, real time so far: 40212ms, cpu time so far: 244ms
    2017/12/08 01:41:23 [41] burn took 5ms, real time so far: 41217ms, cpu time so far: 251ms
    2017/12/08 01:41:24 [42] burn took 5ms, real time so far: 42222ms, cpu time so far: 256ms
    2017/12/08 01:41:25 [43] burn took 5ms, real time so far: 43227ms, cpu time so far: 263ms
    2017/12/08 01:41:26 [44] burn took 5ms, real time so far: 44232ms, cpu time so far: 268ms
    2017/12/08 01:41:27 [45] burn took 5ms, real time so far: 45237ms, cpu time so far: 274ms
    2017/12/08 01:41:28 [46] burn took 5ms, real time so far: 46242ms, cpu time so far: 281ms
    2017/12/08 01:41:29 [47] burn took 5ms, real time so far: 47248ms, cpu time so far: 286ms
    2017/12/08 01:41:30 [48] burn took 5ms, real time so far: 48253ms, cpu time so far: 293ms
    2017/12/08 01:41:31 [49] burn took 5ms, real time so far: 49258ms, cpu time so far: 298ms
    2017/12/08 01:41:32 [50] burn took 5ms, real time so far: 50263ms, cpu time so far: 305ms
    2017/12/08 01:41:33 [51] burn took 5ms, real time so far: 51268ms, cpu time so far: 310ms
    2017/12/08 01:41:34 [52] burn took 5ms, real time so far: 52274ms, cpu time so far: 317ms
    2017/12/08 01:41:35 [53] burn took 5ms, real time so far: 53279ms, cpu time so far: 324ms
    2017/12/08 01:41:36 [54] burn took 5ms, real time so far: 54284ms, cpu time so far: 329ms
    2017/12/08 01:41:37 [55] burn took 5ms, real time so far: 55289ms, cpu time so far: 336ms
    2017/12/08 01:41:38 [56] burn took 5ms, real time so far: 56294ms, cpu time so far: 341ms
    2017/12/08 01:41:39 [57] burn took 5ms, real time so far: 57299ms, cpu time so far: 347ms
    2017/12/08 01:41:40 [58] burn took 5ms, real time so far: 58304ms, cpu time so far: 353ms
    2017/12/08 01:41:41 [59] burn took 5ms, real time so far: 59310ms, cpu time so far: 359ms
    2017/12/08 01:41:42 [60] burn took 5ms, real time so far: 60315ms, cpu time so far: 365ms
    2017/12/08 01:41:43 [61] burn took 5ms, real time so far: 61320ms, cpu time so far: 371ms
    2017/12/08 01:41:44 [62] burn took 5ms, real time so far: 62325ms, cpu time so far: 377ms
    2017/12/08 01:41:45 [63] burn took 5ms, real time so far: 63330ms, cpu time so far: 382ms
    2017/12/08 01:41:46 [64] burn took 5ms, real time so far: 64335ms, cpu time so far: 389ms
    2017/12/08 01:41:47 [65] burn took 5ms, real time so far: 65341ms, cpu time so far: 394ms
    2017/12/08 01:41:48 [66] burn took 5ms, real time so far: 66346ms, cpu time so far: 401ms
    2017/12/08 01:41:49 [67] burn took 5ms, real time so far: 67351ms, cpu time so far: 408ms
    2017/12/08 01:41:50 [68] burn took 5ms, real time so far: 68356ms, cpu time so far: 413ms
    2017/12/08 01:41:51 [69] burn took 5ms, real time so far: 69361ms, cpu time so far: 420ms
    2017/12/08 01:41:52 [70] burn took 5ms, real time so far: 70366ms, cpu time so far: 425ms
    2017/12/08 01:41:53 [71] burn took 5ms, real time so far: 71371ms, cpu time so far: 432ms
    2017/12/08 01:41:54 [72] burn took 5ms, real time so far: 72377ms, cpu time so far: 438ms
    2017/12/08 01:41:55 [73] burn took 5ms, real time so far: 73382ms, cpu time so far: 444ms
    2017/12/08 01:41:56 [74] burn took 5ms, real time so far: 74387ms, cpu time so far: 450ms
    2017/12/08 01:41:57 [75] burn took 5ms, real time so far: 75392ms, cpu time so far: 456ms
    2017/12/08 01:41:58 [76] burn took 5ms, real time so far: 76397ms, cpu time so far: 462ms
    2017/12/08 01:41:59 [77] burn took 5ms, real time so far: 77403ms, cpu time so far: 467ms
    2017/12/08 01:42:00 [78] burn took 5ms, real time so far: 78408ms, cpu time so far: 474ms
    2017/12/08 01:42:01 [79] burn took 5ms, real time so far: 79413ms, cpu time so far: 479ms
    2017/12/08 01:42:02 [80] burn took 5ms, real time so far: 80418ms, cpu time so far: 486ms
    2017/12/08 01:42:03 [81] burn took 5ms, real time so far: 81423ms, cpu time so far: 492ms
    2017/12/08 01:42:04 [82] burn took 5ms, real time so far: 82428ms, cpu time so far: 498ms
    2017/12/08 01:42:05 [83] burn took 5ms, real time so far: 83434ms, cpu time so far: 505ms
    2017/12/08 01:42:06 [84] burn took 5ms, real time so far: 84439ms, cpu time so far: 510ms
    2017/12/08 01:42:07 [85] burn took 5ms, real time so far: 85444ms, cpu time so far: 516ms
    2017/12/08 01:42:08 [86] burn took 5ms, real time so far: 86449ms, cpu time so far: 522ms
    2017/12/08 01:42:09 [87] burn took 5ms, real time so far: 87454ms, cpu time so far: 528ms
    2017/12/08 01:42:10 [88] burn took 5ms, real time so far: 88460ms, cpu time so far: 535ms
    2017/12/08 01:42:11 [89] burn took 5ms, real time so far: 89465ms, cpu time so far: 540ms
    2017/12/08 01:42:12 [90] burn took 5ms, real time so far: 90470ms, cpu time so far: 547ms
    2017/12/08 01:42:13 [91] burn took 5ms, real time so far: 91475ms, cpu time so far: 552ms
    2017/12/08 01:42:14 [92] burn took 5ms, real time so far: 92480ms, cpu time so far: 559ms
    2017/12/08 01:42:15 [93] burn took 5ms, real time so far: 93485ms, cpu time so far: 564ms
    2017/12/08 01:42:16 [94] burn took 5ms, real time so far: 94490ms, cpu time so far: 570ms
    2017/12/08 01:42:17 [95] burn took 5ms, real time so far: 95496ms, cpu time so far: 576ms
    2017/12/08 01:42:18 [96] burn took 5ms, real time so far: 96501ms, cpu time so far: 582ms
    2017/12/08 01:42:19 [97] burn took 5ms, real time so far: 97506ms, cpu time so far: 588ms
    2017/12/08 01:42:20 [98] burn took 5ms, real time so far: 98511ms, cpu time so far: 594ms
    2017/12/08 01:42:21 [99] burn took 5ms, real time so far: 99516ms, cpu time so far: 600ms
    ```

