Trusty hange -- how to find out why?

[joneall]

Every now and then, maybe after 5 minutes or maybe after 3 hours, the system hangs completely. The keyboard and mouse are ignored. All I can do is push the button.

How do I find out why? I do not see anything in syslog since the last boot info.

This is particularly annoying as my grub screen is useless, as explained at

Grub does not allow choice (https://www.kubuntuforums.net/showth...t-allow-choice)

so I can neither use the 14.04 system nor get to my older 13.04 one.

(How do I make a link in the forum so that the article title shows rather than the URL?)

[Snowhog]

To create a hyperlink you first type what you want others to see:

This is my hyperlink

Then, select the text and click on the hyperlink icon and type or post the URL you want to use.

[joneall]

It's just that I do not see any icon like that.

Also, how do I start analyzing my hangs, which still occur very randomly with a newly installed system?

[joneall]

It's just that I do not see any icon like that.

Could it be because at the bottom of the screen in the Posting Permissions it says "HTML code is off"? If so, how to get it "on"?

[joneall]

Still hanging...

Anyway, back to the main issue, the hang.

I have croned a small script to print out the result of

top -b -n 1 | head -15

every five minutes, but do not notice anything regular in there.

I started up the System Activity window and left it visible on all desktops. At the last hang, which occurred spontaneously while I was taking a nap (essential for us older retirees), the plasma-desktop line was selected, tho it was not at the top of the list.

I can find nothing interesting in the logs, but since I do not know what I am looking for, it is like the proverbial haystack.

I installed another system, Debian wheezy, on another partition and it seems to stand up longer, tho I am not sure of that. It eventually hangs too, which suggests a hardware problem.

I ran Memtest86+, but it tests only 3GB of memory: first 0-2GB, then 2-3GB. Never touches 3-4GB. Why is that? I have 4GB installed.

So opened 50 or so photos with Gimp and managed to push the memory usage up to 3.9 GB (according to the top command) or 80% of 4GB (according to the monitor widget). No problem.

Any suggestions would be appreciated.

[Teunis]

Having two independent installations show the same behaviour is indeed pointing to a harware problem, locking up is usually a RAM issue.
If concerned about the memory you might have to run the memtest for quite long, like at least overnight or even better some 24 hrs.
Opening the box up and reseating the various plugs and RAM is also a good and cheap possibility.
And check the fan for being clean, maybe run a temperature log on the various bits like CPU, GPU and HD.

Is this a 32- or 64-bit system?
As 32-bit will not adress much over 3GB of RAM.

[jlittle]

Is this a 32- or 64-bit system?
As 32-bit will not adress much over 3GB of RAM.

I thought that wasn't true with PAE kernels, as are all Ubuntu ones now?

Regards, John Little

[Teunis]

I'm not sure about the PAE stuff, haven't used 32-bit in a while.
But yeah, you are right!

Depending on the hardware you might have to enable it:
https://help.ubuntu.com/community/EnablingPAE

[joneall]

Yes, maybe a memory problem

Is this a 32- or 64-bit system?

64 bit.

Thanks for your suggestions. Will run memtest for a longer period.

I left it running for the night with Lxde and it hung only between 22:45 and 22:50 (between 2 crons). What I saw was interesting -- a gradual increase in the memory used from 1811864 at 15:15, to 3765740 just before the crash. Could point to a high-end memory problem.

