Re: [PATCH -next v5 4/8] blk-throttle: fix io hung due to config updates

[Yu Kuai]

在 2022/06/24 0:26, Michal Koutný 写道:
> On Thu, Jun 23, 2022 at 08:27:11PM +0800, Yu Kuai <yukuai3@xxxxxxxxxx> wrote:
> > > Here we may allow to dispatch a bio above current slice's
> > > calculate_bytes_allowed() if bytes_skipped is already >0.
> >
> > Hi, I don't expect that to happen. For example, if a bio is still
> > throttled, then old slice is keeped with proper 'bytes_skipped',
> > then new wait time is caculated based on (bio_size - bytes_skipped).
> >
> > After the bio is dispatched(I assum that other bios can't preempt),
>
> With this assumptions it adds up as you write. I believe we're in
> agreement.
>
> It's the same assumption I made below (FIFO everywhere, i.e. no
> reordering). So the discussed difference shouldn't really be negative
> (and if the assumption didn't hold, so the modular arithmetic yields
> corerct bytes_skipped value).
Yes, nice that we're in aggreement.

I'll wait to see if Tejun has any suggestions.

Thanks,
Kuai
> Michal
> .