    ## Running with throttling

    This is where things get interesting. We set cfs quota to 20ms and cfs period
    to 100ms, so we can use at most 20% of cpu during any 100ms period. If we ever
    go over 20ms of cpu time, we'll be throttled for the remaining of 100ms period.

    #### 100ms sleep between iterations

    We burn CPU for 5ms and then we sleep for 100ms, that sums up to 105ms,
    so in theory we should never go over quota. In practice, we see throttles
    from time to time.

    ```
    $ docker run --rm -it --cpu-quota 20000 --cpu-period 100000 -v $(pwd):$(pwd) -w $(pwd) golang:1.9.2 go run cfs.go -iterations 100 -sleep 100ms
    2017/12/08 01:42:50 [0] burn took 5ms, real time so far: 5ms, cpu time so far: 6ms
    2017/12/08 01:42:50 [1] burn took 5ms, real time so far: 194ms, cpu time so far: 12ms
    2017/12/08 01:42:50 [2] burn took 5ms, real time so far: 299ms, cpu time so far: 18ms
    2017/12/08 01:42:50 [3] burn took 5ms, real time so far: 404ms, cpu time so far: 23ms
    2017/12/08 01:42:51 [4] burn took 5ms, real time so far: 509ms, cpu time so far: 29ms
    2017/12/08 01:42:51 [5] burn took 5ms, real time so far: 614ms, cpu time so far: 35ms
    2017/12/08 01:42:51 [6] burn took 5ms, real time so far: 719ms, cpu time so far: 40ms
    2017/12/08 01:42:51 [7] burn took 5ms, real time so far: 824ms, cpu time so far: 46ms
    2017/12/08 01:42:51 [8] burn took 5ms, real time so far: 930ms, cpu time so far: 51ms
    2017/12/08 01:42:51 [9] burn took 5ms, real time so far: 1035ms, cpu time so far: 58ms
    2017/12/08 01:42:51 [10] burn took 5ms, real time so far: 1140ms, cpu time so far: 64ms
    2017/12/08 01:42:51 [11] burn took 5ms, real time so far: 1245ms, cpu time so far: 69ms
    2017/12/08 01:42:51 [12] burn took 5ms, real time so far: 1350ms, cpu time so far: 75ms
    2017/12/08 01:42:51 [13] burn took 5ms, real time so far: 1455ms, cpu time so far: 81ms
    2017/12/08 01:42:52 [14] burn took 5ms, real time so far: 1560ms, cpu time so far: 87ms
    2017/12/08 01:42:52 [15] burn took 5ms, real time so far: 1665ms, cpu time so far: 92ms
    2017/12/08 01:42:52 [16] burn took 5ms, real time so far: 1770ms, cpu time so far: 98ms
    2017/12/08 01:42:52 [17] burn took 5ms, real time so far: 1876ms, cpu time so far: 105ms
    2017/12/08 01:42:52 [18] burn took 5ms, real time so far: 1981ms, cpu time so far: 110ms
    2017/12/08 01:42:52 [19] burn took 5ms, real time so far: 2086ms, cpu time so far: 117ms
    2017/12/08 01:42:52 [20] burn took 5ms, real time so far: 2191ms, cpu time so far: 122ms
    2017/12/08 01:42:52 [21] burn took 97ms, real time so far: 2389ms, cpu time so far: 127ms
    2017/12/08 01:42:53 [22] burn took 5ms, real time so far: 2494ms, cpu time so far: 133ms
    2017/12/08 01:42:53 [23] burn took 5ms, real time so far: 2599ms, cpu time so far: 140ms
    2017/12/08 01:42:53 [24] burn took 5ms, real time so far: 2704ms, cpu time so far: 145ms
    2017/12/08 01:42:53 [25] burn took 5ms, real time so far: 2809ms, cpu time so far: 152ms
    2017/12/08 01:42:53 [26] burn took 5ms, real time so far: 2914ms, cpu time so far: 157ms
    2017/12/08 01:42:53 [27] burn took 5ms, real time so far: 3019ms, cpu time so far: 164ms
    2017/12/08 01:42:53 [28] burn took 5ms, real time so far: 3125ms, cpu time so far: 170ms