$ grep buffers top-batch-1404-15to22.out
KiB Mem: 4046992 total, 1811864 used, 2235128 free, 137536 buffers
KiB Mem: 4046992 total, 2342028 used, 1704964 free, 141164 buffers
KiB Mem: 4046992 total, 2471460 used, 1575532 free, 142036 buffers
KiB Mem: 4046992 total, 2553060 used, 1493932 free, 142036 buffers
KiB Mem: 4046992 total, 2556108 used, 1490884 free, 142036 buffers
KiB Mem: 4046992 total, 2569284 used, 1477708 free, 142036 buffers
KiB Mem: 4046992 total, 2543888 used, 1503104 free, 142036 buffers
KiB Mem: 4046992 total, 2539332 used, 1507660 free, 142036 buffers
KiB Mem: 4046992 total, 2567936 used, 1479056 free, 142036 buffers
KiB Mem: 4046992 total, 2516960 used, 1530032 free, 142036 buffers
KiB Mem: 4046992 total, 2564872 used, 1482120 free, 142036 buffers
KiB Mem: 4046992 total, 2565252 used, 1481740 free, 142036 buffers
KiB Mem: 4046992 total, 2568788 used, 1478204 free, 142036 buffers
KiB Mem: 4046992 total, 2550532 used, 1496460 free, 142036 buffers
KiB Mem: 4046992 total, 2568944 used, 1478048 free, 142040 buffers
KiB Mem: 4046992 total, 2523792 used, 1523200 free, 142040 buffers
KiB Mem: 4046992 total, 2553236 used, 1493756 free, 142040 buffers
KiB Mem: 4046992 total, 2580232 used, 1466760 free, 142040 buffers
KiB Mem: 4046992 total, 2555440 used, 1491552 free, 142040 buffers
KiB Mem: 4046992 total, 2565824 used, 1481168 free, 142040 buffers
KiB Mem: 4046992 total, 2572724 used, 1474268 free, 142040 buffers
KiB Mem: 4046992 total, 2576468 used, 1470524 free, 142040 buffers
KiB Mem: 4046992 total, 2588628 used, 1458364 free, 142040 buffers
KiB Mem: 4046992 total, 2547704 used, 1499288 free, 142040 buffers
KiB Mem: 4046992 total, 2581592 used, 1465400 free, 142040 buffers
KiB Mem: 4046992 total, 2573460 used, 1473532 free, 142040 buffers
KiB Mem: 4046992 total, 2548656 used, 1498336 free, 142040 buffers
KiB Mem: 4046992 total, 2553344 used, 1493648 free, 142040 buffers
KiB Mem: 4046992 total, 2595720 used, 1451272 free, 142040 buffers
KiB Mem: 4046992 total, 2540608 used, 1506384 free, 142044 buffers
KiB Mem: 4046992 total, 2586880 used, 1460112 free, 142044 buffers
KiB Mem: 4046992 total, 2568484 used, 1478508 free, 142060 buffers
KiB Mem: 4046992 total, 2575552 used, 1471440 free, 142060 buffers
KiB Mem: 4046992 total, 2591376 used, 1455616 free, 142060 buffers
KiB Mem: 4046992 total, 2593496 used, 1453496 free, 142060 buffers
KiB Mem: 4046992 total, 2584576 used, 1462416 free, 142068 buffers
KiB Mem: 4046992 total, 2598284 used, 1448708 free, 142848 buffers
KiB Mem: 4046992 total, 2666656 used, 1380336 free, 144628 buffers
KiB Mem: 4046992 total, 2661512 used, 1385480 free, 146132 buffers
KiB Mem: 4046992 total, 2906808 used, 1140184 free, 147016 buffers
KiB Mem: 4046992 total, 3045288 used, 1001704 free, 148560 buffers
KiB Mem: 4046992 total, 2981240 used, 1065752 free, 150204 buffers
KiB Mem: 4046992 total, 3123376 used, 923616 free, 150840 buffers
KiB Mem: 4046992 total, 3185528 used, 861464 free, 151032 buffers
KiB Mem: 4046992 total, 3201908 used, 845084 free, 151176 buffers
