Re: [PATCH RFC v2 4/4] block/mq-deadline: introduce min_async_depth

[Yu Kuai]

Hi,

在 2024/12/19 2:00, Bart Van Assche 写道:
> On 12/17/24 5:14 PM, Yu Kuai wrote:
> > I can't make this read-write, because set lower value will cause
> > problems for existing elevator, because wake_batch has to be
> > updated as well.
>
> Should the request queue perhaps be frozen before wake_batch is updated?

Yes, we should. The good thing is for now it's frozen already:
 - update nr_requests context;
 - switch elevator;

However, if you mean do this while writing async_depth, freeze queue
is not enough, we have to ping all the hctx as well by q->sysfs_lock,
which is not possible.

Or if you mean do this while write the new min_async_depth, then we have
to update wat_batch for all the queues in the system, too crazy for
me...

Thanks,
Kuai

> Thanks,
>
> Bart.
>
> .