On Thu, 2007-09-20 at 06:55 +0200, Mike Galbraith wrote:
> On Wed, 2007-09-19 at 10:06 -0700, Tong Li wrote:
>
> > Were the experiments run on a 2-CPU system?
>
> Yes.
>
> > When Xorg experiences large
> > wait time, is it on the same CPU that has the two pinned tasks? If this is
> > the case, then the problem could be X somehow advanced faster and got a
> > larger vruntime then the two pinned tasks, so it had to wait for the
> > pinned ones to catch up before it got a chance to be scheduled.
>
> Good question. I've not yet been able to capture any event where
> vruntimes are that far apart in sched_debug.
But, I did just manage to trigger some horrid behavior, and log it. I
modified the kernel to print task's actual tree key instead of their
current vruntime, and was watching that while make -j2 was running (and
not seeing anything very interesting), when on a lark, I restarted
SuSE's system updater thingy. That beast chews 100% CPU for so long at
startup that I long ago got annoyed, and changed it to run at nice 19.
Anyway, when it started, interactivity went to hell in the proverbial
hand-basket, and the sched_debug log shows some interesting results..
like spread0 hitting -13659412644, and cc1 being keyed at -3867063305.
cpu#0, 2992.608 MHz
.nr_running : 4
.load : 4096
.nr_switches : 1105882
.nr_load_updates : 735146
.nr_uninterruptible : 4294966399
.jiffies : 1936201
.next_balance : 1936276
.curr->pid : 27004
.clock : 735034802877
.idle_clock : 0
.prev_clock_raw : 2259213083886
.clock_warps : 0
.clock_overflows : 677631
.clock_deep_idle_events : 0
.clock_max_delta : 999848
.cpu_load[0] : 4096
.cpu_load[1] : 3960
.cpu_load[2] : 3814
.cpu_load[3] : 3539
.cpu_load[4] : 3153
cfs_rq
.exec_clock : 623175870707
.MIN_vruntime : 3791173262297
.min_vruntime : 3791173259723
.max_vruntime : 3791173264579
.spread : 2282
.spread0 : 0
.nr_sync_min_vruntime : 296756
runnable tasks:
task PID tree-key switches prio exec-runtime sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
bash 6338 3212 554 120 3791173262935 104271360 645224098563
R cc1 27004 -7509103 6 120 3791165750620 15396029 13300466
make 27006 4856 6 120 3791173264579 9540879 6458208
make 27010 2574 3 120 3791173262297 8897680 0
cpu#1, 2992.608 MHz
.nr_running : 5
.load : 6208
.nr_switches : 1012995
.nr_load_updates : 747540
.nr_uninterruptible : 897
.jiffies : 1936201
.next_balance : 1936303
.curr->pid : 27012
.clock : 747426624818
.idle_clock : 0
.prev_clock_raw : 2259213140042
.clock_warps : 0
.clock_overflows : 582091
.clock_deep_idle_events : 0
.clock_max_delta : 999848
.cpu_load[0] : 6208
.cpu_load[1] : 4545
.cpu_load[2] : 3810
.cpu_load[3] : 3065
.cpu_load[4] : 2397
cfs_rq
.exec_clock : 581940255731
.MIN_vruntime : 3791835890838
.min_vruntime : 3791854778322
.max_vruntime : 3791902652145
.spread : 66761307
.spread0 : 681518599
.nr_sync_min_vruntime : 256743
runnable tasks:
task PID tree-key switches prio exec-runtime sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Xorg 5740 -18887484 157025 115 3791835890838 46597617 638567698716
update-status 26093 48184396 1537 139 3791902652145 5709334592 2622161813
sh 27011 -6808461 2 120 3791847969861 4162855 1457101
R cat 27012 -19965525 3 120 3791836175385 1756456 1974618
bash 27013 1498 2 120 3791854779820 394907 0
Sched Debug Version: v0.05-v20, 2.6.23-rc6-smp-d #43
now at 2237384024289 nsecs
cpu#0, 2992.608 MHz
.nr_running : 2
.load : 1039
.nr_switches : 1106019
.nr_load_updates : 736329
.nr_uninterruptible : 4294966399
.jiffies : 1937383
.next_balance : 1937428
.curr->pid : 27087
.clock : 736217427466
.idle_clock : 0
.prev_clock_raw : 2260395464994
.clock_warps : 0
.clock_overflows : 678147
.clock_deep_idle_events : 0
.clock_max_delta : 999848
.cpu_load[0] : 1039
.cpu_load[1] : 1039
.cpu_load[2] : 1039
.cpu_load[3] : 1039
