Re: [ANNOUNCE] 2.6.31-rc6-rt2

john stultz
2009-08-18T22:31:19Z

On Sun, Aug 16, 2009 at 1:41 PM, Thomas Gleixner<tglx@linutronix.de> wrote:
> We are pleased to announce the next update to our new preempt-rt
> series.
>
>    - update to 2.6.31-rc6
>

I'm seeing some bad scheduler behavior with this patch. I've seen
occasional bad behavior with 2.6.29-rt as well, but with .31-rt its
much worse.

I'm running a SCHED_OTHER cpubound benchmark (censored to
xxxxxxxxxxxxx in the logs) that runs for a number of minutes. With
2.6.31-rc6 I'm seeing really poor numbers and if I cat
/proc/sched_debug I see all of the cpu bound tasks are running on the
same cpu, while the other procs are basically idle. See the log below:

Any thoughts on how to debug this?

thanks
-john

Sched Debug Version: v0.09, 2.6.31-rc6-rt2 #2
now at 1293360.710541 msecs
.jiffies : 4295960656
.sysctl_sched_latency : 60.000000
.sysctl_sched_min_granularity : 12.000000
.sysctl_sched_wakeup_granularity : 15.000000
.sysctl_sched_child_runs_first : 0.000001
.sysctl_sched_features : 113917

cpu#0, 2193.531 MHz
.nr_running : 4
.load : 4096
.nr_switches : 4053338
.nr_load_updates : 1293349
.nr_uninterruptible : 43
.next_balance : 4295.960682
.curr->pid : 3515
.clock : 1293360.013589
.cpu_load[0] : 181618
.cpu_load[1] : 181618
.cpu_load[2] : 181618
.cpu_load[3] : 181618
.cpu_load[4] : 181618
.rt.rt_nr_running : 0
.rt.rt_nr_uninterruptible : -2
.rto_schedule : 1302873
.rto_schedule_tail : 0
.rto_wakeup : 0
.rto_pulled : 0
.rto_pushed : 0
.yld_count : 1
.sched_switch : 0
.sched_count : 8418031
.sched_goidle : 731106
.ttwu_count : 2747402
.ttwu_local : 2742052
.bkl_count : 543

cfs_rq[0]:
.exec_clock : 567085.631142
.MIN_vruntime : 852341.508897
.min_vruntime : 852341.017669
.max_vruntime : 852341.709960
.spread : 0.201063
.spread0 : 0.000000
.nr_running : 4
.load : 4096
.nr_spread_over : 0

rt_rq[0]:
.rt_nr_running : 0
.rt_throttled : 0
.rt_time : 0.887671
.rt_runtime : 950.000000

runnable tasks:
task PID tree-key switches prio
exec-runtime sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
xxxxxxxxxxxxx.g 3512 852341.508897 138832 120
852341.508897 135653.402650 434.695150
xxxxxxxxxxxxx.g 3513 852341.709960 138782 120
852341.709960 135605.356113 182.677943
xxxxxxxxxxxxx.g 3514 852341.654901 138935 120
852341.654901 135610.255788 237.499811
Rxxxxxxxxxxxxx.g 3515 852341.017669 138914 120
852341.017669 135610.205043 229.113644

cpu#1, 2193.531 MHz
.nr_running : 1
.load : 1024
.nr_switches : 2971216
.nr_load_updates : 1292739
.nr_uninterruptible : 3
.next_balance : 4295.960659
.curr->pid : 3555
.clock : 1293360.140904
.cpu_load[0] : 356068
.cpu_load[1] : 266796
.cpu_load[2] : 222179
.cpu_load[3] : 199897
.cpu_load[4] : 188742
.rt.rt_nr_running : 0
.rt.rt_nr_uninterruptible : -2
.rto_schedule : 1308223
.rto_schedule_tail : 0
.rto_wakeup : 0
.rto_pulled : 0
.rto_pushed : 0
.yld_count : 0
.sched_switch : 0
.sched_count : 2971729
.sched_goidle : 1288705
.ttwu_count : 1658086
.ttwu_local : 1650416
.bkl_count : 652

cfs_rq[1]:
.exec_clock : 13844.952496
.MIN_vruntime : 0.000001
.min_vruntime : 53350.708275
.max_vruntime : 0.000001
.spread : 0.000000
.spread0 : -798990.309394
.nr_running : 1
.load : 1024
.nr_spread_over : 6

rt_rq[1]:
.rt_nr_running : 0
.rt_throttled : 0
.rt_time : 0.521663
.rt_runtime : 950.000000

runnable tasks:
task PID tree-key switches prio
exec-runtime sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
R cat 3555 53321.260707 6 120
53321.260707 0.652065 10.616066

cpu#2, 2193.531 MHz
.nr_running : 0
.load : 0
.nr_switches : 2925158
.nr_load_updates : 1292419
.nr_uninterruptible : -23
.next_balance : 4295.960659
.curr->pid : 0
.clock : 1293360.258470
.cpu_load[0] : 177522
.cpu_load[1] : 177522
.cpu_load[2] : 177522
.cpu_load[3] : 177522
.cpu_load[4] : 177522
.rt.rt_nr_running : 0
.rt.rt_nr_uninterruptible : -2
.rto_schedule : 1295099
.rto_schedule_tail : 0
.rto_wakeup : 0
.rto_pulled : 0
.rto_pushed : 0
.yld_count : 0
.sched_switch : 0
.sched_count : 2925161
.sched_goidle : 1293820
.ttwu_count : 1630779
.ttwu_local : 1630221
.bkl_count : 0

cfs_rq[2]:
.exec_clock : 53.516855
.MIN_vruntime : 0.000001
.min_vruntime : 102.147228
.max_vruntime : 0.000001
.spread : 0.000000
.spread0 : -852238.870441
.nr_running : 0
.load : 0
.nr_spread_over : 0

rt_rq[2]:
.rt_nr_running : 0
.rt_throttled : 0
.rt_time : 0.374001
.rt_runtime : 950.000000

runnable tasks:
task PID tree-key switches prio
exec-runtime sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------

cpu#3, 2193.531 MHz
.nr_running : 0
.load : 0
.nr_switches : 2924897
.nr_load_updates : 1292090
.nr_uninterruptible : -23
.next_balance : 4295.960659
.curr->pid : 0
.clock : 1293360.383163
.cpu_load[0] : 177522
.cpu_load[1] : 177522
.cpu_load[2] : 177522
.cpu_load[3] : 177522
.cpu_load[4] : 177522
.rt.rt_nr_running : 0
.rt.rt_nr_uninterruptible : -2
.rto_schedule : 1294829
.rto_schedule_tail : 0
.rto_wakeup : 0
.rto_pulled : 0
.rto_pushed : 0
.yld_count : 0
.sched_switch : 0
.sched_count : 2924899
.sched_goidle : 1293542
.ttwu_count : 1630794
.ttwu_local : 1630705
.bkl_count : 0

cfs_rq[3]:
.exec_clock : 60.101923
.MIN_vruntime : 0.000001
.min_vruntime : 382.606699
.max_vruntime : 0.000001
.spread : 0.000000
.spread0 : -851958.410970
.nr_running : 0
.load : 0
.nr_spread_over : 0

rt_rq[3]:
.rt_nr_running : 0
.rt_throttled : 0
.rt_time : 0.365285
.rt_runtime : 950.000000

runnable tasks:
task PID tree-key switches prio
exec-runtime sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
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