From: Jens Axboe <axboe@kernel.dk>
To: Paolo Valente <paolo.valente@linaro.org>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
ulf.hansson@linaro.org, linus.walleij@linaro.org,
broonie@kernel.org, bfq-iosched@googlegroups.com,
oleksandr@natalenko.name
Subject: Re: [PATCH 0/2] block, bfq: add weight symlink to the bfq.weight cgroup parameter
Date: Fri, 7 Jun 2019 01:30:10 -0600 [thread overview]
Message-ID: <854dd83a-bd07-c1c3-d005-ef7a62f0fa35@kernel.dk> (raw)
In-Reply-To: <20190521080155.36178-1-paolo.valente@linaro.org>
On 5/21/19 2:01 AM, Paolo Valente wrote:
> Many userspace tools and services use the proportional-share policy of
> the blkio/io cgroups controller. The CFQ I/O scheduler implemented
> this policy for the legacy block layer. To modify the weight of a
> group in case CFQ was in charge, the 'weight' parameter of the group
> must be modified. On the other hand, the BFQ I/O scheduler implements
> the same policy in blk-mq, but, with BFQ, the parameter to modify has
> a different name: bfq.weight (forced choice until legacy block was
> present, because two different policies cannot share a common parameter
> in cgroups).
>
> Due to CFQ legacy, most if not all userspace configurations still use
> the parameter 'weight', and for the moment do not seem likely to be
> changed. But, when CFQ went away with legacy block, such a parameter
> ceased to exist.
>
> So, a simple workaround has been proposed by Johannes [1] to make all
> configurations work: add a symlink, named weight, to bfq.weight. This
> pair of patches adds:
> 1) the possibility to create a symlink to a cgroup file;
> 2) the above 'weight' symlink.
Applied, thanks.
--
Jens Axboe
prev parent reply other threads:[~2019-06-07 7:30 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-21 8:01 [PATCH 0/2] block, bfq: add weight symlink to the bfq.weight cgroup parameter Paolo Valente
2019-05-21 8:01 ` [PATCH 1/2] cgroup: let a symlink too be created with a cftype file Paolo Valente
2019-05-21 8:01 ` [PATCH 2/2] block, bfq: add weight symlink to the bfq.weight cgroup parameter Paolo Valente
2019-05-30 15:02 ` [PATCH 0/2] " Paolo Valente
2019-06-07 6:20 ` Paolo Valente
2019-06-07 7:30 ` Jens Axboe [this message]
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