Hello all,
I am seeing an rcuc "osnoise" on an isolated CPU (#4) that should have
(per-cpu) rcuc offloaded to, and polled by, other CPUs.
Note this is with vmlinuz-6.9.10-rt5.
I did not expect "rcuc/4" to actually run on CPU #4.
Then I found the email thread "Wakes of the rcuc/ thread on isolated
CPUs." and also tried with rcutree.nohz_full_patience_delay=1000.
What could be the misconfiguration or issue?
[ 0.011004] Kernel command line: [ 0.000000] Command line:
BOOT_IMAGE=/boot/vmlinuz-6.9.10-rt5 <...>
isolcpus=domain,managed_irq,2-7,10-15 nohz_full=2-7,10-15
rcu_nocbs=2-7,10-15 rcu_nocb_poll
rcutree.nohz_full_patience_delay=1000 <...>
[ 0.033362] rcu: Offload RCU callbacks from CPUs: 2-7,10-15.
[ 0.033362] rcu: Poll for callbacks from no-CBs CPUs.
sudo LD_LIBRARY_PATH=/usr/local/lib64 /usr/local/usr/bin/rtla osnoise
top -a 20 -c 4 -e osnoise; cat osnoise_trace.txt
cat osnoise_trace.txt
# tracer: osnoise
#
# _-------=> irqs-off
# / _------=> need-resched
# | / _-----=> need-resched-lazy
# || / _----=> hardirq/softirq
# ||| / _---=> preempt-depth
# |||| / _--=> preempt-lazy-depth
# ||||| / _-=> migrate-disable
# |||||| /
MAX
# ||||| /
SINGLE Interference counters:
# ||||||| RUNTIME
NOISE %% OF CPU NOISE +-----------------------------+
# TASK-PID CPU# ||||||| TIMESTAMP IN US IN
US AVAILABLE IN US HW NMI IRQ SIRQ THREAD
# | | | ||||||| | |
| | | | | | | |
osnoise/4-1553 [004] dNh11 181.384695: irq_noise:
local_timer:236 start 181.384689739 duration 4120 ns
rcuc/4-64 [004] d..3. 181.384707: thread_noise:
rcuc/4:64 start 181.384702999 duration 3180 ns
osnoise/4-1553 [004] ....1 181.384708: sample_threshold:
start 181.384686979 duration 20360 ns interference 2
Regards,
Leon.
