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    SubjectRe: CFS Scheduler and real-time tasks
    On 5/17/07, Ingo Molnar <mingo@elte.hu> wrote:
    > hey, cool! Also try -v13 - it should be even more tighter.

    I tried -v13. However the scheduling "error" is now 10% (vs 2% with -v12).

    I also noticed strange behaviour with CPU hotplug. I offlined cpu1
    (echo 0 >/sys/devices/system/cpu/cpu1/online), and the typing speed on
    my terminal decreased noticably. I could hardly type something there.
    The system was otherwise idle (running in Xorg, and gnome-terminal).
    As soon as I started massive_intr.c workload, the keyboard typing
    speed became normal again. If I have a workload running, while I
    offline a CPU the keyboard is fine after cpu1 is offlined.
    Also the entire system froze once, when I offlined cpu1. I couldn't
    reproduce this.

    I don't know how -v12 behaved wrt to CPU hotplug.

    > > ./massiv_new 9 300
    > > 020860 00017782
    > > 020858 00017774
    > >
    > > RT JOB:020865 00003785
    > >
    > > 020859 00017048
    > > 020862 00017387
    > > 020855 00017494
    > > 020861 00017245
    > > 020863 00017492
    > > 020864 00017122

    Results with -v13:

    edwin@localhost ~ $ ./mo 9 300
    006203 00006071
    006198 00005712
    006201 00006088
    006196 00006208
    006200 00006166
    006195 00006306
    006199 00006403
    006197 00006288
    006202 00006237

    ./massiv_new 9 300
    013803 00010073
    013801 00009889
    013804 00010303
    013806 00009953
    013800 00010010
    013802 00010171
    013807 00009956
    013805 00010037

    RT JOB:013808 00002230

    Interesting, massiv_new has better precision than massiv_orig.

    Just in case it helps, here's me /proc/sched_debug (when system is
    idle, and later, when running the test):

    Sched Debug Version: v0.02
    now at 1187357967816 nsecs

    cpu: 0
    .nr_running : 0
    .raw_weighted_load : 0
    .nr_switches : 555712
    .nr_load_updates : 221754
    .nr_uninterruptible : 4294967190
    .jiffies : 221839
    .next_balance : 221835
    .curr->pid : 0
    .clock : 755701854416
    .prev_clock_raw : 871997978419
    .clock_warps : 0
    .clock_unstable_events : 97254
    .clock_max_delta : 4749235
    .fair_clock : 184031607224
    .prev_fair_clock : 0
    .exec_clock : 749010316890
    .prev_exec_clock : 0
    .wait_runtime : 59753136705
    .wait_runtime_overruns : 2689
    .wait_runtime_underruns: 1141
    .cpu_load[0] : 0
    .cpu_load[1] : 0
    .cpu_load[2] : 0
    .cpu_load[3] : 0
    .cpu_load[4] : 0
    .wait_runtime_rq_sum : 0

    runnable tasks:
    task PID tree-key delta waiting
    switches prio sum-exec sum-wait sum-sleep
    wait-overrun wait-underrun
    ------------------------------------------------------------------------------------------------------------------------------------------------------------------

    cpu: 1
    .nr_running : 1
    .raw_weighted_load : 1024
    .nr_switches : 378755
    .nr_load_updates : 202398
    .nr_uninterruptible : 106
    .jiffies : 221839
    .next_balance : 221830
    .curr->pid : 20421
    .clock : 794219468967
    .prev_clock_raw : 874002443396
    .clock_warps : 0
    .clock_unstable_events : 116368
    .clock_max_delta : 4531475
    .fair_clock : 175306014212
    .prev_fair_clock : 0
    .exec_clock : 718501418488
    .prev_exec_clock : 0
    .wait_runtime : -59753140134
    .wait_runtime_overruns : 1245
    .wait_runtime_underruns: 1604
    .cpu_load[0] : 0
    .cpu_load[1] : 0
    .cpu_load[2] : 0
    .cpu_load[3] : 0
    .cpu_load[4] : 0
    .wait_runtime_rq_sum : -34602

    runnable tasks:
    task PID tree-key delta waiting
    switches prio sum-exec sum-wait sum-sleep
    wait-overrun wait-underrun
    ------------------------------------------------------------------------------------------------------------------------------------------------------------------
    R cat 20421 175306048814 34602 -34602
    2 120 69205 -34602 853
    0 0


