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From: "Michal Koutný" <mkoutny@suse.com>
To: Tejun Heo <tj@kernel.org>
Cc: hannes@cmpxchg.org, clm@fb.com, dennisz@fb.com, newella@fb.com,
	lizefan@huawei.com, axboe@kernel.dk, josef@toxicpanda.com,
	Josef Bacik <jbacik@fb.com>,
	kernel-team@fb.com, Rik van Riel <riel@surriel.com>,
	cgroups@vger.kernel.org, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Paolo Valente <paolo.valente@linaro.org>
Subject: Re: [PATCH 08/10] blkcg: implement blk-iocost
Date: Tue, 10 Sep 2019 14:55:14 +0200
Message-ID: <20190910125513.GA6399@blackbody.suse.cz> (raw)
In-Reply-To: <20190828220600.2527417-9-tj@kernel.org>

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Hello.

On Wed, Aug 28, 2019 at 03:05:58PM -0700, Tejun Heo <tj@kernel.org> wrote:
> diff --git a/block/blk-iocost.c b/block/blk-iocost.c
> [...]
> +static struct cftype ioc_files[] = {
> +		.name = "weight",
> [...]
This adds the generic io.weight attribute. How will this compose with
the weight from IO schedulers? (AFAIK, only BFQ allows proportional
control as of now. +CC Paolo.)

I see this attributes are effectively per-cgroup per-device. Apparently,
one device should have only one weight across hierarchy. Would it make
sense to have io.bfq.weight and io.cost.weight with disjunctive devices?

(Alas, I have no idea how to make the users of io.weight happy, when
proportionality control mechanism seems orthogonal to the weight.
(Vector weights?))


> +		.name = "cost.qos",
> +		.flags = CFTYPE_ONLY_ON_ROOT,
> [...]
> +		.name = "cost.model",
> +		.flags = CFTYPE_ONLY_ON_ROOT,
I'm concerned that these aren't true cgroup attributes. The root cgroup
would act as container for global configuration options. Wouldn't these
values better fit as (configurable) attributes of the respective
devices?

Secondly, how is CFTYPE_ONLY_ON_ROOT supposed to be presented in cgroup
namespaces?

Thanks,
Michal

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  parent reply index

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-28 22:05 [PATCHSET v3 block/for-linus] IO cost model based work-conserving porportional controller Tejun Heo
2019-08-28 22:05 ` [PATCH 01/10] blkcg: pass @q and @blkcg into blkcg_pol_alloc_pd_fn() Tejun Heo
2019-08-28 22:05 ` [PATCH 02/10] blkcg: make ->cpd_init_fn() optional Tejun Heo
2019-08-28 22:05 ` [PATCH 03/10] blkcg: separate blkcg_conf_get_disk() out of blkg_conf_prep() Tejun Heo
2019-08-28 22:05 ` [PATCH 04/10] block/rq_qos: add rq_qos_merge() Tejun Heo
2019-08-28 22:05 ` [PATCH 05/10] block/rq_qos: implement rq_qos_ops->queue_depth_changed() Tejun Heo
2019-08-28 22:05 ` [PATCH 06/10] blkcg: s/RQ_QOS_CGROUP/RQ_QOS_LATENCY/ Tejun Heo
2019-08-28 22:05 ` [PATCH 07/10] blk-mq: add optional request->alloc_time_ns Tejun Heo
2019-08-28 22:05 ` [PATCH 08/10] blkcg: implement blk-iocost Tejun Heo
2019-08-29 15:53   ` [PATCH] blkcg: fix missing free on error path of blk_iocost_init() Tejun Heo
2019-09-10 12:55   ` Michal Koutný [this message]
2019-09-10 16:08     ` [PATCH 08/10] blkcg: implement blk-iocost Tejun Heo
2019-09-11  8:18       ` Paolo Valente
2019-09-11 14:16         ` Tejun Heo
2019-09-11 15:54           ` Tejun Heo
2019-09-11 16:44           ` Paolo Valente
2019-10-03 14:51       ` Michal Koutný
2019-10-03 16:45         ` Tejun Heo
2019-10-09 15:36           ` Michal Koutný
2019-10-14 15:36             ` Tejun Heo
2019-11-01 16:15               ` Michal Koutný
2019-11-01 16:56                 ` Paolo Valente
2019-08-28 22:05 ` [PATCH 09/10] blkcg: add tools/cgroup/iocost_monitor.py Tejun Heo
2019-08-28 22:06 ` [PATCH 10/10] blkcg: add tools/cgroup/iocost_coef_gen.py Tejun Heo
2019-08-29  3:29 ` [PATCHSET v3 block/for-linus] IO cost model based work-conserving porportional controller Jens Axboe
     [not found] ` <20190829082248.6464-1-hdanton@sina.com>
2019-08-29 15:43   ` [PATCH 07/10] blk-mq: add optional request->alloc_time_ns Tejun Heo
     [not found] ` <20190829133928.16192-1-hdanton@sina.com>
2019-08-29 15:46   ` [PATCH 08/10] blkcg: implement blk-iocost Tejun Heo
2019-08-29 15:54 ` [PATCHSET v3 block/for-linus] IO cost model based work-conserving porportional controller Paolo Valente
2019-08-29 15:56   ` Tejun Heo
  -- strict thread matches above, loose matches on Subject: below --
2019-07-10 20:51 [PATCHSET v2 " Tejun Heo
2019-07-10 20:51 ` [PATCH 08/10] blkcg: implement blk-iocost Tejun Heo

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