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intel_pstate_update_util+0x3b0/0x3b0 rq_offline_rt+0x1b7/0x250 set_rq_offline.part.120+0x28/0x60 rq_attach_root+0xc4/0xd0 cpu_attach_domain+0x3dc/0x7f0 ? __schedule+0x65e/0x1310 partition_sched_domains_locked+0x2a5/0x3c0 rebuild_sched_domains_locked+0x477/0x830 ? percpu_rwsem_wait+0x140/0x140 rebuild_sched_domains+0x1b/0x30 cpuset_hotplug_workfn+0x2ca/0xc90 ? balance_push+0x56/0x120 ? _raw_spin_unlock+0x15/0x30 ? finish_task_switch+0x98/0x2f0 ? __switch_to+0x116/0x410 ? __schedule+0x65e/0x1310 ? internal_add_timer+0x42/0x60 ? _raw_spin_unlock_irqrestore+0x23/0x40 ? add_timer_on+0xd5/0x130 process_one_work+0x1bc/0x3d0 worker_thread+0x4c/0x380 ? preempt_count_add+0x56/0xa0 ? rescuer_thread+0x310/0x310 kthread+0xe6/0x110 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x1f/0x30 More detailed key function call graph: rq_offline_rt() __disable_runtime() sched_rt_rq_enqueue() enqueue_top_rt_rq() cpufreq_update_util() <-- depends on CONFIG_CPU_FREQ data->func(data, *rq_clock(rq)*, flags) intel_pstate_update_util() <-- powersave policy callback function Before calling rq_offline_rt() we need to update the rq clock to avoid using the old rq clock, So we add update_rq_clock() to set_rq_offline() to update rq clock. And we use rq_lock_irqsave()/rq_unlock_irqrestore() to replace raw_spin_rq_lock_irqsave()/raw_spin_rq_unlock_irqrestore() in rq_attach_root() to ensure that rq->clock_update_flags are cleared before updating the rq clock. Steps to reproduce: 1. Enable CONFIG_SMP and CONFIG_CPU_FREQ when compiling the kernel 2. echo 1 > /sys/kernel/debug/clear_warn_once 3. cpupower -c all frequency-set -g powersave 4. Run some rt tasks e.g. Create 5*n rt (100% running) tasks (on a system with n CPUs) 5. Offline cpu one by one until the warninng is triggered Suggested-by: Ben Segall Signed-off-by: Hao Jia Reviewed-by: Vincent Guittot --- kernel/sched/core.c | 2 +- kernel/sched/topology.c | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index a68d1276bab0..a8be5415daba 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -9548,6 +9548,7 @@ void set_rq_offline(struct rq *rq) if (rq->online) { const struct sched_class *class; + update_rq_clock(rq); for_each_class(class) { if (class->rq_offline) class->rq_offline(rq); @@ -9689,7 +9690,6 @@ int sched_cpu_deactivate(unsigned int cpu) rq_lock_irqsave(rq, &rf); if (rq->rd) { - update_rq_clock(rq); BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span)); set_rq_offline(rq); } diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 6682535e37c8..52976eadfee9 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -487,9 +487,9 @@ static void free_rootdomain(struct rcu_head *rcu) void rq_attach_root(struct rq *rq, struct root_domain *rd) { struct root_domain *old_rd = NULL; - unsigned long flags; + struct rq_flags rf; - raw_spin_rq_lock_irqsave(rq, flags); + rq_lock_irqsave(rq, &rf); if (rq->rd) { old_rd = rq->rd; @@ -515,7 +515,7 @@ void rq_attach_root(struct rq *rq, struct root_domain *rd) if (cpumask_test_cpu(rq->cpu, cpu_active_mask)) set_rq_online(rq); - raw_spin_rq_unlock_irqrestore(rq, flags); + rq_unlock_irqrestore(rq, &rf); if (old_rd) call_rcu(&old_rd->rcu, free_rootdomain); From patchwork Tue Jun 13 08:20:10 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hao Jia X-Patchwork-Id: 107199 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:994d:0:b0:3d9:f83d:47d9 with SMTP id k13csp396425vqr; Tue, 13 Jun 2023 01:56:20 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ6M44iL7OTzqO5n+haVIjbCcpVgdH0qSt9RIdggY1S/uipbuvD3TZ4+oL+a1Lev6H96eRqH X-Received: by 2002:a2e:998a:0:b0:2ac:75fa:495c with SMTP id w10-20020a2e998a000000b002ac75fa495cmr4050072lji.27.1686646579674; Tue, 