[lttng-dev] 'call_rcu' unstable?

[Mathieu Desnoyers]

* zs (84500316 at qq.com) wrote:
> Hi list,
> 
> I found a big problem in my product, that use urcu 0.7.5. My program cost too mutch CPU in the funtion 'update_counter_and_wait:uruc.c:247', and I use gdb to see to *wait_loops*, it says -167777734. The CPU usage grows up from 1% to 100% in one day!
> 
> 
> Here is the sample code to show how I use urcu library:
> 
> #include <urcu.h>
> 
> thread ()
> {
> rcu_register_thread();
> 
> for (;;) {
> rcu_read_lock();
> xxx
> rcu_read_unlock();

Please triple-check that all your rcu_read_lock() and rcu_read_unlock()
are balanced (no double-unlock, nor missing unlock for each lock taken).

The type of problem you get would happen in such a case.

Thanks,

Mathieu

> }
> }
> 
> main()
> {
> rcu_init();
>   pthread_create(, , , , thread);
> 
> rcu_register_thread();
> for (;;)
> {
>  if (xxx)
>    call_rcu();
> }
> 
> }
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-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com