    2017/12/08 01:42:53 [29] burn took 5ms, real time so far: 3230ms, cpu time so far: 175ms
    2017/12/08 01:42:53 [30] burn took 5ms, real time so far: 3335ms, cpu time so far: 182ms
    2017/12/08 01:42:53 [31] burn took 5ms, real time so far: 3440ms, cpu time so far: 187ms
    2017/12/08 01:42:54 [32] burn took 5ms, real time so far: 3545ms, cpu time so far: 193ms
    2017/12/08 01:42:54 [33] burn took 5ms, real time so far: 3650ms, cpu time so far: 198ms
    2017/12/08 01:42:54 [34] burn took 5ms, real time so far: 3755ms, cpu time so far: 205ms
    2017/12/08 01:42:54 [35] burn took 5ms, real time so far: 3860ms, cpu time so far: 211ms
    2017/12/08 01:42:54 [36] burn took 5ms, real time so far: 3965ms, cpu time so far: 216ms
    2017/12/08 01:42:54 [37] burn took 5ms, real time so far: 4071ms, cpu time so far: 222ms
    2017/12/08 01:42:54 [38] burn took 5ms, real time so far: 4176ms, cpu time so far: 228ms
    2017/12/08 01:42:54 [39] burn took 5ms, real time so far: 4281ms, cpu time so far: 234ms
    2017/12/08 01:42:54 [40] burn took 5ms, real time so far: 4386ms, cpu time so far: 239ms
    2017/12/08 01:42:55 [41] burn took 5ms, real time so far: 4491ms, cpu time so far: 246ms
    2017/12/08 01:42:55 [42] burn took 97ms, real time so far: 4689ms, cpu time so far: 252ms
    2017/12/08 01:42:55 [43] burn took 5ms, real time so far: 4794ms, cpu time so far: 257ms
    2017/12/08 01:42:55 [44] burn took 5ms, real time so far: 4899ms, cpu time so far: 264ms
    2017/12/08 01:42:55 [45] burn took 5ms, real time so far: 5004ms, cpu time so far: 269ms
    2017/12/08 01:42:55 [46] burn took 5ms, real time so far: 5109ms, cpu time so far: 275ms
    2017/12/08 01:42:55 [47] burn took 5ms, real time so far: 5214ms, cpu time so far: 281ms
    2017/12/08 01:42:55 [48] burn took 5ms, real time so far: 5320ms, cpu time so far: 287ms
    2017/12/08 01:42:55 [49] burn took 5ms, real time so far: 5425ms, cpu time so far: 292ms
    2017/12/08 01:42:56 [50] burn took 5ms, real time so far: 5530ms, cpu time so far: 298ms
    2017/12/08 01:42:56 [51] burn took 5ms, real time so far: 5635ms, cpu time so far: 305ms
    2017/12/08 01:42:56 [52] burn took 5ms, real time so far: 5740ms, cpu time so far: 310ms
    2017/12/08 01:42:56 [53] burn took 5ms, real time so far: 5845ms, cpu time so far: 316ms
    2017/12/08 01:42:56 [54] burn took 5ms, real time so far: 5950ms, cpu time so far: 321ms
    2017/12/08 01:42:56 [55] burn took 5ms, real time so far: 6055ms, cpu time so far: 328ms
    2017/12/08 01:42:56 [56] burn took 5ms, real time so far: 6161ms, cpu time so far: 333ms
    2017/12/08 01:42:56 [57] burn took 5ms, real time so far: 6266ms, cpu time so far: 339ms
    2017/12/08 01:42:56 [58] burn took 5ms, real time so far: 6371ms, cpu time so far: 345ms
    2017/12/08 01:42:56 [59] burn took 5ms, real time so far: 6476ms, cpu time so far: 351ms
    2017/12/08 01:42:57 [60] burn took 5ms, real time so far: 6581ms, cpu time so far: 357ms
    2017/12/08 01:42:57 [61] burn took 5ms, real time so far: 6686ms, cpu time so far: 362ms
    2017/12/08 01:42:57 [62] burn took 5ms, real time so far: 6791ms, cpu time so far: 368ms
    2017/12/08 01:42:57 [63] burn took 5ms, real time so far: 6896ms, cpu time so far: 374ms
    2017/12/08 01:42:57 [64] burn took 5ms, real time so far: 7001ms, cpu time so far: 380ms
