/srv/irclogs.ubuntu.com/2011/01/28/#ubuntu-kernel.txt

* virtuald wonders what systems hotplug cpus00:02
apwvirtuald, bigger ones :)00:17
virtualdno shit :p00:17
RAOFAnd laptop users who want to actually turn off a core.00:17
apwbut i think the hotplug also includes turning off cores to save .... what raof said00:18
virtuald:>00:18
elmoand people who want to be able to replace broken CPUs on the fly00:19
apwelmo, that one was a given :)00:20
virtualddon't we all want that :)00:22
=== bjf is now known as bjf[afk]
diwicapw, it seems linux has been updated to 2.6.38, but linux-meta is still at 2.6.37. Is this intentional?08:30
pscoe2hi08:54
pscoe2I am facing some problems with my ubuntu server08:54
pscoe2some processes..on closing dont die.. but rather they stay alice with futex_wait_queue_me in their stack08:55
pscoe2alive08:55
pscoe2anyone has any idea about futex_wait_queue_me?08:58
=== _LibertyZero is now known as LibertyZero
apwpscoe2, futexes are interprocess locks in userspace09:00
smbpscoe2, Not immediately. But its even unclear what release you are talking of09:01
apwpscoe2, what release you running, what processes are they, etc09:01
pscoe2i am running 10.0409:05
pscoe2LTS09:05
pscoe2and the process is apache09:05
pscoe2i can provide the stack if you need it09:05
apwi would suggest filing a bug against apache, and get the stack trace in there so people can see it09:06
pscoe2http://pastebin.com/T1qmS9Xv is the stack trace09:07
apwpscoe2, that simply looks like a normal interprocess wait ... from the stack trace09:08
apwfrom the info we have i am inclined to say its more likely a userspace problem than a kernel issue09:08
apwso i would file a bug on apache, unless you have some specific reason to say its a kernel issue09:08
apwpscoe2, is that the whole trace or is there more of that?09:10
pscoe2but this process has been in state from 1296205546 seconds09:10
pscoe2it is the data in the /proc/<pid>/stack file09:10
apwpscoe2, a futex is userspace locking support, so if the other end of the lock is not exiting either it won't complete09:11
pscoe2also i looked up on google about processes hanging on futex_wait_queue_me and found that there is a bug in ubuntu kernel which might lead to this09:11
apwpscoe2, do you have a pointer to this information 09:12
pscoe2http://www.uluga.ubuntuforums.org/showthread.php?t=151704309:13
pscoe2https://bugs.launchpad.net/ubuntu/+source/linux/+bug/48049709:13
ubot2Launchpad bug 480497 in linux "Various applications freeze on exit." [Undecided,Confirmed]09:13
apwpscoe2, nothing in the kernel bug 480497 actually shows any kernel issue.  the processes are stuck on a futex waiting but they can be killed ... which implies futex misshandling09:20
ubot2Launchpad bug 480497 in linux "Various applications freeze on exit." [Undecided,Confirmed] https://launchpad.net/bugs/48049709:20
apwwhich wouldn't be a kernel issue unless you cannot get rid of the process 09:21
pscoe2hmm..so if i can successfully do a kill -9 on the process it is not a kernel issue?09:21
apwpscoe2, if the process dies when killed then its likely the kernel is doing what is intended yes.  there may be a bug but its as likley a futex producer consumer issue in userspace 09:22
pscoe2hmm..09:22
apwthe kernel bug there is just a dog pile of issues with any app which might use pulseaudio ... so i am inclined to think its a bug with that for most of the games people09:22
apwpscoe2, without knowing how apache is trying to use its futexs it is hard to know whats happening09:23
pscoe2the issue i am facing has nothing to do with games though :)09:23
pscoe2ok09:23
pscoe2i do have another problem which i am facing on my personal laptop09:23
apwso i would normally recommend starting at the consumer of the futex and see if they can tell us what they wanted to happen as against what did happen09:23