KiB Mem: 4046992 total, 3191080 used, 855912 free, 151352 buffers
KiB Mem: 4046992 total, 3164316 used, 882676 free, 151536 buffers
KiB Mem: 4046992 total, 3185432 used, 861560 free, 151652 buffers
KiB Mem: 4046992 total, 3183452 used, 863540 free, 151868 buffers
KiB Mem: 4046992 total, 3493244 used, 553748 free, 148164 buffers
KiB Mem: 4046992 total, 3633264 used, 413728 free, 149472 buffers
KiB Mem: 4046992 total, 3595816 used, 451176 free, 206844 buffers
KiB Mem: 4046992 total, 3655708 used, 391284 free, 207284 buffers
KiB Mem: 4046992 total, 3690436 used, 356556 free, 207420 buffers
KiB Mem: 4046992 total, 3714816 used, 332176 free, 207552 buffers
KiB Mem: 4046992 total, 3718584 used, 328408 free, 207756 buffers
KiB Mem: 4046992 total, 3742680 used, 304312 free, 207856 buffers
KiB Mem: 4046992 total, 3724516 used, 322476 free, 207992 buffers
KiB Mem: 4046992 total, 3754672 used, 292320 free, 208100 buffers
KiB Mem: 4046992 total, 3763272 used, 283720 free, 208188 buffers
KiB Mem: 4046992 total, 3782796 used, 264196 free, 208272 buffers
KiB Mem: 4046992 total, 3729932 used, 317060 free, 208424 buffers
KiB Mem: 4046992 total, 3790348 used, 256644 free, 208508 buffers
KiB Mem: 4046992 total, 3799524 used, 247468 free, 208588 buffers
KiB Mem: 4046992 total, 3814804 used, 232188 free, 208656 buffers
KiB Mem: 4046992 total, 3786628 used, 260364 free, 208752 buffers
KiB Mem: 4046992 total, 3744168 used, 302824 free, 208816 buffers
KiB Mem: 4046992 total, 3755972 used, 291020 free, 208892 buffers
KiB Mem: 4046992 total, 3754824 used, 292168 free, 208952 buffers
KiB Mem: 4046992 total, 3771628 used, 275364 free, 209020 buffers
KiB Mem: 4046992 total, 3778068 used, 268924 free, 209072 buffers
KiB Mem: 4046992 total, 3786508 used, 260484 free, 209140 buffers
KiB Mem: 4046992 total, 3741556 used, 305436 free, 209212 buffers
KiB Mem: 4046992 total, 3745652 used, 301340 free, 209324 buffers
KiB Mem: 4046992 total, 3801360 used, 245632 free, 209404 buffers
KiB Mem: 4046992 total, 3766892 used, 280100 free, 209508 buffers
KiB Mem: 4046992 total, 3770496 used, 276496 free, 209592 buffers
KiB Mem: 4046992 total, 3786548 used, 260444 free, 209724 buffers
KiB Mem: 4046992 total, 3754444 used, 292548 free, 209820 buffers
KiB Mem: 4046992 total, 3768508 used, 278484 free, 210008 buffers
KiB Mem: 4046992 total, 3783048 used, 263944 free, 210140 buffers
KiB Mem: 4046992 total, 3790976 used, 256016 free, 210272 buffers
KiB Mem: 4046992 total, 3790020 used, 256972 free, 210340 buffers
KiB Mem: 4046992 total, 3739244 used, 307748 free, 210384 buffers
KiB Mem: 4046992 total, 3787372 used, 259620 free, 210464 buffers
KiB Mem: 4046992 total, 3791604 used, 255388 free, 210604 buffers
KiB Mem: 4046992 total, 3810956 used, 236036 free, 210700 buffers
KiB Mem: 4046992 total, 3823348 used, 223644 free, 210820 buffers
KiB Mem: 4046992 total, 3780700 used, 266292 free, 210880 buffers
KiB Mem: 4046992 total, 3751332 used, 295660 free, 210964 buffers
KiB Mem: 4046992 total, 3765740 used, 281252 free, 211028 buffers