    2017/12/08 01:42:57 [65] burn took 5ms, real time so far: 7107ms, cpu time so far: 386ms
    2017/12/08 01:42:57 [66] burn took 5ms, real time so far: 7212ms, cpu time so far: 392ms
    2017/12/08 01:42:57 [67] burn took 5ms, real time so far: 7317ms, cpu time so far: 398ms
    2017/12/08 01:42:57 [68] burn took 5ms, real time so far: 7422ms, cpu time so far: 403ms
    2017/12/08 01:42:58 [69] burn took 5ms, real time so far: 7527ms, cpu time so far: 410ms
    2017/12/08 01:42:58 [70] burn took 5ms, real time so far: 7632ms, cpu time so far: 415ms
    2017/12/08 01:42:58 [71] burn took 5ms, real time so far: 7737ms, cpu time so far: 421ms
    2017/12/08 01:42:58 [72] burn took 5ms, real time so far: 7842ms, cpu time so far: 427ms
    2017/12/08 01:42:58 [73] burn took 5ms, real time so far: 7947ms, cpu time so far: 432ms
    2017/12/08 01:42:58 [74] burn took 5ms, real time so far: 8053ms, cpu time so far: 439ms
    2017/12/08 01:42:58 [75] burn took 5ms, real time so far: 8158ms, cpu time so far: 444ms
    2017/12/08 01:42:58 [76] burn took 5ms, real time so far: 8263ms, cpu time so far: 450ms
    2017/12/08 01:42:58 [77] burn took 5ms, real time so far: 8368ms, cpu time so far: 455ms
    2017/12/08 01:42:58 [78] burn took 5ms, real time so far: 8473ms, cpu time so far: 461ms
    2017/12/08 01:42:59 [79] burn took 5ms, real time so far: 8578ms, cpu time so far: 468ms
    2017/12/08 01:42:59 [80] burn took 5ms, real time so far: 8683ms, cpu time so far: 473ms
    2017/12/08 01:42:59 [81] burn took 5ms, real time so far: 8788ms, cpu time so far: 479ms
    2017/12/08 01:42:59 [82] burn took 5ms, real time so far: 8894ms, cpu time so far: 484ms
    2017/12/08 01:42:59 [83] burn took 5ms, real time so far: 9094ms, cpu time so far: 491ms
    2017/12/08 01:42:59 [84] burn took 5ms, real time so far: 9199ms, cpu time so far: 497ms
    2017/12/08 01:42:59 [85] burn took 5ms, real time so far: 9304ms, cpu time so far: 502ms
    2017/12/08 01:42:59 [86] burn took 5ms, real time so far: 9409ms, cpu time so far: 508ms
    2017/12/08 01:43:00 [87] burn took 5ms, real time so far: 9514ms, cpu time so far: 514ms
    2017/12/08 01:43:00 [88] burn took 5ms, real time so far: 9619ms, cpu time so far: 520ms
    2017/12/08 01:43:00 [89] burn took 5ms, real time so far: 9724ms, cpu time so far: 525ms
    2017/12/08 01:43:00 [90] burn took 5ms, real time so far: 9829ms, cpu time so far: 531ms
    2017/12/08 01:43:00 [91] burn took 5ms, real time so far: 9935ms, cpu time so far: 538ms
    2017/12/08 01:43:00 [92] burn took 5ms, real time so far: 10040ms, cpu time so far: 543ms
    2017/12/08 01:43:00 [93] burn took 5ms, real time so far: 10145ms, cpu time so far: 550ms
    2017/12/08 01:43:00 [94] burn took 5ms, real time so far: 10250ms, cpu time so far: 555ms
    2017/12/08 01:43:00 [95] burn took 5ms, real time so far: 10355ms, cpu time so far: 561ms
    2017/12/08 01:43:00 [96] burn took 5ms, real time so far: 10460ms, cpu time so far: 566ms
    2017/12/08 01:43:01 [97] burn took 5ms, real time so far: 10565ms, cpu time so far: 573ms
    2017/12/08 01:43:01 [98] burn took 5ms, real time so far: 10670ms, cpu time so far: 578ms
    2017/12/08 01:43:01 [99] burn took 5ms, real time so far: 10776ms, cpu time so far: 585ms
    ```

