On Fri, Feb 19, 2016 at 9:00 AM, Christian Rohmann <crohmann@xxxxxxxxxxxxx> wrote: > Hey liubo, > > thanks for the quick response. > > On 02/18/2016 05:59 PM, Liu Bo wrote: >>> Apparently also with 4.4 there is some sort of blocking happening ... >>> > just at 38580: >> OK, what does 'sysrq-w' say? > > The problem has not appeared again for some time. Do I need to catch it > right when it happens? If so, what evidence should I collect and how? It's uncertain how your kernel is built so full documentation is here: https://www.kernel.org/doc/Documentation/sysrq.txt Anytime before or during the problem: echo 1 >/proc/sys/kernel/sysrq Once blocked tasks show up: echo w > /proc/sysrq-trigger journalctl -k -o short-monotonic -l > journal_sysrqw.txt ## example If you're not on a systemd system, all of this should get dumped into rsyslogd messages, so you can go in there and extract the current boot into a file to attach. It should also appear in dmesg of course but sometimes the output is bigger than the default kernel message buffer. -- Chris Murphy -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