pscoe2ok09:23
pscoe2from time to time a process kslowd used to pop up eating most of my cpu power09:24
pscoe2i read a lot about this problem only to find t has something to do with the mouse driver09:24
pscoe2i am running ubuntu 10.1009:25
apwyep i have seen that with grphics polling as well09:25
apwis it still happening?09:25
apwu t09:25
apwu09:25
pscoe2ya09:25
apwi think the ones we knew about have been fixed nw09:25
apwthen that needs a kernel bug filed09:26
pscoe2i upgraded my kernel to the newest version09:26
pscoe2now a different process kworker eats up the cpu09:26
pscoe2causing the same problem09:26
apwpscoe2, that is the same process in essence, just its name has changed09:26
pscoe2i am forced to use windows to keep my work going09:27
apwheh nice for you09:27
pscoe2i dont like windows though09:27
pscoe2so anything i can do momentarily to ease the discomfort09:27
pscoe2i do a renice on the process and decrease its priority09:28
pscoe2that eases it up for a bit but is not a solution09:28
apwwe need a bug filed on the exact version you are seeing it: filed with ubuntu-bug linux09:28
apwi am not sure those processes will respond well to being reniced09:28
pscoe2everything hangs anyways09:29
pscoe2i will file the bug..09:29
pscoe2Thanks09:29
apwpscoe2, there used to be kslowd debugging available, i don't know about kworker09:30
pscoe2hmm..09:30
pscoe2i guess i will boot in with the older kernel and try debugging kslowd09:30
diwicapw, it seems linux has been updated to 2.6.38, but linux-meta is still at 2.6.37. Is this intentional?09:31
apwdiwic, yes ... we have issues booting it on arm09:31
diwicapw, ok09:31
ohsixapw: #70912809:56
apwbug #70912809:56
ubot2Launchpad bug 709128 in linux "suspendand resumes only works once, freezes on second suspend" [Undecided,New] https://launchpad.net/bugs/70912809:56
ohsixhrm @ typo's and extra s's, must be tired10:09
=== yofel_ is now known as yofel
apw_cking: did he win yet ?12:56
kaushalhi12:56
kaushalI get CONFIG_TASK_DELAY_ACCT not enabled in kernel, cannot determine SWAPIN and IO % at the bottom while running iotop12:57
kaushalon 8.0412:57
kaushalPlease suggest/guide12:57
kaushalwhat does it mean12:57
apw_kaushal: 8.04 ... someone remind me which that is12:57
kaushalI see this host has high IO12:58
kaushalhigh IOwait12:58
smbapw_, Hardy12:58
apw_that option was not enabled in older kernels, as it was experimental and thought to cause performance regressions i believe12:58
kaushalis there a way to look for reason why there was high IO ?12:58
apw_smb: ahh, i doubt we are going to retroactivly enable anything back there for the general population12:58
* apw_ tried to remeber if blocktrace works on hardy12:59
* apw_ wished we at least called it 8.hardy.04 :)12:59
apw_smb: can you remember if blktrace is that old ?12:59
smbapw_, Not really wihtout more compelling reason and no I do not know either from the top of my head12:59
apw_kaushal: worth trying blktrace, that might give you the hints you want13:00
apw_(if it existed back in hardy days)13:00
kaushalok13:00
apw_otherwise you might be forced to build a kernel with that enabled, not sure13:00
kaushalok13:01
kaushalapw_: what does blktrace do13:01
kaushalis there a way to know why there was high IO ?13:01
kaushalAt the moment there is no IO13:02
apw_blktrace records the IO that is occuring, so you can review it to see where etc it is going, can help determine if it is swap etc13:02
apw_only of use when the problem is occuring of course13:02
kaushalso old history is lost ?13:03
kaushalI dont see anything in syslog,dmesg13:03
kaushalapw_: please suggest13:03
apw_kaushal: nope i don't know of any persistant information of that nature which is kept, it would be simply too big13:04
kaushalapw_: Thanks13:09
kaushalapw_: any example to use blktrace13:09
