From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 425BFC04AAF for ; Tue, 21 May 2019 08:02:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 16BEF217D4 for ; Tue, 21 May 2019 08:02:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="U5lZgDhD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727202AbfEUICm (ORCPT ); Tue, 21 May 2019 04:02:42 -0400 Received: from mail-wm1-f68.google.com ([209.85.128.68]:37757 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725790AbfEUICl (ORCPT ); Tue, 21 May 2019 04:02:41 -0400 Received: by mail-wm1-f68.google.com with SMTP id 7so1814644wmo.2 for ; Tue, 21 May 2019 01:02:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=DOhhDvGFx5TQBrV3vUuuJNqU81qFULp2qAUcY70tdpo=; b=U5lZgDhD03GpNQCNQxmESbv9lWfJZcDrizZYolBCQqWW/xEYt9UwLILokyg8eZw2fv OoHDixUXEs4MfaUj9VCaYKeLQ6CgxSEf+3dN3WetIPP+SUCRY7n1qJjhUO9i7So752mT eOVjY3sdJA+kTXkPvE52Mc0lf6Qz9kuRXbijZTvxFeFXk/rtACX7jccmZp1RgxGZpYNb R8icSFl8ioKe7x+3GqeaG1+kGo2RQ5tP0EH7tAtsrz9RlLQT0gbcEiXM0C89oq41RMxJ 131Ipwk/vsUv5tD+3ALHha2SVRHMkreikP5BaMJXOjM6YlJ28mWz/Gj0x3kuklYPyrNb hU3A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=DOhhDvGFx5TQBrV3vUuuJNqU81qFULp2qAUcY70tdpo=; b=S42pJUsomWjoyrb/lT99yelXxzToVMyCVp8ltymNV/xzNQ29g5uI413lWlvuOaXwOa f5/DdEJHBphncIyfS12fhN9ebYNdUPjL8dw6YSuZAa3t2O5OwdvB/0I2NyQit7m/H89S w61v95ocXsustgPQI/gc6OG62MnMlE75bYWvKVCLMGLR6edyGf7336aokAlr2JMSylB7 SB3lokYr+U4H2bzg1ThETco3O71kD+Xzq+oZznwS/EG2yPKmziikvKu+3pS45IFqqoHo GuTOlDBg8WQ+2YkmveIl4poEF7LTjKtklW9/Q9+qYjQz+6WzhZTlUr3kge2rMN4G3xTn Iimw== X-Gm-Message-State: APjAAAVjM1iisAR+36YdcPUzOOiuEfylCTAD6K39hcrKDf/XKjEmc9l3 qn6z4+7lZ3GV/RIPFcv8fyRHZw== X-Google-Smtp-Source: APXvYqyspoPg9SEqm8OAK4EKMduyZ0wkoaz46tnzvrFz0D5YKN4kzgcvCqAOYUkBdjzY7BugddgXkw== X-Received: by 2002:a1c:3287:: with SMTP id y129mr2330502wmy.153.1558425759355; Tue, 21 May 2019 01:02:39 -0700 (PDT) Received: from localhost.localdomain ([88.147.35.136]) by smtp.gmail.com with ESMTPSA id p8sm11322301wro.0.2019.05.21.01.02.35 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 21 May 2019 01:02:38 -0700 (PDT) From: Paolo Valente To: Jens Axboe 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, Angelo Ruocco , Johannes Thumshirn , Paolo Valente Subject: [PATCH 2/2] block, bfq: add weight symlink to the bfq.weight cgroup parameter Date: Tue, 21 May 2019 10:01:55 +0200 Message-Id: <20190521080155.36178-3-paolo.valente@linaro.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190521080155.36178-1-paolo.valente@linaro.org> References: <20190521080155.36178-1-paolo.valente@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Angelo Ruocco 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 [1] to make all configurations work: add a symlink, named weight, to bfq.weight. This commit adds such a symlink. [1] https://lkml.org/lkml/2019/4/8/555 Suggested-by: Johannes Thumshirn Signed-off-by: Angelo Ruocco Signed-off-by: Paolo Valente --- block/bfq-cgroup.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index b3796a40a61a..59f46904cb11 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -1046,7 +1046,8 @@ struct blkcg_policy blkcg_policy_bfq = { struct cftype bfq_blkcg_legacy_files[] = { { .name = "bfq.weight", - .flags = CFTYPE_NOT_ON_ROOT, + .link_name = "weight", + .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_SYMLINKED, .seq_show = bfq_io_show_weight, .write_u64 = bfq_io_set_weight_legacy, }, @@ -1166,7 +1167,8 @@ struct cftype bfq_blkcg_legacy_files[] = { struct cftype bfq_blkg_files[] = { { .name = "bfq.weight", - .flags = CFTYPE_NOT_ON_ROOT, + .link_name = "weight", + .flags = CFTYPE_NOT_ON_ROOT | CFTYPE_SYMLINKED, .seq_show = bfq_io_show_weight, .write = bfq_io_set_weight, }, -- 2.20.1