Messages in this thread | | | Subject | Re: [PATCH -next 10/11] block, bfq: decrease 'num_groups_with_pending_reqs' earlier | From | "yukuai (C)" <> | Date | Wed, 13 Apr 2022 19:40:32 +0800 |
| |
在 2022/04/13 19:28, Jan Kara 写道: > On Sat 05-03-22 17:12:04, Yu Kuai wrote: >> Currently 'num_groups_with_pending_reqs' won't be decreased when >> the group doesn't have any pending requests, while some child group >> still have pending requests. The decrement is delayed to when all the >> child groups doesn't have any pending requests. >> >> For example: >> 1) t1 issue sync io on root group, t2 and t3 issue sync io on the same >> child group. num_groups_with_pending_reqs is 2 now. >> 2) t1 stopped, num_groups_with_pending_reqs is still 2. io from t2 and >> t3 still can't be handled concurrently. >> >> Fix the problem by decreasing 'num_groups_with_pending_reqs' >> immediately upon the weights_tree removal of last bfqq of the group. >> >> Signed-off-by: Yu Kuai <yukuai3@huawei.com> > > So I'd find the logic easier to follow if you completely removed > entity->in_groups_with_pending_reqs and did updates of > bfqd->num_groups_with_pending_reqs like: > > if (!bfqg->num_entities_with_pending_reqs++) > bfqd->num_groups_with_pending_reqs++; > Hi,
Indeed, this is an excellent idle, and much better than the way I did.
Thanks, Kuai
> and similarly on the remove side. And there would we literally two places > (addition & removal from weight tree) that would need to touch these > counters. Pretty obvious and all can be done in patch 9. > > Honza >
| |