On 2/24/20 8:50 AM, Pavel Begunkov wrote: > On 24/02/2020 18:46, Jens Axboe wrote: >> On 2/24/20 8:44 AM, Pavel Begunkov wrote: >>>> Fine like this, though easier if you inline the patches so it's easier >>>> to comment on them. >>>> >>>> Agree that the first patch looks fine, though I don't quite see why >>>> you want to pass in opcode as a separate argument as it's always >>>> req->opcode. Seeing it separate makes me a bit nervous, thinking that >>>> someone is reading it again from the sqe, or maybe not passing in >>>> the right opcode for the given request. So that seems fragile and it >>>> should go away. >>> >>> I suppose it's to hint a compiler, that opcode haven't been changed >>> inside the first switch. And any compiler I used breaks analysis there >>> pretty easy. Optimising C is such a pain... >> >> But if the choice is between confusion/fragility/performance vs obvious >> and safe, then I'll go with the latter every time. We should definitely >> not pass in req and opcode separately. > > Yep, and even better to go with the latter, and somehow hint, that it won't > change. Though, never found a way to do that. Have any tricks in a sleeve? We could make it const and just make the assignment a bit hackier... Apart from that, don't have any tricks up my sleeve. -- Jens Axboe