    #### 1000ms sleep between iterations

    With 5ms burns and 1000ms sleeps between them there are no 100ms intervals
    during which we can possibly see 20ms burned on CPU to get throttled. However,
    we see lots of throttling here. Almost every burn is throttled.

    ```
    $ docker run --rm -it --cpu-quota 20000 --cpu-period 100000 -v $(pwd):$(pwd) -w $(pwd) golang:1.9.2 go run cfs.go -iterations 100 -sleep 1000ms
    2017/12/08 01:44:27 [0] burn took 5ms, real time so far: 5ms, cpu time so far: 6ms
    2017/12/08 01:44:28 [1] burn took 100ms, real time so far: 1187ms, cpu time so far: 12ms
    2017/12/08 01:44:30 [2] burn took 5ms, real time so far: 2192ms, cpu time so far: 18ms
    2017/12/08 01:44:31 [3] burn took 99ms, real time so far: 3386ms, cpu time so far: 25ms
    2017/12/08 01:44:32 [4] burn took 5ms, real time so far: 4391ms, cpu time so far: 30ms
    2017/12/08 01:44:33 [5] burn took 100ms, real time so far: 5586ms, cpu time so far: 35ms
    2017/12/08 01:44:34 [6] burn took 99ms, real time so far: 6686ms, cpu time so far: 40ms
    2017/12/08 01:44:35 [7] burn took 5ms, real time so far: 7691ms, cpu time so far: 45ms
    2017/12/08 01:44:36 [8] burn took 99ms, real time so far: 8886ms, cpu time so far: 52ms
    2017/12/08 01:44:37 [9] burn took 99ms, real time so far: 9986ms, cpu time so far: 58ms
    2017/12/08 01:44:38 [10] burn took 5ms, real time so far: 10991ms, cpu time so far: 64ms
    2017/12/08 01:44:39 [11] burn took 99ms, real time so far: 12186ms, cpu time so far: 69ms
    2017/12/08 01:44:41 [12] burn took 5ms, real time so far: 13191ms, cpu time so far: 75ms
    2017/12/08 01:44:42 [13] burn took 99ms, real time so far: 14386ms, cpu time so far: 80ms
    2017/12/08 01:44:43 [14] burn took 99ms, real time so far: 15486ms, cpu time so far: 86ms
    2017/12/08 01:44:44 [15] burn took 100ms, real time so far: 16586ms, cpu time so far: 93ms
    2017/12/08 01:44:45 [16] burn took 5ms, real time so far: 17591ms, cpu time so far: 99ms
    2017/12/08 01:44:46 [17] burn took 99ms, real time so far: 18786ms, cpu time so far: 101ms
    2017/12/08 01:44:47 [18] burn took 99ms, real time so far: 19886ms, cpu time so far: 104ms
    2017/12/08 01:44:48 [19] burn took 5ms, real time so far: 20891ms, cpu time so far: 109ms
    2017/12/08 01:44:49 [20] burn took 100ms, real time so far: 22086ms, cpu time so far: 115ms
    2017/12/08 01:44:50 [21] burn took 99ms, real time so far: 23186ms, cpu time so far: 120ms
    2017/12/08 01:44:52 [22] burn took 99ms, real time so far: 24286ms, cpu time so far: 126ms
    2017/12/08 01:44:53 [23] burn took 5ms, real time so far: 25291ms, cpu time so far: 132ms
    2017/12/08 01:44:54 [24] burn took 99ms, real time so far: 26486ms, cpu time so far: 137ms
    2017/12/08 01:44:55 [25] burn took 5ms, real time so far: 27491ms, cpu time so far: 143ms
    2017/12/08 01:44:56 [26] burn took 99ms, real time so far: 28686ms, cpu time so far: 150ms
    2017/12/08 01:44:57 [27] burn took 5ms, real time so far: 29691ms, cpu time so far: 155ms
    2017/12/08 01:44:58 [28] burn took 100ms, real time so far: 30886ms, cpu time so far: 160ms
    2017/12/08 01:44:59 [29] burn took 5ms, real time so far: 31891ms, cpu time so far: 166ms
    2017/12/08 01:45:00 [30] burn took 99ms, real time so far: 33086ms, cpu time so far: 170ms
