Re: [PATCH v2] block: flush all throttled bios when deleting the cgroup

[Li Lingfeng]

在 2024/7/2 22:25, Michal Koutný 写道:
> On Fri, Jun 28, 2024 at 10:04:20AM GMT, Li Lingfeng <lilingfeng@xxxxxxxxxxxxxxx> wrote:
> > I think it may be more appropriate to remove the limit of bios after the
> > cgroup is deleted, rather than let the bios continue to be throttled by a
> > non-existent cgroup.
> I'm not that familiar with this part -- can this also happen for IOs
> submitted by an exited task? (In contrast to a running task migrated
> elsewhere.)
Yes, IOs will be throttled no matter whether the task that delivers them
exits.
> > If the limit is set too low, and the original cgourp has been deleted, we
> > now have no way to make the bios complete immediately, but to wait for the
> > bios to slowly complete under the limit.
> It makes some sense, it's not unlike reparenting of memcg objects, IIRC
> flushed bios would actually be passed to a parent throtl_grp, right?
Yes, flushed bios would be throttled by the parent throtl_grp.
> Thanks,
> Michal