I started out this morning by trying to run DevStack on the latest
"net' kernel and it looks like I am hanging on some sort of locking
problem with RabbitMQ. Specifically I am seeing one CPU jump to 100%
with perf showing that I am spinning on a lock.
I'm working to bisect it now, but just thought I would put it out
there if anybody had already root caused this issue. Below is a few
traces to the spin lock call on the spinning CPU:
- 18.81% 18.81% beam.smp [kernel.vmlinux] [k] _raw_spin_lock_irqsave
- _raw_spin_lock_irqsave
- 32.86% add_wait_queue
n_tty_write
tty_write
do_loop_readv_writev
do_readv_writev
vfs_writev
do_writev
sys_writev
do_syscall_64
return_from_SYSCALL_64
__libc_writev
- 32.49% remove_wait_queue
n_tty_write
tty_write
do_loop_readv_writev
do_readv_writev
vfs_writev
do_writev
sys_writev
do_syscall_64
return_from_SYSCALL_64
__libc_writev
- 31.71% __wake_up
tty_write_unlock
tty_write
do_loop_readv_writev
do_readv_writev
vfs_writev
do_writev
sys_writev
do_syscall_64
return_from_SYSCALL_64
__libc_writev
- 1.96% n_tty_write
tty_write
do_loop_readv_writev
do_readv_writev
vfs_writev
do_writev
sys_writev
do_syscall_64
return_from_SYSCALL_64
__libc_writev
- 0.87% tty_write_unlock
tty_write
do_loop_readv_writev
do_readv_writev
vfs_writev
do_writev
sys_writev
do_syscall_64
return_from_SYSCALL_64
__libc_writev
