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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 6C5DDC433ED for ; Tue, 18 May 2021 12:55:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4AE00611CE for ; Tue, 18 May 2021 12:55:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349420AbhERM4Z (ORCPT ); Tue, 18 May 2021 08:56:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33454 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349401AbhERM4S (ORCPT ); Tue, 18 May 2021 08:56:18 -0400 Received: from mail-lj1-x229.google.com (mail-lj1-x229.google.com [IPv6:2a00:1450:4864:20::229]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6D9F3C06175F for ; Tue, 18 May 2021 05:54:59 -0700 (PDT) Received: by mail-lj1-x229.google.com with SMTP id e2so5105016ljk.4 for ; Tue, 18 May 2021 05:54:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uged.al; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=FHrO7R178ZgAEl57M73kYgQb5jhyv+gIfGWJWUwWLPc=; b=W3GL++BT3PKitCks3wvqU3a7V9CTSU83IAVCzWRBUQIkZO1oz9lQAtum11OWRhuZa5 8dIxNcx7bE4GyAYf/nCoIxt3nRyW1T71W7sT3t/7ViNYw0mGaegEnJJO7zGs7KUeRFuG bZtd0VdAKG6bUFG9LwJ5Jk7fJqXVOuDLgY8PAKnU+biM8HhgpiFDKIjqra+cO2mm47Ov JWF/nfansj2ksgn861WROFG6HrzeNhh8yoNNWPhmNmchqSixFEUH4OO/ssDO6v5/ZgEt vso/Fd05uD/5wxl1wOYbSOzKAni0/FMZhkv5pQ4Sfp8QFCflud+9rTAGvEbIR7RJYk92 SdHA== 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=FHrO7R178ZgAEl57M73kYgQb5jhyv+gIfGWJWUwWLPc=; b=OmGHduaQ8FkDpz7pilrcoXe/+5DEp93e3r6G1oIiOjT0pK8xmkxirPZfE9lTk6LMzh oyW5XcmXRMShJujS6nRM5tkKhdujEY2v9ZDNApAxxG5BD0oolXuXzI5TTHcC+VYt2WGC ubE0LEdGdXWyzB5tb9EQUwTHZ3YgzTvI9I/+mtHtaU5YEUx+H6IeEvDbEKEMsvh1n2RF BRaAFcWCqwR2myjV89C58SMcqKjQWFMMaYLIIgFp0H5HVVcobgBkh+lQPYM7+CF+Y3+0 QhKpKR3d7Ik2+UWwRyDo3gktTDMuLNiCA7gaRXVePZk/CFcd2mdXP0UHnTYsczZ1sgv/ cvEQ== X-Gm-Message-State: AOAM531/k3IbZSC5dZsspM2dtchm6vjhCjrhf8gTt7M3GGrzsl/kV9ga 7nEujahx7P0Ybgt7cPAuAAZRuQ== X-Google-Smtp-Source: ABdhPJxrQmPyCBnJBQIw+zDRDd2PshuShGr+0IhK6b84ELpkckV8GkPl+t9D7vUS/Yya4XS2ak+CCw== X-Received: by 2002:a2e:8e66:: with SMTP id t6mr3996220ljk.481.1621342497929; Tue, 18 May 2021 05:54:57 -0700 (PDT) Received: from localhost.localdomain (ti0005a400-2351.bb.online.no. [80.212.254.60]) by smtp.gmail.com with ESMTPSA id v14sm2265898lfb.201.2021.05.18.05.54.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 May 2021 05:54:57 -0700 (PDT) From: Odin Ugedal To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Odin Ugedal Subject: [PATCH 2/3] sched/fair: Correctly insert cfs_rq's to list on unthrottle Date: Tue, 18 May 2021 14:52:01 +0200 Message-Id: <20210518125202.78658-3-odin@uged.al> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210518125202.78658-1-odin@uged.al> References: <20210518125202.78658-1-odin@uged.al> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This fixes an issue where fairness is decreased since cfs_rq's can end up not being decayed properly. For two sibling control groups with the same priority, this can often lead to a load ratio of 99/1 (!!). This happen because when a cfs_rq is throttled, all the descendant cfs_rq's will be removed from the leaf list. When they initial cfs_rq is unthrottled, it will currently only re add descendant cfs_rq's if they have one or more entities enqueued. This is not a perfect heuristic. This fix change this behavior to save what cfs_rq's was removed from the list, and readds them properly on unthrottle. Can often lead to sutiations like this for equally weighted control groups: $ ps u -C stress USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 10009 88.8 0.0 3676 100 pts/1 R+ 11:04 0:13 stress --cpu 1 root 10023 3.0 0.0 3676 104 pts/1 R+ 11:04 0:00 stress --cpu 1 Fixes: 31bc6aeaab1d ("sched/fair: Optimize update_blocked_averages()") Signed-off-by: Odin Ugedal --- kernel/sched/fair.c | 11 ++++++----- kernel/sched/sched.h | 1 + 2 files changed, 7 insertions(+), 5 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ceda53c2a87a..e7423d658389 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -376,7 +376,8 @@ static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) return false; } -static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) +/* Returns 1 if cfs_rq was present in the list and removed */ +static inline bool list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) { if (cfs_rq->on_list) { struct rq *rq = rq_of(cfs_rq); @@ -393,7 +394,9 @@ static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) list_del_rcu(&cfs_rq->leaf_cfs_rq_list); cfs_rq->on_list = 0; + return 1; } + return 0; } static inline void assert_list_leaf_cfs_rq(struct rq *rq) @@ -4742,9 +4745,7 @@ static int tg_unthrottle_up(struct task_group *tg, void *data) if (!cfs_rq->throttle_count) { cfs_rq->throttled_clock_task_time += rq_clock_task(rq) - cfs_rq->throttled_clock_task; - - /* Add