    2017/12/08 01:45:01 [31] burn took 99ms, real time so far: 34186ms, cpu time so far: 176ms
    2017/12/08 01:45:03 [32] burn took 99ms, real time so far: 35286ms, cpu time so far: 182ms
    2017/12/08 01:45:04 [33] burn took 5ms, real time so far: 36291ms, cpu time so far: 187ms
    2017/12/08 01:45:05 [34] burn took 99ms, real time so far: 37486ms, cpu time so far: 192ms
    2017/12/08 01:45:06 [35] burn took 99ms, real time so far: 38586ms, cpu time so far: 197ms
    2017/12/08 01:45:07 [36] burn took 99ms, real time so far: 39686ms, cpu time so far: 202ms
    2017/12/08 01:45:08 [37] burn took 5ms, real time so far: 40691ms, cpu time so far: 208ms
    2017/12/08 01:45:09 [38] burn took 99ms, real time so far: 41886ms, cpu time so far: 213ms
    2017/12/08 01:45:10 [39] burn took 99ms, real time so far: 42986ms, cpu time so far: 219ms
    2017/12/08 01:45:11 [40] burn took 99ms, real time so far: 44086ms, cpu time so far: 224ms
    2017/12/08 01:45:12 [41] burn took 99ms, real time so far: 45186ms, cpu time so far: 229ms
    2017/12/08 01:45:14 [42] burn took 99ms, real time so far: 46286ms, cpu time so far: 235ms
    2017/12/08 01:45:15 [43] burn took 99ms, real time so far: 47386ms, cpu time so far: 241ms
    2017/12/08 01:45:16 [44] burn took 100ms, real time so far: 48486ms, cpu time so far: 247ms
    2017/12/08 01:45:17 [45] burn took 99ms, real time so far: 49586ms, cpu time so far: 253ms
    2017/12/08 01:45:18 [46] burn took 99ms, real time so far: 50686ms, cpu time so far: 259ms
    2017/12/08 01:45:19 [47] burn took 5ms, real time so far: 51691ms, cpu time so far: 265ms
    2017/12/08 01:45:20 [48] burn took 99ms, real time so far: 52886ms, cpu time so far: 270ms
    2017/12/08 01:45:21 [49] burn took 5ms, real time so far: 53891ms, cpu time so far: 276ms
    2017/12/08 01:45:22 [50] burn took 99ms, real time so far: 55086ms, cpu time so far: 281ms
    2017/12/08 01:45:23 [51] burn took 99ms, real time so far: 56186ms, cpu time so far: 286ms
    2017/12/08 01:45:25 [52] burn took 99ms, real time so far: 57286ms, cpu time so far: 292ms
    2017/12/08 01:45:26 [53] burn took 5ms, real time so far: 58291ms, cpu time so far: 298ms
    2017/12/08 01:45:27 [54] burn took 99ms, real time so far: 59486ms, cpu time so far: 303ms
    2017/12/08 01:45:28 [55] burn took 5ms, real time so far: 60491ms, cpu time so far: 309ms
    2017/12/08 01:45:29 [56] burn took 99ms, real time so far: 61686ms, cpu time so far: 314ms
    2017/12/08 01:45:30 [57] burn took 5ms, real time so far: 62691ms, cpu time so far: 320ms
    2017/12/08 01:45:31 [58] burn took 100ms, real time so far: 63886ms, cpu time so far: 326ms
    2017/12/08 01:45:32 [59] burn took 99ms, real time so far: 64986ms, cpu time so far: 328ms
    2017/12/08 01:45:33 [60] burn took 5ms, real time so far: 65991ms, cpu time so far: 333ms
    2017/12/08 01:45:34 [61] burn took 99ms, real time so far: 67186ms, cpu time so far: 337ms
    2017/12/08 01:45:36 [62] burn took 5ms, real time so far: 68191ms, cpu time so far: 343ms
    2017/12/08 01:45:37 [63] burn took 100ms, real time so far: 69386ms, cpu time so far: 350ms
    2017/12/08 01:45:38 [64] burn took 99ms, real time so far: 70486ms, cpu time so far: 355ms
