From patchwork Thu Mar 25 06:57:50 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "brookxu.cn" X-Patchwork-Id: 12163167 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 949AEC433E3 for ; Thu, 25 Mar 2021 06:58:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6D54761A2D for ; Thu, 25 Mar 2021 06:58:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229888AbhCYG6T (ORCPT ); Thu, 25 Mar 2021 02:58:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37696 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229669AbhCYG6M (ORCPT ); Thu, 25 Mar 2021 02:58:12 -0400 Received: from mail-pf1-x42f.google.com (mail-pf1-x42f.google.com [IPv6:2607:f8b0:4864:20::42f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D961DC06174A; Wed, 24 Mar 2021 23:58:11 -0700 (PDT) Received: by mail-pf1-x42f.google.com with SMTP id l123so1046754pfl.8; Wed, 24 Mar 2021 23:58:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :in-reply-to:references; bh=bSZL7kirn3ytucnGGJSGBi1K6j7tN0mB+xwGax7QE0Y=; b=cmCca1wwq8zjRNpdjae2qHgjfPHbVBjdywuM1tOtPlKfMmzaZnxQ6e3GVwbKNJKaVT Up55cWUaqfRohYZpnnlbJbT3JLf4zHGk56fPXxhCmyS3TJARXxFLeyInbRH0oQWftz2+ 2q8tZg/mGjCTy7PlPRPJxGWMIm7468fkAZzq3yRDy2vBZJVcvbiLkYJncyF4WC4DXBv/ MwNXuSlodHn9mqrCmRmzFnJyblv6HMM6TSXx5a2WlXn1eYZQERxNEg2YLpsTSzxJzsJA TqWVPe7cYuJG81gU4BGDXafywDXxaxFKHaTm/jwkKa8Pa+vCtnl2yLlw+KneN1vaz86L EARg== 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:in-reply-to:references; bh=bSZL7kirn3ytucnGGJSGBi1K6j7tN0mB+xwGax7QE0Y=; b=aDSi4ePrudvQMQ1YzLdl09h7aVjXDGaKbmUDodNQSdLCArssw5LCF3wFPXgltc05cd OFuvg4lxXITXAZICmObQ2TgLjRKNh1U/wbvyItc2iQ5agJG9YTJsg50gcvviwht0blHh 8BxWnmq0Q0mca8C/at+FnoQAwSTJwI9/J/pUNDjFpuVALJbo/RpxOIme8Tlt7GtrpNic J+z8yw5h/mOwg3Fu9VLjcbGfBovFHpp8JJtwNkijlv2VZ6sWN+tgVeMrptbgiR/P7sr3 FRuEP/j6j6TrTPPF278N8+Udiz7nVvFZ70uGc3jzvfHKycysWr57keiMw30NM1Wn4hmF GHJg== X-Gm-Message-State: AOAM532kg8LhpjVOSPb9mb572kECQg+guk77K2KHOcKt/WKpgd+VKhAE 3T8QMfDpbaVDdL+/+TJHFjI= X-Google-Smtp-Source: ABdhPJw71CEG0gy51mM9pTZzYjxnfd2Vl4qBqVb6NIJJ1S7/DSsFwUbv+8uGU1ND2Rh5YuUgZNrJpw== X-Received: by 2002:a17:902:7886:b029:e7:1052:adad with SMTP id q6-20020a1709027886b02900e71052adadmr6950740pll.75.1616655491471; Wed, 24 Mar 2021 23:58:11 -0700 (PDT) Received: from VM-0-3-centos.localdomain ([101.32.213.191]) by smtp.gmail.com with ESMTPSA id x19sm4470202pfc.152.2021.03.24.23.58.09 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 24 Mar 2021 23:58:11 -0700 (PDT) From: brookxu To: paolo.valente@linaro.org, axboe@kernel.dk, tj@kernel.org Cc: linux-block@vger.kernel.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 06/14] bfq: keep the minimun bandwidth for CLASS_BE Date: Thu, 25 Mar 2021 14:57:50 +0800 Message-Id: X-Mailer: git-send-email 1.8.3.1 In-Reply-To: References: In-Reply-To: References: Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Chunguang Xu CLASS_RT will preempt other classes, which may starve. At present, CLASS_IDLE has alleviated the starvation problem through the minimum bandwidth mechanism. Similarly, we should do the same for CLASS_BE. Signed-off-by: Chunguang Xu --- block/bfq-iosched.c | 6 ++++-- block/bfq-iosched.h | 11 ++++++---- block/bfq-wf2q.c | 59 ++++++++++++++++++++++++++++++++++++++--------------- 3 files changed, 53 insertions(+), 23 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 8eaf0eb..ee8c457 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -6560,9 +6560,11 @@ static void bfq_init_root_group(struct bfq_group *root_group, root_group->bfqd = bfqd; #endif root_group->rq_pos_tree = RB_ROOT; - for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) + for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) { root_group->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; - root_group->sched_data.bfq_class_idle_last_service = jiffies; + root_group->sched_data.bfq_class_last_service[i] = jiffies; + } + root_group->sched_data.class_timeout_last_check = jiffies; } static