    And sched_debug output while running the test:

    Sched Debug Version: v0.02
    now at 1261993795754 nsecs

    cpu: 0
    .nr_running : 5
    .raw_weighted_load : 5120
    .nr_switches : 588021
    .nr_load_updates : 232164
    .nr_uninterruptible : 4294967190
    .jiffies : 240498
    .next_balance : 240508
    .curr->pid : 21096
    .clock : 770190363479
    .prev_clock_raw : 895084968848
    .clock_warps : 0
    .clock_unstable_events : 125214
    .clock_max_delta : 0
    .fair_clock : 190695995910
    .prev_fair_clock : 0
    .exec_clock : 763286081256
    .prev_exec_clock : 0
    .wait_runtime : 68703429598
    .wait_runtime_overruns : 2978
    .wait_runtime_underruns: 1273
    .cpu_load[0] : 5120
    .cpu_load[1] : 5119
    .cpu_load[2] : 5110
    .cpu_load[3] : 5077
    .cpu_load[4] : 5037
    .wait_runtime_rq_sum : -54771343

    runnable tasks:
    task PID tree-key delta waiting
    switches prio sum-exec sum-wait sum-sleep
    wait-overrun wait-underrun
    ------------------------------------------------------------------------------------------------------------------------------------------------------------------
    R mo 21096 190703231293 7235383 -7235383
    445 120 1813432308 -8250501 211806979
    0 1
    mo 21093 190704201003 8205093 -8472612
    450 120 1818737228 -12394371 206140729
    0 6
    mo 21094 190704732208 8736298 -9665761
    464 120 1816895620 -12925451 204333757
    0 4
    mo 21092 190704971831 8975921 -15574122
    456 120 1817099155 -16680247 208648471
    0 2
    mo 21091 190705631487 9635577 -13823465
    457 120 1816983212 -16160000 204693203
    0 4

    cpu: 1
    .nr_running : 5
    .raw_weighted_load : 5120
    .nr_switches : 415103
    .nr_load_updates : 211674
    .nr_uninterruptible : 106
    .jiffies : 240498
    .next_balance : 240516
    .curr->pid : 21291
    .clock : 806335506481
    .prev_clock_raw : 897090740058
    .clock_warps : 0
    .clock_unstable_events : 150133
    .clock_max_delta : 0
    .fair_clock : 179777580248
    .prev_fair_clock : 0
    .exec_clock : 730473748729
    .prev_exec_clock : 0
    .wait_runtime : -68769955037
    .wait_runtime_overruns : 1250
    .wait_runtime_underruns: 1885
    .cpu_load[0] : 4096
    .cpu_load[1] : 4293
    .cpu_load[2] : 5044
    .cpu_load[3] : 7236
    .cpu_load[4] : 8445
    .wait_runtime_rq_sum : -11785269

    runnable tasks:
    task PID tree-key delta waiting
    switches prio sum-exec sum-wait sum-sleep
    wait-overrun wait-underrun
    ------------------------------------------------------------------------------------------------------------------------------------------------------------------
    R cat 21291 179777631414 51166 -51166
    2 120 66773 -51166 53218
    0 0
    mo 21095 179778195659 615411 -799325
    737 120 2088825958 -799325 201402067
    0 0
    mo 21090 179778267640 687392 -711781
    760 120 2094378519 -711781 208607795
    0 0
    mo 21097 179781627293 4047045 -5262328
    789 120 2090034861 -5262328 202105919
    0 0
    mo 21089 179782321359 4741111 -4960669
    757 120 2094677840 -4960669 202830299
    0 0
    -
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