Hello Carsten > Date: Thu, 3 Feb 2011 23:26:51 +0100 > From: C.Emde@xxxxxxxxx > To: nadaeck@xxxxxxxxxxx > Subject: Re: disk thread problem when using RT kernel > > Victor, > >> So if i understand well 'soft lock' is what i have described in my >> post, and what you were experiencing. >> >> The only solution is to wait then? > No, there is much more you can do. If you are willing to help in a > constructive way and provide traces and other debug material, we will be > glad to assist you to locate and fix your problem. Up to now, we are not > aware of any problem in the 2.6.33.7.2-rt30 "Latest Stable" real-time > kernel version (osadl.org/Latest-Stable), since it underwent more than > three months of heavy testing in our QA farm (osadl.org/QA). In general, > it is a good idea to follow Alan Cox's recommendations on how to post to > a mailing list -> > https://www.osadl.org/Eric-Raymond-How-to-ask-questions-the-s.questions-the-smart-way.0.html Sure I'm willing to help; thank you for your help; > > 1. Do not top-post; if you do, you will get much less help than you > would otherwise -> http://www.catb.org/~esr/jargon/html/T/top-post.html. Understood; i won't > > 2. Enable System Request (SysRq) > Edit /etc/sysctl.conf and change > kernel.sysrq = 0 > to > kernel.sysrq = 1 kernel.sysrq = 0 was not in /etcsysctl.conf, so I added manually kernel.sysrq = 1 in the file > This will enable SysRq at next reboot. To enable it while the computer > is running, type > echo 1>/proc/sys/kernel/sysrq > When SysRq is activated, the key combination Right-Alt/SysRq/ becomes > available. The SysRq key is the leftmost key of the group of three keys > to the right of F12. It is normally labeled "PrntScr" above and "SysRq" > below. You need to type the three keys altogether. The command > Right-Alt/SysRq/H, for example, displays help information, i.e. a list > of the various available commands. To try it out, type Right-Alt, then > type SysRq while you hold Right-Alt, then type H while you continue to > hold Right-Alt and SysRq. Hint: this may not work under a window > manager, since the key combination is filtered out. Use a virtual > console (Control/Left-Alt/F1). After you typed Right-Alt/SysRq/H, the > help info will be appended to the system log file such as: > > # tail -1 /var/log/messages > kernel: SysRq : HELP : loglevel(0-9) reBoot Crash terminate-all-tasks(E) > memory-full-oom-kill(F) kill-all-tasks(I) thaw-filesystems(J) saK > show-backtrace-all-active-cpus(L) show-memory-usage(M) > nice-all-RT-tasks(N) powerOff show-registers(P) show-all-timers(Q) unRaw > Sync show-task-states(T) Unmount show-blocked-tasks(W) > dump-ftrace-buffer(Z) It worked > > The Key combination S-U-B (Right-Alt/SysRq/S - Right-Alt/SysRq/U - > Right-Alt/SysRq/B) is worth to remember - in many cases, it will reboot > a crashed system gracefully, since it flushes the disk cache, unmounts > the disk and then reboots the system. You will no longer hate to do a > forced shutdown of the system. > > When the system "hangs", the commands Right-Alt/SysRq/L, > Right-Alt/SysRq/M, Right-Alt/SysRq/T etc. may be helpful to check out > what the system is doing when the system has crashed and there is hope > it still has some life in it. > > 3. Enable a serial console > To print system and kernel messages, add > ignore_log_level earlyprintk=ttyS0,115200 > and > console=ttyS0,115200 console=tty0 > to the kernel boot parameters. Connect the system under test to another > computer (use a null-modem cable) and minicom to it. If the system does > not have a serial interface, but has an empty PCI slot, consider to > purchase a PCI serial adapter. They are available for less than $25 > (US). When the system hangs, the serial console may contain useful > information such as kernel crash dumps. > > 4. Next time you post a bug report, please provide the debug and trace > information that you were able to generate from the output of the serial > console or from SysRq. > > > Hope this helps, > > Carsten. Thanks i'll try do all that; PS Please one more thing : before i understand that Right-Alt had to be replaced (in my case) by AltGr, I've been trying different combination of keys (right, arrow, Left-Alt, and others); right away i was off connection and i have bit networking problems on the whole pc : wireless is disabled, and eth0 is gone; fortunately, i can connect on eth1; this happens **on the whole laptop** (even my other ubuntu on another disk partition, or the ubuntu from the live usb stick have the same problem; it's like the previous network interface has been "burned"...); this happened just after the combination key test... I'll post it somewhere else where it is more appropriate, but i just wanted to ask if it sounded familiar... Thanks again Victor -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
