On 15/02/2019 16:58, Edwin Török wrote: > On 15/02/2019 16:08, Christine Caulfield wrote: >> On 15/02/2019 13:06, Edwin Török wrote: >>> I tried again with 'debug: trace', lots of process pause here: >>> https://clbin.com/ZUHpd >>> >>> And here is an strace running realtime prio 99, a LOT of epoll_wait and >>> sendmsg (gz format): >>> https://clbin.com/JINiV >>> >>> It detects large numbers of members left, but I think this is because >>> the corosync on those hosts got similarly stuck: >>> Feb 15 12:51:07 localhost corosync[29278]: [TOTEM ] A new membership >>> (10.62.161.158:3152) was formed. Members left: 2 14 3 9 5 11 4 12 8 13 7 >>> 1 10 >>> Feb 15 12:51:07 localhost corosync[29278]: [TOTEM ] Failed to receive >>> the leave message. failed: 2 14 3 9 5 11 4 12 8 13 7 1 10 >>> >>> Looking on another host that is still stuck 100% corosync it says: >>> https://clbin.com/6UOn6 >>> >> >> Thanks, that's really quite odd. I have vague recollections of a problem >> where corosync was spinning on epoll without reading anything but can't >> find the details at the moment, annoying. >> >> Some thing you might be able to try that might help. >> >> 1) is is possible to run without sbd. Sometimes too much polling from >> clients can cause odd behaviour >> 2) is it possible to try with a different kernel? We've tried a vanilla >> 4.19 and it's fine, but not with the Xen patches obviously > > I'll try with some bare-metal upstream distros and report back the repro > steps if I can get it to reliably repro, hopefully early next week, it > is unlikely I'll get a working repro today. > >> 3) Does running corosync with the -p option help? > > Yes, with "-p" I was able to run cluster create/GFS2 plug/unplug/destroy > on 16 physical hosts in a loop for an hour with any crashes (previously > it would crash within minutes). > > I found another workaround too: > echo NO_RT_RUNTIME_SHARE >/sys/kernel/debug/sched_features > > This makes the 95% realtime process CPU limit from > sched_rt_runtime_us/sched_rt_period_us apply per core, instead of > globally, so there would be 5% time left for non-realtime tasks on each > core. Seems to be enough to avoid the livelock, I was not able to > observe corosync using high CPU % anymore. > Still got more tests to run on this over the weekend, but looks promising. > > This is a safety layer of course, to prevent the system from fencing if > we encounter high CPU usage in corosync/libq. I am still interested in > tracking down the corosync/libq issue as it shouldn't have happened in > the first place. >
That's helpful to know. Does corosync still use lots of CPU time in this situation (without RT) or does it behave normally? >> >> Is there any situation where this has worked? either with different >> components or different corosync.conf files? >> >> Also, and I don't think this is directly related to the issue, but I can >> see configuration reloads happening from 2 nodes every 5 seconds. It's >> very odd and maybe not what you want! > > The configuration reloads are a way of triggering this bug reliably, I > should've mentioned that earlier > (the problem happens during a configuration reload, but not always, and > by doing configuration reloads in a loop that just add/remove one node > the problem can be triggered reliably within minutes). > > I've been trying this on my (KVM) virtual machines today but I can't reproduce it on a Standard RHEL-7, so I'm interested to see how you get on with a different kernel. Chrissie _______________________________________________ Users mailing list: Users@clusterlabs.org https://lists.clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org