int bfq_init_queue(struct request_queue *q, struct elevator_type *e) diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h index 29a56b8..f9ed1da 100644 --- a/block/bfq-iosched.h +++ b/block/bfq-iosched.h @@ -13,7 +13,7 @@ #include "blk-cgroup-rwstat.h" #define BFQ_IOPRIO_CLASSES 3 -#define BFQ_CL_IDLE_TIMEOUT (HZ/5) +#define BFQ_CLASS_TIMEOUT (HZ/5) #define BFQ_MIN_WEIGHT 1 #define BFQ_MAX_WEIGHT 1000 @@ -97,9 +97,12 @@ struct bfq_sched_data { struct bfq_entity *next_in_service; /* array of service trees, one per ioprio_class */ struct bfq_service_tree service_tree[BFQ_IOPRIO_CLASSES]; - /* last time CLASS_IDLE was served */ - unsigned long bfq_class_idle_last_service; - + /* last time the class was served */ + unsigned long bfq_class_last_service[BFQ_IOPRIO_CLASSES]; + /* last time class timeout was checked */ + unsigned long class_timeout_last_check; + /* next index to check class timeout */ + unsigned int next_class_index; }; /** diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c index c91109e..1f8f3c5 100644 --- a/block/bfq-wf2q.c +++ b/block/bfq-wf2q.c @@ -1188,6 +1188,7 @@ bool __bfq_deactivate_entity(struct bfq_entity *entity, bool ins_into_idle_tree) { struct bfq_sched_data *sd = entity->sched_data; struct bfq_service_tree *st; + int idx = bfq_class_idx(entity); bool is_in_service; if (!entity->on_st_or_in_serv) /* @@ -1227,6 +1228,7 @@ bool __bfq_deactivate_entity(struct bfq_entity *entity, bool ins_into_idle_tree) else bfq_idle_insert(st, entity); + sd->bfq_class_last_service[idx] = jiffies; return true; } @@ -1455,6 +1457,45 @@ static struct bfq_entity *bfq_first_active_entity(struct bfq_service_tree *st, return entity; } +static int bfq_select_next_class(struct bfq_sched_data *sd) +{ + struct bfq_service_tree *st = sd->service_tree; + unsigned long last_check, last_serve; + int i, class_idx, next_class = 0; + bool found = false; + + /* + * we needed to guarantee a minimum bandwidth for each class (if + * there is some active entity in this class). This should also + * mitigate priority-inversion problems in case a low priority + * task is holding file system resources. + */ + last_check = sd->class_timeout_last_check; + if (time_is_after_jiffies(last_check + BFQ_CLASS_TIMEOUT)) + return next_class; + + sd->class_timeout_last_check = jiffies; + for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) { + class_idx = (sd->next_class_index + i) % BFQ_IOPRIO_CLASSES; + last_serve = sd->bfq_class_last_service[class_idx]; + + if (time_is_after_jiffies(last_serve + BFQ_CLASS_TIMEOUT)) + continue; + + if (!RB_EMPTY_ROOT(&(st + class_idx)->active)) { + if (found) + continue; + + next_class = class_idx++; + class_idx %= BFQ_IOPRIO_CLASSES; + sd->next_class_index = class_idx; + found = true; + } + sd->bfq_class_last_service[class_idx] = jiffies; + } + return next_class; +} + /** * bfq_lookup_next_entity - return the first eligible entity in @sd. * @sd: the sched_data. @@ -1468,24 +1509,8 @@ static struct bfq_entity *bfq_lookup_next_entity(struct bfq_sched_data *sd, bool expiration) { struct bfq_service_tree *st = sd->service_tree; - struct bfq_service_tree *idle_class_st = st + (BFQ_IOPRIO_CLASSES - 1); struct bfq_entity *entity = NULL; - int class_idx = 0; - - /* - * Choose from idle class, if needed to guarantee a minimum - * bandwidth to this class (and if there is some active entity - * in idle class). This should also mitigate - * priority-inversion problems in case a low priority task is - * holding file system resources. - */ - if (time_is_before_jiffies(sd->bfq_class_idle_last_service + - BFQ_CL_IDLE_TIMEOUT)) { - if (!RB_EMPTY_ROOT(&idle_class_st->active)) - class_idx = BFQ_IOPRIO_CLASSES - 1; - /* About to be served if backlogged, or not yet backlogged */ - sd->bfq_class_idle_last_service = jiffies; - } + int class_idx = bfq_select_next_class(sd); /* * Find the next entity to serve for the highest-priority