> On Oct 25, 2024, at 15:50, Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote: > > Hi, > > +CC Tejun > > 在 2024/10/24 12:35, Muchun Song 写道: >> When rq_qos_wait() is first introduced, it is easy to understand. But >> with some bug fixes applied, it is not easy for newcomers to understand >> the whole logic under those fixes. In this patch, rq_qos_wait() is >> refactored and more comments are added for better understanding. There >> are 4 points for the improvement: >> 1) Use waitqueue_active() instead of wq_has_sleeper() to eliminate >> unnecessary memory barrier in wq_has_sleeper() which is supposed >> to be used in waker side. In this case, we do need the barrier. >> So use the cheaper one to locklessly test for waiters on the queue. >> 2) There is already a macro DEFINE_WAIT_FUNC() to declare a >> wait_queue_entry with a specified waking function. But there is not >> a counterpart for initializing one wait_queue_entry with a >> specified waking function. So introducing init_wait_func() for >> this, which also could be used elsewhere (like filemap.c). It can >> be used in rq_qos_wait() to use default_wake_function() to wake up >> waiters, which could remove ->task field from rq_qos_wait_data. > > I think it's better to cook point 2 as a seperate patch. > > Whether or not, this patch LGTM. Either is OK for me. I can update this in v2. > Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx> Thanks for your review. Thanks, Muchun
