在 2024/9/24 7:52, Andi Kleen 写道: >> Thanks for the suggestions, I will experiment with a read-write lock, meanwhile, >> adding the documentation and testing for the lockless scheme. > > Read-write locks are usually not worth it for short critical sections, > in fact they can be slower due to cache line effects. OK, I will start from a simple spinlock. > >> Sorry, I may not probably get the point clear here, and it would be very >> nice if more details are provided for the concern. Do you mean it's necessary >> to make the if-body excution exclusive among the CPUs? If that's the case, >> I guess the test_and_put_task_slot() is the equvialent to the race condition >> check. test_and_put_task_slot() uses a compare and exchange operation on the >> slot_ref of utask instance. Regardless of the work type being performed by >> other CPU, it will always bail out unless the slot_ref has a value of one, >> indicating the utask is free to access from local CPU. > > What I meant is that the typical pattern for handling races in destruction > is to detect someone else is racing and then let it do the destruction > work or reacquire the resource (so just bail out). Agreed. > > But that's not what you're doing here, in fact you're adding a > completely new code path that has different semantics? I haven't checked > all the code, but it looks dubious. Andi, I've just sent v2. Looking forward to your feedback. Thanks. https://lore.kernel.org/all/20240927094549.3382916-1-liaochang1@xxxxxxxxxx/ > > -Andi > -- BR Liao, Chang
