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    rcu: Add tracing data to support queueing models · 269dcc1c
    Paul E. McKenney 提交于
    The current tracing data is not sufficient to deduce the average time
    that a callback spends waiting for a grace period to end.  Add three
    per-CPU counters recording the number of callbacks invoked (ci), the
    number of callbacks orphaned (co), and the number of callbacks adopted
    (ca).  Given the existing callback queue length (ql), the average wait
    time in absence of CPU hotplug operations is ql/ci.  The units of wait
    time will be in terms of the duration over which ci was measured.
    
    In the presence of CPU hotplug operations, there is room for argument,
    but ql/(ci-co+ca) won't steer you too far wrong.
    
    Also fixes a typo called out by Lucas De Marchi <lucas.de.marchi@gmail.com>.
    Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
    269dcc1c
rcutree_trace.c 9.7 KB