Re: [PATCH v8 15/19] locking/rwsem: Adaptive disabling of reader optimistic spinning

[Waiman Long]

On 6/4/19 5:20 AM, Peter Zijlstra wrote:
> On Mon, May 20, 2019 at 04:59:14PM -0400, Waiman Long wrote:
>> @@ -286,6 +325,7 @@ struct rwsem_waiter {
>>  	struct task_struct *task;
>>  	enum rwsem_waiter_type type;
>>  	unsigned long timeout;
>> +	long last_rowner;
>>  };
>>  #define rwsem_first_waiter(sem) \
>>  	list_first_entry(&sem->wait_list, struct rwsem_waiter, list)
>> +static inline bool rwsem_reader_phase_trylock(struct rw_semaphore *sem,
>> +					      long last_rowner)
>> +static inline bool rwsem_reader_phase_trylock(struct rw_semaphore *sem,
>> +					      unsigned long last_rowner)
>> +	waiter.last_rowner = atomic_long_read(&sem->owner);
> That's somewhat inconsistent wrt the type. I'll make it unsigned long,
> as that is what makes most sense, given there's a pointer inside.

Thank for spotting that, I will fix it.

-Longman