kaushalI mean some form of monitoring it 13:09
apw_kaushal: there muct be some examples in the man, but not something i've used extensivly13:10
ckingapw, no idea13:19
apwcking, he did in the end13:19
ckingrats, I missed that - got distracted13:19
=== diwic is now known as diwic_afk
=== sconklin-gone is now known as sconklin
=== bjf[afk] is now known as bjf
JFosconklin, when you get a moment, I am looking over the arsenal scripts now. What tags do you want me to omit from my processing? I've found the place to add them15:40
JFo:-)15:40
sconklinJFo: hold on while I collect those tags for you15:40
JFok, thanks15:41
sconklinJFo: anything with "kernel-tracking-bug" should not be spammed15:42
JFook15:42
bjfJFo, also anything tagged "kernel-release-tracker"15:44
JFok15:44
JFois it ever possible for one of the revert or reapply bugs to be brand new ever?15:45
JFowondering if they should be on there15:45
apwJFo, is this the 'test upstream version' script ?15:56
apwJFo, and did you get any joy from the launchpad dude ?15:56
JFostill haven't heard from him16:16
JFoyes, this is the one that asks for upstream testing16:16
JFoapw ^16:16
JFohmmmm, there is still a cking lurking about :-)16:18
apwJFo, we might want to modify waht it suggests for regression-*16:18
* JFo points apw at cking 16:18
JFoapw, it looks like it is supposed to be ignoring them16:18
ckinghey, I'm just flushing my buffers for the week16:19
JFoI am working to find out what it is actually doing16:19
JFocking, sure you are ;)16:19
* apw imagines cking on the crapper16:19
JFoheh16:19
ckingthat's not a pleasant visual image16:19
apwcking, you are not meant to be able to see it by now16:21
smosersmb, bug 708920, they've only seen it on the older lucid for sure.16:27
ubot2Launchpad bug 708920 in linux-ec2 "Strange 'fork/clone' blocking behavior under high cpu usage on EC2" [Undecided,New] https://launchpad.net/bugs/70892016:27
smoserbut apparently it has to run a while to see it.16:27
sforsheecnd, you know much about the ntrig synthesizers?16:28
smbsmoser, Yes, saw that somewhere in either mail or bug report. Still we should get confirmation about the newer image before spending time there and to find out we had been chasing a ghost.16:41
smoseryeah. i'd agree.16:41
smoserdo you have an instance up ?16:41
smosermaybe run some benchamrks, leave it up for a while.16:42
smosertry to recreate on your newer instance..16:42
smbsmoser, I got one running at the moment. Though without anything running. I'll get same "noise" started and see where it leads16:43
=== sconklin is now known as sconklin-lunch
* apw wa17:21
* apw wanders off to see a panto17:21
* tgardner wonders what is a panto ?17:23
elmotgardner: a show in a theatre that tends to involve lots of  audience interaction and is often aimed primarily at kids17:24
smbpantomimes playing17:24
tgardnerelmo, that explains why apw is so jazzed :)17:24
JFo<- lunch17:36
=== sforshee is now known as sforshee-lunch
=== sconklin-lunch is now known as sconklin
* tgardner --> lunch19:08
=== sforshee-lunch is now known as sforshee
* jjohansen -> lunch20:19
JFoenjoy20:19
JFo:)20:19
sforsheeJFo, question about bug statuses when they affect upstream linux20:24
sforsheedo we set the status to fix released when the fix is in an rc kernel, or do we wait for the final release?20:25
JFowe wait until it is in our kernel20:26
sforsheefor the "Linux (Ubuntu)" package, yes20:26
JFofor upstreams we have a bugwatch that automatically does the upstream status change20:26
JFomaybe I am misunderstanding20:27
JFowant to chat via mumble?20:27
sforsheemaybe a more concrete example would help20:27
sforsheeyeah, that sounds good20:27
JFo:)20:27
=== Quintasan_ is now known as Quintasan
* vanhoof waves bye23:12
=== vanhoof is now known as vanhoof[weekend]

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