Re: [PATCH] RDMA/rxe: Replace use of system_unbound_wq with system_dfl_wq

[Zhu Yanjun <yanjun.zhu@linux.dev>]

在 2026/3/16 13:13, Leon Romanovsky 写道:
> On Fri, Mar 13, 2026 at 04:40:23PM +0100, Marco Crivellari wrote:
>> This patch continues the effort to refactor workqueue APIs, which has begun
>> with the changes introducing new workqueues and a new alloc_workqueue flag:
>>
>>     commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
>>     commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")
>>
>> The point of the refactoring is to eventually alter the default behavior of
>> workqueues to become unbound by default so that their workload placement is
>> optimized by the scheduler.
>>
>> Before that to happen, workqueue users must be converted to the better named
>> new workqueues with no intended behaviour changes:
>>
>>     system_wq -> system_percpu_wq
>>     system_unbound_wq -> system_dfl_wq
>>
>> This way the old obsolete workqueues (system_wq, system_unbound_wq) can be
>> removed in the future.
> 
> I recall earlier efforts to replace system workqueues with per‑driver queues,
> because unloading a driver forces a flush of the entire system workqueue,
> which is undesirable for overall system behavior.
> 
> Wouldn't it be better to introduce a local workqueue here and use that instead?

Thanks.

1.The initialization should be:

my_wq = alloc_workqueue("my_driver_queue", WQ_UNBOUND | WQ_MEM_RECLAIM, 0);
if (!my_wq)
     return -ENOMEM;

2. The Submission should be:

queue_work(my_wq, &my_work);

3. Destroy should be:

destroy_workqueue()

Thanks,
Zhu Yanjun

> 
> Thanks
> 
>>
>> Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/
>> Suggested-by: Tejun Heo <tj@kernel.org>
>> Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
>> ---
>>   drivers/infiniband/sw/rxe/rxe_odp.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/infiniband/sw/rxe/rxe_odp.c b/drivers/infiniband/sw/rxe/rxe_odp.c
>> index bc11b1ec59ac..d440c8cbaea5 100644
>> --- a/drivers/infiniband/sw/rxe/rxe_odp.c
>> +++ b/drivers/infiniband/sw/rxe/rxe_odp.c
>> @@ -545,7 +545,7 @@ static int rxe_ib_advise_mr_prefetch(struct ib_pd *ibpd,
>>   		work->frags[i].mr = mr;
>>   	}
>>   
>> -	queue_work(system_unbound_wq, &work->work);
>> +	queue_work(system_dfl_wq, &work->work);
>>   
>>   	return 0;
>>   
>> -- 
>> 2.53.0
>>