Messages in this thread | | | Subject | Re: [PATCH 5/7] module: take rcu_read_lock_sched() for /proc read | From | Eric Dumazet <> | Date | Thu, 15 Mar 2012 09:18:49 -0700 |
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On Thu, 2012-03-15 at 22:48 +0800, Cong Wang wrote: > In the seq file operations, it still hold module_mutex for just reading > the module list, switch to rcu_read_lock_sched() too. >
Why is it needed ?
1) insmod/rmmod/lsmod is hardly in fast path.
2) after a mutex_lock(), a task is still preemptible after rcu_read_lock_sched(), preemption is disabled
with NR_CPUS=4096, getting module refcounts is _very_ slow
RCU doesnt fit every workload.
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