[GreyGeek]

Some possibilities:
Temperature problem; Install a temperature widget in the panel at the bottom of the screen and watch it. I had a similar hang problem (with the occasional crash) that forced a reboot. The only events shown in the logs was the "shut down" and reboot. That widget allowed me to see the temp on the CPU rise. The max allowed for my i73610QM CPU is 105C. I started noticing problems around 90C. At 95C momentary video (Intel HD4000) hangs would occur. At 100C the mouse and keyboard response was jumpy. I never saw it get to 105C. Sometime after 95C was reached everything would freeze or the computer would spontaneously reboot. I got a can of air and blew a ton of dust out of my vents. That cured my temp problem.

Video chip; Usually caused by the driver. Tears in the high res when an app like Stellarium or GoogleEarth was running. Momentary hangs of the mouse or keyboard. Updating or downgrading the video driver solved it. If you disable desktop effects (which stops 3D graphics from being evoked) and your hangs stops then your video chip is probably the cause. Using"modinfo i915" (or what ever your video driver is named) shows what params, if any can be tinkered with. My i915 gives this:

[FONT=courier new][B]-$ modinfo i915[/B][/FONT]

filename:       /lib/modules/3.13.0-24-generic/kernel/drivers/gpu/drm/i915/i915.ko
license:        GPL and additional rights
description:    Intel Graphics
author:         Tungsten Graphics, Inc.
license:        GPL and additional rights
srcversion:     C6C6D0B5224D5DF3DCE1AE6
alias:          pci:v00008086d00000155sv*sd*bc03sc*i*
...<snip most aliases for device listings>
alias:          pci:v00008086d00003577sv*sd*bc03sc*i*
depends:        drm_kms_helper,drm,video,i2c-algo-bit
intree:         Y
vermagic:       3.13.0-24-generic SMP mod_unload modversions 
signer:         Magrathea: Glacier signing key
sig_key:        00:A5:A6:57:59:DE:47:4B:C5:C4:31:20:88:0C:1B:94:A5:39:F4:31
sig_hashalgo:   sha512
parm:           invert_brightness:Invert backlight brightness (-1 force normal, 0 machine defaults, 1 force inversion), please report PCI device ID, subsystem vendor and subsystem device ID to dri-devel@lists.freedesktop.org, if your machine needs it. It will then be included in an upcoming module version. (int)
parm:           modeset:Use kernel modesetting [KMS] (0=DRM_I915_KMS from .config, 1=on, -1=force vga console preference [default]) (int)
parm:           fbpercrtc:int
parm:           panel_ignore_lid:Override lid status (0=autodetect, 1=autodetect disabled [default], -1=force lid closed, -2=force lid open) (int)
parm:           powersave:Enable powersavings, fbc, downclocking, etc. (default: true) (int)
parm:           semaphores:Use semaphores for inter-ring sync (default: -1 (use per-chip defaults)) (int)
parm:           i915_enable_rc6:Enable power-saving render C-state 6. Different stages can be selected via bitmask values (0 = disable; 1 = enable rc6; 2 = enable deep rc6; 4 = enable deepest rc6). For example, 3 would enable rc6 and deep rc6, and 7 would enable everything. default: -1 (use per-chip default) (int)
parm:           i915_enable_fbc:Enable frame buffer compression for power savings (default: -1 (use per-chip default)) (int)
parm:           lvds_downclock:Use panel (LVDS/eDP) downclocking for power savings (default: false) (int)
parm:           lvds_channel_mode:Specify LVDS channel mode (0=probe BIOS [default], 1=single-channel, 2=dual-channel) (int)
parm:           lvds_use_ssc:Use Spread Spectrum Clock with panels [LVDS/eDP] (default: auto from VBT) (int)
parm:           vbt_sdvo_panel_type:Override/Ignore selection of SDVO panel mode in the VBT (-2=ignore, -1=auto [default], index in VBT BIOS table) (int)
parm:           reset:Attempt GPU resets (default: true) (bool)
parm:           enable_hangcheck:Periodically check GPU activity for detecting hangs. WARNING: Disabling this can cause system wide hangs. (default: true) (bool)
parm:           i915_enable_ppgtt:Enable PPGTT (default: true) (int)
parm:           enable_psr:Enable PSR (default: false) (int)
parm:           preliminary_hw_support:Enable preliminary hardware support. (int)
parm:           disable_power_well:Disable the power well when possible (default: true) (int)
parm:           enable_ips:Enable IPS (default: true) (int)
parm:           fastboot:Try to skip unnecessary mode sets at boot time (default: false) (bool)
parm:           enable_pc8:Enable support for low power package C states (PC8+) (default: true) (int)
parm:           pc8_timeout:Number of msecs of idleness required to enter PC8+ (default: 5000) (int)
parm:           prefault_disable:Disable page prefaulting for pread/pwrite/reloc (default:false). For developers only. (bool)

Setting a param in the grub boot line or in the options file can solve it:
http://xmodulo.com/2013/11/add-kerne...rub-linux.html
or, set an optin line in a *.conf file in /etc/modprobe.d/. Take a look at some of them for examples of how to do it. You can create your own somename.conf file in that directory and put your "option i915 someparam=somevalue" in it. If not "i915" then what ever kernel module your video driver uses.

A particular app; Some hangs and crashes are related to a particular app. Most of the tiime it is obvious, but sometimes, if you are running more than one app at the same time, determining which one, or combination, is responsible for the troubles can be problematic.

A RAM problem; Some RAM problems only appear when memory usage invades the blocks where the problem is, usually when running a memory intensive graphical application or having several apps open at once and switching frequently between them. Some problems are temperature dependent. Start the mem86+ RAM test and let it run for a day or two. If you have a heat gun block your air vent to let the computer get hotter and use the gun to test the air coming out of the vents. (It would be nice if memtest included a cpu temp display)

A couple of helpful sites:
http://nouveau.freedesktop.org/wiki/TroubleShooting/

http://nouveau.freedesktop.org/wiki/HangDiagnosis/

[oshunluvr]

Regarding the RAM error: Unless you're running a single stick; the best way to test RAM is remove one stick, then the other, until the problem goes away. If it doesn't, it's not the RAM.

[marshallbanana]

I had same issue and it was due to the nvidia driver. Try switching to use the nouvea driver and see if you keep getting the hangs. If not then at least you have located the source. If it still hangs periodically then the problem must be something else. Fortunately with Trusty the new hardware driver manager app makes this super easy.

(I am currently using the nouvea driver, until I can be bothered trying to fix the issue)

[joneall]

Video driver

Actually, I was having the problem with the new Nouveau (that's redundant) driver. I just switched to the NVidia one 2 hours ago to see if that was part of the problem. So far, so good, but it's too soon to tell.

Thanks for the tip!

[joneall]

hardware driver manager app

Fortunately with Trusty the new hardware driver manager app makes this super easy.

I can't find that. Where is it or what is it called?

Oops, I just found it.

[SteveRiley]

Another idea...

On my T520 with nVidia 4200M, I installed the latest 3.14 kernel from the Ubuntu mainline kernel PPA. I would get frequent hangs whenever my laptop was in its dock, which has two monitors connected via HDMI. I replaced the 3.14 kernel with a 3.15 kernel and the hangs disappeared.