    2017/12/08 01:45:39 [65] burn took 100ms, real time so far: 71586ms, cpu time so far: 361ms
    2017/12/08 01:45:40 [66] burn took 5ms, real time so far: 72591ms, cpu time so far: 367ms
    2017/12/08 01:45:41 [67] burn took 5ms, real time so far: 73691ms, cpu time so far: 374ms
    2017/12/08 01:45:42 [68] burn took 94ms, real time so far: 74786ms, cpu time so far: 379ms
    2017/12/08 01:45:43 [69] burn took 99ms, real time so far: 75886ms, cpu time so far: 385ms
    2017/12/08 01:45:44 [70] burn took 5ms, real time so far: 76891ms, cpu time so far: 390ms
    2017/12/08 01:45:45 [71] burn took 99ms, real time so far: 78086ms, cpu time so far: 395ms
    2017/12/08 01:45:46 [72] burn took 99ms, real time so far: 79186ms, cpu time so far: 396ms
    2017/12/08 01:45:48 [73] burn took 5ms, real time so far: 80191ms, cpu time so far: 401ms
    2017/12/08 01:45:49 [74] burn took 99ms, real time so far: 81386ms, cpu time so far: 406ms
    2017/12/08 01:45:50 [75] burn took 5ms, real time so far: 82391ms, cpu time so far: 412ms
    2017/12/08 01:45:51 [76] burn took 99ms, real time so far: 83586ms, cpu time so far: 417ms
    2017/12/08 01:45:52 [77] burn took 5ms, real time so far: 84591ms, cpu time so far: 423ms
    2017/12/08 01:45:53 [78] burn took 99ms, real time so far: 85786ms, cpu time so far: 429ms
    2017/12/08 01:45:54 [79] burn took 5ms, real time so far: 86791ms, cpu time so far: 434ms
    2017/12/08 01:45:55 [80] burn took 100ms, real time so far: 87986ms, cpu time so far: 440ms
    2017/12/08 01:45:56 [81] burn took 99ms, real time so far: 89086ms, cpu time so far: 446ms
    2017/12/08 01:45:57 [82] burn took 99ms, real time so far: 90186ms, cpu time so far: 448ms
    2017/12/08 01:45:59 [83] burn took 99ms, real time so far: 91286ms, cpu time so far: 452ms
    2017/12/08 01:46:00 [84] burn took 99ms, real time so far: 92386ms, cpu time so far: 457ms
    2017/12/08 01:46:01 [85] burn took 99ms, real time so far: 93486ms, cpu time so far: 463ms
    2017/12/08 01:46:02 [86] burn took 5ms, real time so far: 94491ms, cpu time so far: 468ms
    2017/12/08 01:46:03 [87] burn took 99ms, real time so far: 95686ms, cpu time so far: 474ms
    2017/12/08 01:46:04 [88] burn took 5ms, real time so far: 96691ms, cpu time so far: 480ms
    2017/12/08 01:46:05 [89] burn took 99ms, real time so far: 97886ms, cpu time so far: 486ms
    2017/12/08 01:46:06 [90] burn took 5ms, real time so far: 98891ms, cpu time so far: 492ms
    2017/12/08 01:46:07 [91] burn took 100ms, real time so far: 100086ms, cpu time so far: 497ms
    2017/12/08 01:46:08 [92] burn took 5ms, real time so far: 101091ms, cpu time so far: 503ms
    2017/12/08 01:46:10 [93] burn took 99ms, real time so far: 102286ms, cpu time so far: 508ms
    2017/12/08 01:46:11 [94] burn took 5ms, real time so far: 103291ms, cpu time so far: 514ms
    2017/12/08 01:46:12 [95] burn took 99ms, real time so far: 104486ms, cpu time so far: 518ms
    2017/12/08 01:46:13 [96] burn took 99ms, real time so far: 105586ms, cpu time so far: 525ms
    2017/12/08 01:46:14 [97] burn took 99ms, real time so far: 106686ms, cpu time so far: 529ms
    2017/12/08 01:46:15 [98] burn took 99ms, real time so far: 107786ms, cpu time so far: 532ms
    2017/12/08 01:46:16 [99] burn took 5ms, real time so far: 108791ms, cpu time so far: 538ms
    ```