cfs_rq with already running entity in the list */ - if (cfs_rq->nr_running >= 1) + if (cfs_rq->insert_on_unthrottle) list_add_leaf_cfs_rq(cfs_rq); } @@ -4759,7 +4760,7 @@ static int tg_throttle_down(struct task_group *tg, void *data) /* group is entering throttled state, stop time */ if (!cfs_rq->throttle_count) { cfs_rq->throttled_clock_task = rq_clock_task(rq); - list_del_leaf_cfs_rq(cfs_rq); + cfs_rq->insert_on_unthrottle = list_del_leaf_cfs_rq(cfs_rq); } cfs_rq->throttle_count++; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index a189bec13729..12a707d99ee6 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -602,6 +602,7 @@ struct cfs_rq { u64 throttled_clock_task_time; int throttled; int throttle_count; + int insert_on_unthrottle; struct list_head throttled_list; #endif /* CONFIG_CFS_BANDWIDTH */ #endif /* CONFIG_FAIR_GROUP_SCHED */ -- 2.31.1 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Odin Ugedal Subject: [PATCH 2/3] sched/fair: Correctly insert cfs_rq's to list on unthrottle Date: Tue, 18 May 2021 14:52:01 +0200 Message-ID: <20210518125202.78658-3-odin@uged.al> References: <20210518125202.78658-1-odin@uged.al> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=uged.al; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=FHrO7R178ZgAEl57M73kYgQb5jhyv+gIfGWJWUwWLPc=; b=W3GL++BT3PKitCks3wvqU3a7V9CTSU83IAVCzWRBUQIkZO1oz9lQAtum11OWRhuZa5 8dIxNcx7bE4GyAYf/nCoIxt3nRyW1T71W7sT3t/7ViNYw0mGaegEnJJO7zGs7KUeRFuG bZtd0VdAKG6bUFG9LwJ5Jk7fJqXVOuDLgY8PAKnU+biM8HhgpiFDKIjqra+cO2mm47Ov JWF/nfansj2ksgn861WROFG6HrzeNhh8yoNNWPhmNmchqSixFEUH4OO/ssDO6v5/ZgEt vso/Fd05uD/5wxl1wOYbSOzKAni0/FMZhkv5pQ4Sfp8QFCflud+9rTAGvEbIR7RJYk92 SdHA== In-Reply-To: <20210518125202.78658-1-odin-RObV4cXtwVA@public.gmane.org> List-ID: Content-Type: text/plain; charset="us-ascii" To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Odin Ugedal This fixes an issue where fairness is decreased since cfs_rq's can end up not being decayed properly. For two sibling control groups with the same priority, this can often lead to a load ratio of 99/1 (!!). This happen because when a cfs_rq is throttled, all the descendant cfs_rq's will be removed from the leaf list. When they initial cfs_rq is unthrottled, it will currently only re add descendant cfs_rq's if they have one or more entities enqueued. This is not a perfect heuristic. This fix change this behavior to save what cfs_rq's was removed from the list, and readds them properly on unthrottle. Can often lead to sutiations like this for equally weighted control groups: $ ps u -C stress USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 10009 88.8 0.0 3676 100 pts/1 R+ 11:04 0:13 stress --cpu 1 root 10023 3.0 0.0 3676 104 pts/1 R+ 11:04 0:00 stress --cpu 1 Fixes: 31bc6aeaab1d ("sched/fair: Optimize update_blocked_averages()") Signed-off-by: Odin Ugedal --- kernel/sched/fair.c | 11 ++++++----- kernel/sched/sched.h | 1 + 2 files changed, 7 insertions(+), 5 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ceda53c2a87a..e7423d658389 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -376,7 +376,8 @@ static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) return false; } -static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) +/* Returns 1 if cfs_rq was present in the list and removed */ +static inline bool list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) { if (cfs_rq->on_list) { struct rq *rq = rq_of(cfs_rq); @@ -393,7 +394,9 @@ static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) list_del_rcu(&cfs_rq->leaf_cfs_rq_list); cfs_rq->on_list = 0; + return 1; } + return 0; } static inline void assert_list_leaf_cfs_rq(struct rq *rq) @@ -4742,9 +4745,7 @@ static int tg_unthrottle_up(struct task_group *tg, void *data) if (!cfs_rq->throttle_count) { cfs_rq->throttled_clock_task_time += rq_clock_task(rq) - cfs_rq->throttled_clock_task; - - /* Add cfs_rq with already running entity in the list */ - if (cfs_rq->nr_running >= 1) + if (cfs_rq->insert_on_unthrottle) list_add_leaf_cfs_rq(cfs_rq); } @@ -4759,7 +4760,7 @@ static int tg_throttle_down(struct task_group *tg, void *data) /* group is entering throttled state, stop time */ if (!cfs_rq->throttle_count) { cfs_rq->throttled_clock_task = rq_clock_task(rq); - list_del_leaf_cfs_rq(cfs_rq); + cfs_rq->insert_on_unthrottle = list_del_leaf_cfs_rq(cfs_rq); } cfs_rq->throttle_count++; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index a189bec13729..12a707d99ee6 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -602,6 +602,7 @@ struct cfs_rq { u64 throttled_clock_task_time; int throttled; int throttle_count; + int insert_on_unthrottle; struct list_head throttled_list; #endif /* CONFIG_CFS_BANDWIDTH */ #endif /* CONFIG_FAIR_GROUP_SCHED */ -- 2.31.1