Date:   Mon, 6 Feb 2023 16:00:05 +0100
From:   Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>
To:     Ofir Gal <ofir.gal@volumez.com>
Cc:     ming.lei@redhat.com, axboe@kernel.dk, cgroups@vger.kernel.org,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        tj@kernel.org, yi.zhang@huawei.com, yukuai3@huawei.com,
        Ofir Gal <ofir@gal.software>
Subject: Re: [PATCH -next] blk-throttle: enable io throttle for root in
 cgroup v2
Message-ID: <20230206150005.GA21332@blackbody.suse.cz>
References: <YgMxjyVjMjmkMQU5@T590>
 <20230205155541.1320485-1-ofir.gal@volumez.com>
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On Sun, Feb 05, 2023 at 05:55:41PM +0200, Ofir Gal <ofir.gal@volumez.com> w=
rote:
> I have tried to limit the SSD on Server #1, but it seems that the NVME
> target kworkers are not affected unless I use Yu Kuai's patch.
>=20
> Can you elaborate on the issues with this patch or how the scenario
> described above can be done with cgroups v2?

The issue is that if there's a client that doesn't implement
self-throttling you cannot guarantee anything on the server side.
Hence the mechanism must exist on the server side.

The NVME target should charge IO to respective blkcg's (just a generic
advice, I'm not familiar with that interface; see also
kthread_associate_blkcg() use in loop device driver).

HTH,
Michal

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