On Wed, Jan 12, 2022 at 12:18:53PM +0800, QiuLaibin wrote:
> On 2022/1/11 22:15, Andy Shevchenko wrote:
> > On Tue, Jan 11, 2022 at 10:02:16PM +0800, Laibin Qiu wrote:
...
> > > + if (test_bit(QUEUE_FLAG_HCTX_ACTIVE, &q->queue_flags) ||
> > > + test_and_set_bit(QUEUE_FLAG_HCTX_ACTIVE, &q->queue_flags)) {
> >
> > Whoever wrote this code did too much defensive programming, because the first
> > conditional doesn't make much sense here. Am I right?
> >
> I think because this judgement is in the general IO process, there are also
> some performance considerations here.
I didn't buy this. Is there any better argument why you need redundant
test_bit() call?
> > > + return true;
> > > } else {
> >
> > > + if (test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) ||
> > > + test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) {
> >
> > Ditto.
> >
> > > + return true;
> > > }
...
> > > + unsigned int wake_batch = clamp_t(unsigned int,
> > > + (sbq->sb.depth + users - 1) / users, 4U, SBQ_WAKE_BATCH);
> >
> >
> > unsigned int wake_batch;
> >
> > wake_batch = clamp_val((sbq->sb.depth + users - 1) / users, 4, SBQ_WAKE_BATCH);
> > ...
> >
> > is easier to read, no?
>
> Here I refer to the calculation method in sbq_calc_wake_batch(). And I will
> separate the definition from the calculation in V5.
I'm not sure I understand how it's related to the style changes I proposed.
I haven't changed any logic behind.
--
With Best Regards,
Andy Shevchenko