.cpu_load[4] : 1039
cfs_rq
.exec_clock : 624358414291
.MIN_vruntime : 3806531640151
.min_vruntime : 3806501788119
.max_vruntime : 3806531640151
.spread : 0
.spread0 : 0
.nr_sync_min_vruntime : 296782
runnable tasks:
task PID tree-key switches prio exec-runtime sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
update-status 26093 56810274 1572 139 3806531640151 5929003154 2622161813
R cc1 27087 0 13 120 3806501788119 403581890 15024992
cpu#1, 2992.608 MHz
.nr_running : 2
.load : 2048
.nr_switches : 1013933
.nr_load_updates : 748722
.nr_uninterruptible : 898
.jiffies : 1937383
.next_balance : 1937455
.curr->pid : 27089
.clock : 748608445154
.idle_clock : 0
.prev_clock_raw : 2260394709751
.clock_warps : 0
.clock_overflows : 582583
.clock_deep_idle_events : 0
.clock_max_delta : 999848
.cpu_load[0] : 2048
.cpu_load[1] : 5016
.cpu_load[2] : 6366
.cpu_load[3] : 7081
.cpu_load[4] : 6895
cfs_rq
.exec_clock : 583122024084
.MIN_vruntime : 3806331397540
.min_vruntime : 3806350696772
.max_vruntime : 3806331397540
.spread : 0
.spread0 : -151091347
.nr_sync_min_vruntime : 256756
runnable tasks:
task PID tree-key switches prio exec-runtime sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
konsole 6330 -19299232 124476 120 3806331397540 17086991675 615801753460
R cat 27089 -19513636 2 120 3806331713718 1163204 7839421
Sched Debug Version: v0.05-v20, 2.6.23-rc6-smp-d #43
now at 2238396055118 nsecs
cpu#0, 2992.608 MHz
.nr_running : 4
.load : 3087
.nr_switches : 1106671
.nr_load_updates : 737341
.nr_uninterruptible : 4294966395
.jiffies : 1938395
.next_balance : 1938412
.curr->pid : 27115
.clock : 737229273643
.idle_clock : 0
.prev_clock_raw : 2261407091960
.clock_warps : 0
.clock_overflows : 678565
.clock_deep_idle_events : 0
.clock_max_delta : 999848
.cpu_load[0] : 3087
.cpu_load[1] : 3055
.cpu_load[2] : 2723
.cpu_load[3] : 2169
.cpu_load[4] : 1698
cfs_rq
.exec_clock : 625370185925
.MIN_vruntime : 3833041200497
.min_vruntime : 3833041199517
.max_vruntime : 3833103226422
.spread : 62025925
.spread0 : 0
.nr_sync_min_vruntime : 296798
runnable tasks:
task PID tree-key switches prio exec-runtime sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
bash 6334 980 4556 120 3833041200497 565634278 646894253582
update-status 26093 66364651 1667 139 3833103226422 6318237803 2622161813
cc1 27112 1387807 22 120 3833042327482 242204855 12705113
R cat 27115 -19905217 2 120 3833023008660 1844735 3670718
cpu#1, 2992.608 MHz
.nr_running : 2
.load : 4145
.nr_switches : 1014099
.nr_load_updates : 749734
.nr_uninterruptible : 901
.jiffies : 1938395
.next_balance : 1938479
.curr->pid : 27084
.clock : 749620291330
.idle_clock : 0
.prev_clock_raw : 2261406342542
.clock_warps : 0
.clock_overflows : 582991
.clock_deep_idle_events : 0
.clock_max_delta : 999848
.cpu_load[0] : 4145
.cpu_load[1] : 4145
.cpu_load[2] : 4136
.cpu_load[3] : 3934
.cpu_load[4] : 3342
cfs_rq
.exec_clock : 584133842523
.MIN_vruntime : 3819361786873
.min_vruntime : 3819381786873
.max_vruntime : 3819361786873
.spread : 0
.spread0 : -13659412644
.nr_sync_min_vruntime : 256768
runnable tasks:
task PID tree-key switches prio exec-runtime sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
kacpid 73 -20000000 1073 115 3819361786873 489384092 743825068255
R cc1 27084 -3867063305 138 120 3815518715812 1205052524 24535558
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- References:
- Re: [git] CFS-devel, group scheduler, fixes
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- Re: [git] CFS-devel, group scheduler, fixes
- Re: [git] CFS-devel, group scheduler, fixes
- Re: [git] CFS-devel, group scheduler, fixes
- Re: [git] CFS-devel, group scheduler, fixes
- Re: [git] CFS-devel, group scheduler, fixes
- Re: [git] CFS-devel, group scheduler, fixes
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