    ### 5000ms sleep between iterations

    Again, lots of unexpected throttling.

    ```
    $ docker run --rm -it --cpu-quota 20000 --cpu-period 100000 -v $(pwd):$(pwd) -w $(pwd) golang:1.9.2 go run cfs.go -iterations 10 -sleep 5000ms
    2017/12/08 01:46:45 [0] burn took 5ms, real time so far: 5ms, cpu time so far: 6ms
    2017/12/08 01:46:50 [1] burn took 100ms, real time so far: 5199ms, cpu time so far: 12ms
    2017/12/08 01:46:55 [2] burn took 98ms, real time so far: 10298ms, cpu time so far: 15ms
    2017/12/08 01:47:00 [3] burn took 5ms, real time so far: 15303ms, cpu time so far: 20ms
    2017/12/08 01:47:05 [4] burn took 99ms, real time so far: 20498ms, cpu time so far: 26ms
    2017/12/08 01:47:10 [5] burn took 99ms, real time so far: 25598ms, cpu time so far: 31ms
    2017/12/08 01:47:15 [6] burn took 99ms, real time so far: 30698ms, cpu time so far: 38ms
    2017/12/08 01:47:20 [7] burn took 99ms, real time so far: 35798ms, cpu time so far: 44ms
    2017/12/08 01:47:25 [8] burn took 99ms, real time so far: 40898ms, cpu time so far: 49ms
    2017/12/08 01:47:30 [9] burn took 99ms, real time so far: 45998ms, cpu time so far: 55ms
    ```
    53 changes: 53 additions & 0 deletions cfs.go
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,53 @@
    package main

    import (
    "crypto/sha512"
    "flag"
    "log"
    "syscall"
    "time"
    )

    func main() {
    sleep := flag.Duration("sleep", time.Second, "sleep between iterations")
    interations := flag.Int("iterations", 100, "number of iterations")
    flag.Parse()

    time.Sleep(time.Second)

    b := time.Now()

    for i := 0; i < *interations; i++ {
    s := time.Now()
    burn(time.Millisecond * 5)
    e := time.Now().Sub(s)

    log.Printf("[%d] burn took %dms, real time so far: %dms, cpu time so far: %dms", i, ms(e), ms(time.Since(b)), ms(usage()))

    time.Sleep(*sleep)
    }
    }

    func ms(duration time.Duration) int {
    return int(duration.Nanoseconds() / 1000 / 1000)
    }

    func burn(duration time.Duration) {
    s := time.Now()

    for {
    sum := sha512.New()
    sum.Write([]byte("banana"))
    sum.Sum([]byte{})

    if time.Since(s) > duration {
    break
    }
    }
    }

    func usage() time.Duration {
    r := syscall.Rusage{}
    syscall.Getrusage(syscall.RUSAGE_SELF, &r)
    return time.Duration(r.Stime.Nano() + r.Utime.Nano())
    }