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[88.147.34.172]) by smtp.gmail.com with ESMTPSA id n7sm804018wrw.64.2019.06.06.23.20.22 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Jun 2019 23:20:22 -0700 (PDT) From: Paolo Valente Message-Id: <38971C09-E691-4129-BE6A-E21337EAE884@linaro.org> Content-Type: multipart/signed; boundary="Apple-Mail=_7DA8BBC8-3D3F-41ED-B7DD-4265FA89D2CE"; protocol="application/pgp-signature"; micalg=pgp-sha256 Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.8\)) Subject: Re: [PATCH 0/2] block, bfq: add weight symlink to the bfq.weight cgroup parameter Date: Fri, 7 Jun 2019 08:20:21 +0200 In-Reply-To: <406CC451-A318-4EC5-942D-4CCFABFBC402@linaro.org> Cc: linux-block , kernel list , Ulf Hansson , Linus Walleij , Mark Brown , noreply-spamdigest via bfq-iosched , Oleksandr Natalenko , Angelo Ruocco , Fam Zheng To: Jens Axboe References: <20190521080155.36178-1-paolo.valente@linaro.org> <406CC451-A318-4EC5-942D-4CCFABFBC402@linaro.org> X-Mailer: Apple Mail (2.3445.104.8) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org --Apple-Mail=_7DA8BBC8-3D3F-41ED-B7DD-4265FA89D2CE Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii ping > Il giorno 30 mag 2019, alle ore 17:02, Paolo Valente = ha scritto: >=20 > Hi Jens, > have you had time to look into this? >=20 > Thanks, > Paolo >=20 >> Il giorno 21 mag 2019, alle ore 10:01, Paolo Valente = ha scritto: >>=20 >> 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). >>=20 >> 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. >>=20 >> 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. >>=20 >> Thanks, >> Paolo >>=20 >> [1] https://lkml.org/lkml/2019/4/8/555 >>=20 >> Angelo Ruocco (2): >> cgroup: let a symlink too be created with a cftype file >> block, bfq: add weight symlink to the bfq.weight cgroup parameter >>=20 >> block/bfq-cgroup.c | 6 ++++-- >> include/linux/cgroup-defs.h | 3 +++ >> kernel/cgroup/cgroup.c | 33 +++++++++++++++++++++++++++++---- >> 3 files changed, 36 insertions(+), 6 deletions(-) >>=20 >> -- >> 2.20.1 >=20 --Apple-Mail=_7DA8BBC8-3D3F-41ED-B7DD-4265FA89D2CE Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEpYoduex+OneZyvO8OAkCLQGo9oMFAlz6AiUACgkQOAkCLQGo 9oNu6Q/9Hkd8DyVaH7dQ59vEgRtqcgg1iU6GP+VNGUTxNLZ09Ods6bqmZrcGke9K phBaiKyrkzh3ozmIpgZItaVcQ7XcIQjt7c22ZzEZyXHb9WB3LSDePOyM+rwpG0qX PlHlzjU8IZuOmzYrFJcwblxFsbMD0+Qsje0/d43nEbRd6UP49woSROPDgzYdFGJM YctiEH9StBuyWze/jjTiUqffRRsHgacfLIlnGX9hy0vtzQgwK72RnVNbqsMDQvUA /fZapznTAQ65g5PbdhMd9EngLNmHUQecbcZL2f/CFMWeA0J3DsEJfdTi6rA2dD9T EgMSRlRAOzt7ruMtN7S9pWaVVQr6SyymNmnEMwhe5X6Lg4v+W65762g8A7aAIKDa EiNMQ6tSquvY8k1CO4NSRGkeyyHgsyLHxL0GRTenbkCIxkf8aNOLStetIIbh3q33 aDGWVUPzaEawo0BLCJbafoBDm/JXfIElNZfY9Hk73Xq+UghIjUSAwmeHxtei4t6k iLKItx4eU7CLY5l82JAYNBz6Q+h8ZtX6FsAZjT6XJ8Y0cWo8t8bpZ+HDxsh8TVRX txH+gujqQ6lH3arNmGFrZsUhbDUrRzMsAABbOyS3hsT5dqWvoeWYIi12+C6imK91 OkTgvztoDswDelvgkTbbZ/ZmkniTpIR6lerb1EbLZ1ot3Un8A64= =A1RR -----END PGP SIGNATURE----- --Apple-Mail=_7DA8BBC8-3D3F-41ED-B7DD-4265FA89D2CE--