• Paul E. McKenney's avatar
    rcu: Exclude near-simultaneous RCU CPU stall warnings · 8c42b1f3
    Paul E. McKenney authored
    There is a two-jiffy delay between the time that a CPU will self-report
    an RCU CPU stall warning and the time that some other CPU will report a
    warning on behalf of the first CPU.  This has worked well in the past,
    but on busy systems, it is possible for the two warnings to overlap,
    which makes interpreting them extremely difficult.
    
    This commit therefore uses a cmpxchg-based timing decision that
    allows only one report in a given one-minute period (assuming default
    stall-warning Kconfig parameters).  This approach will of course fail
    if you are seeing minute-long vCPU preemption, but in that case the
    overlapping RCU CPU stall warnings are the least of your worries.
    Reported-by: default avatarDmitry Vyukov <dvyukov@google.com>
    Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
    8c42b1f3
tree.c 128 KB