Bug 118221
| Summary: | After CPU hotplug, cores remain idle | ||
|---|---|---|---|
| Product: | Process Management | Reporter: | Davide (baldiniebaldini) |
| Component: | Other | Assignee: | process_other |
| Status: | NEW --- | ||
| Severity: | normal | CC: | baldiniebaldini |
| Priority: | P1 | ||
| Hardware: | x86-64 | ||
| OS: | Linux | ||
| Kernel Version: | 4.5.4 vanilla | Subsystem: | |
| Regression: | No | Bisected commit-id: | |
To rephrase concisely:
after executing
for c in /sys/devices/system/cpu/cpu*/online; do
echo 0 >$c
echo 1 >$c
done
all currently-running processes, as well as newly launched processes, executing from within an LXC environment remain bound to CPU 0. They won't use cores above cpu0.
|
--- Synopsis When I do: for c in /sys/devices/system/cpu/cpu*/online; do echo 0 >$c done # sleep 60 for c in /sys/devices/system/cpu/cpu*/online; do echo 1 >$c done cores above 0 remain idle, meaning that no threads appear to be assigned to them. I run a several dummy processes, like 'yes >/dev/null' and `top` reports a cumulative cpu percentage usage of only 100% among all processes (8 cores available), while the 60-seconds load average is steadily 8. This: cat /sys/devices/system/cpu/cpu*/online replies '1' for every cpu 1 to 7. Dmesg (*) appended at bottom. ---- Hardware: Dual xeon l5410, 4 cores per chip. --- Miscellanea - LXC is in use; - KVM module is mounted; - kernel is configured to not hotswap core 0 (CONFIG_BOOTPARAM_HOTPLUG_CPU0 false); - the same problem happens on kernel 4.1.1 vanilla. (*) Dmeseg: [ 2214.621148] smpboot: CPU 1 is now offline [ 2214.711114] smpboot: CPU 2 is now offline [ 2214.801249] smpboot: CPU 3 is now offline [ 2214.901186] smpboot: CPU 4 is now offline [ 2215.010119] Broke affinity for irq 25 [ 2215.011273] smpboot: CPU 5 is now offline [ 2215.110125] Broke affinity for irq 25 [ 2215.111162] smpboot: CPU 6 is now offline [ 2215.220102] Broke affinity for irq 15 [ 2215.220123] Broke affinity for irq 25 [ 2215.221157] smpboot: CPU 7 is now offline [ 2231.230726] x86: Booting SMP configuration: [ 2231.230731] smpboot: Booting Node 0 Processor 1 APIC 0x4 [ 2231.340393] smpboot: Booting Node 0 Processor 2 APIC 0x1 [ 2231.430533] smpboot: Booting Node 0 Processor 3 APIC 0x5 [ 2231.530515] smpboot: Booting Node 0 Processor 4 APIC 0x2 [ 2231.640622] smpboot: Booting Node 0 Processor 5 APIC 0x6 [ 2231.730666] smpboot: Booting Node 0 Processor 6 APIC 0x3 [ 2231.860766] smpboot: Booting Node 0 Processor 7 APIC 0x7