From: Jan Kara <jack@suse.cz>
To: "yukuai (C)" <yukuai3@huawei.com>
Cc: Jan Kara <jack@suse.cz>,
paolo.valente@linaro.org, axboe@kernel.dk, tj@kernel.org,
linux-block@vger.kernel.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, yi.zhang@huawei.com
Subject: Re: [PATCH -next v2 2/5] block, bfq: add fake weight_counter for weight-raised queue
Date: Mon, 25 Apr 2022 18:16:50 +0200 [thread overview]
Message-ID: <20220425161650.xzyijgkb5yzviea3@quack3.lan> (raw)
In-Reply-To: <a27b8c79-867f-9253-84db-1d39c964b3ed@huawei.com>
Hello!
On Mon 25-04-22 21:34:16, yukuai (C) wrote:
> 在 2022/04/25 17:48, Jan Kara 写道:
> > On Sat 16-04-22 17:37:50, Yu Kuai wrote:
> > > Weight-raised queue is not inserted to weights_tree, which makes it
> > > impossible to track how many queues have pending requests through
> > > weights_tree insertion and removel. This patch add fake weight_counter
> > > for weight-raised queue to do that.
> > >
> > > Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> >
> > This is a bit hacky. I was looking into a better place where to hook to
> > count entities in a bfq_group with requests and I think bfq_add_bfqq_busy()
> > and bfq_del_bfqq_busy() are ideal for this. It also makes better sense
> > conceptually than hooking into weights tree handling.
>
> bfq_del_bfqq_busy() will be called when all the reqs in the bfqq are
> dispatched, however there might still some reqs are't completed yet.
>
> Here what we want to track is how many bfqqs have pending reqs,
> specifically if the bfqq have reqs are't complted.
>
> Thus I think bfq_del_bfqq_busy() is not the right place to do that.
Yes, I'm aware there will be a difference. But note that bfqq can stay busy
with only dispatched requests because the logic in __bfq_bfqq_expire() will
not call bfq_del_bfqq_busy() if idling is needed for service guarantees. So
I think using bfq_add/del_bfqq_busy() would work OK.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2022-04-25 16:17 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-16 9:37 [PATCH -next v2 0/5] support concurrent sync io for bfq on a specail occasion Yu Kuai
2022-04-16 9:37 ` [PATCH -next v2 1/5] block, bfq: cleanup bfq_weights_tree add/remove apis Yu Kuai
2022-04-25 9:37 ` Jan Kara
2022-04-16 9:37 ` [PATCH -next v2 2/5] block, bfq: add fake weight_counter for weight-raised queue Yu Kuai
2022-04-25 9:48 ` Jan Kara
2022-04-25 13:34 ` yukuai (C)
2022-04-25 13:55 ` yukuai (C)
2022-04-25 16:26 ` Jan Kara
2022-04-25 16:16 ` Jan Kara [this message]
2022-04-26 1:49 ` yukuai (C)
2022-04-26 7:40 ` Jan Kara
2022-04-26 8:27 ` yukuai (C)
2022-04-26 9:15 ` Jan Kara
2022-04-26 11:27 ` yukuai (C)
2022-04-26 14:04 ` Paolo Valente
2022-04-16 9:37 ` [PATCH -next v2 3/5] bfq, block: record how many queues have pending requests in bfq_group Yu Kuai
2022-04-16 9:37 ` [PATCH -next v2 4/5] block, bfq: refactor the counting of 'num_groups_with_pending_reqs' Yu Kuai
2022-04-16 9:37 ` [PATCH -next v2 5/5] block, bfq: do not idle if only one cgroup is activated Yu Kuai
2022-04-24 2:44 ` [PATCH -next v2 0/5] support concurrent sync io for bfq on a specail occasion yukuai (C)
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