Userspace starving kernel threads for CPU cycle.
Àbéjídé Àyodélé
abejideayodele at gmail.com
Sat Jun 9 00:05:33 EDT 2018
The short answer: 'man 7 sched'
Thanks I read this and I think I might still be confused. I am using cgroups
and have cpu.cfs_quota_us configured as 2300000 and cpu.cfs_period_us
configured as 100000 for 3 different cgroups of, all of these I assume
equates
69 cpus along with a couple of other cgroups with cpu.cfs_quota_us
configured
on a 80 cpu machine which is why I made my original guess.
The first question is, of course: "Did you see any actual evidence of kernel
threads being starved?"
I have a couple of very similar machines with similar workloads and observed
the below type of messages in dmesg on several of them:
rcu_sched detected stalls on CPUs
Sending NMI from CPU 43 to CPUs 14
watchdog: BUG: soft lockup - CPU#26 stuck for 22s [migration/54:335]
ixgbe 0000:19:00.1 eno2: initiating reset due to tx timeout
Which is why I have this hypothesis.
I am still unclear if the cgroup group controller makes guarantees such that
tasks in the cgroup cannot be preempted even if a kernel thread requires cpu
time.
Thanks for your time!
Abejide Ayodele
It always seems impossible until it's done. --Nelson Mandela
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20180608/9253698f/attachment-0001.html>
More information about the Kernelnewbies
mailing list