13 Jun 2023 01:56:19 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1686646579; cv=none; d=google.com; s=arc-20160816; b=AAW4T2aaKxPjOD+iSkVQJHttwbPnZb4MKK0HZKUopHiEek4lWKkp1xV7lOQz0G7/LN dqJVHrrZGUHIG0orubydLvOMN8uJtn9ak8Wss0iPnXrQh45YVGltA152+gzRQcQEIIGr O/a29zQIPMcVx9OC+C9M1zqG02qGM+S8DU+Iy8lHhKv4ubtt27pfA1RbqT4dYJnERQAp 3mU6oGy6K7KrP2lIzct+oJpoDsHCQiPrOtvYl0ShVYExWbLsEvNfRonKwdtEf2K4yMnM yVSuzlHQlqCgB/9a5RtRwvXgKZa2nBN18plufn88OZH93aSs4JKK6LwsoPUGOsrHo1Kz e0jA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=mnMCJfZwdw2Doj0IUCtluopHvDDUTBGrdKXsgPSQqls=; b=OpwiE2mNZFw/4I7oVWedVrgSUEAgQqyUuqW9A+jtLIgZy9RSGg035rjpmo0jBcURBu eOOe/zNkUKRgmzbG1HY/l5sPSXR2awyhb5+gi8dYigB8kEEyia/4lywpegihr+09xAf7 NYZ3s1uqMRomKeYSe5j+Cic27gdqD45FfDSLsqF16QdvywyhuKd5U2lVQMVC1fn+i1tC 6J9oRb4rj43DRyy72b8jXHIB1Cb2T61sF/kzIJQPCrdO2Ooo0c60K2txCyykpyKa4v0k Ia+YorA5Zx4ezIfgAZC+3n9PWuiPUWEbYRMZdNxu9rteIDG3H7ofzEhV8uUQ3DWl6Gtf MnFQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@bytedance.com header.s=google header.b="UF/uDbVJ"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=bytedance.com Received: from out1.vger.email (out1.vger.email. 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migration_cpu_stop+0x2a0/0x2a0 cpu_stopper_thread+0xa3/0x140 smpboot_thread_fn+0x14f/0x210 ? sort_range+0x20/0x20 kthread+0xe6/0x110 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x1f/0x30 To avoid this warning, we remove update_rq_clock() from the __migrate_task() function. And in order to avoid missing rq clock update, add update_rq_clock() call before migration_cpu_stop() calls __migrate_task(). Signed-off-by: Hao Jia Reviewed-by: Vincent Guittot --- kernel/sched/core.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index a8be5415daba..1eca36299d8b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2398,7 +2398,6 @@ static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf, if (!is_cpu_allowed(p, dest_cpu)) return rq; - update_rq_clock(rq); rq = move_queued_task(rq, rf, p, dest_cpu); return rq; @@ -2456,10 +2455,12 @@ static int migration_cpu_stop(void *data) goto out; } - if (task_on_rq_queued(p)) + if (task_on_rq_queued(p)) { + update_rq_clock(rq); rq = __migrate_task(rq, &rf, p, arg->dest_cpu); - else + } else { p->wake_cpu = arg->dest_cpu; + } /* * XXX __migrate_task() can fail, at which point we might end From patchwork Tue Jun 13 08:20:11 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hao Jia X-Patchwork-Id: 107201 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:994d:0:b0:3d9:f83d:47d9 with SMTP id k13csp396760vqr; Tue, 13 Jun 2023 01:57:18 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ6x0NT4bmMm14wHDHLPvI+l79v+qQesUajKb6f6D13VWpzX3DMb7G+FIGkfYinnjsSSWpfj X-Received: by 2002:a17:907:8a17:b0:94e:4b26:233c with SMTP id sc23-20020a1709078a1700b0094e4b26233cmr11254240ejc.16.1686646638225; Tue, 13 Jun 2023 01:57:18 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1686646638; cv=none; d=google.com; s=arc-20160816; b=Ayu/IsELKBq6AjdyihlGg0xZF/ucAF0wuDyg3r5IddzC7Ip0m+bP2fEL038f5k0ftQ DbxT87grT7hpH+J7iXG80AdK/+JEz7HR9dCpIr+GaOgHf9m6I6QJKtnkyfFi04AXbKka 3R68Mh/n9IoX/qvc9D+qKRTC7HOAvHoPRyqOEP6AF17Mion0gx1Yugnuwx/sr3JiIssO I9b5FCqJCo5AEMJARUuJzTGyre2Q1HB2w4/n1CKsiy8M1WDTMNPz1s39mjTPso8uKD/z 1A1RNozdLYB0QHWLU2eudtBJT/EzNvWOmEU+7uaPBn5DGbvUVALt1CiM8QLQU6PrKzlm NdsA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=NdXaw5dg9b8aDwiY+1vzb/StC7BleYDvDIrkoD6JVyU=; b=cJEBbqx0RJjWCjEnfBmp8rk/fBZQaqYHuCjyWBlxm3vBTiAcY9D3GdJG+ybbkgMx+p vGSekznmtH/xW5C8CRozy2ZIaA90Vd3//+YpBHWcPXgtzBah11ocubiK4fbuwTuTjF/0 J5y2z8vVwNEaqPOlvU61BunSthIgEEmEn3LAR5ak7RAjlnobHqPG7PbyR94z4/1ScF3i HUSP0kK6WrK/dVoB0LRXVMjWz+3yqxSJyK2JDjTqr1fTc8dQjjqQzXyD9b7oauHuazZv fD58Tb7UAecp7VxxApKeDuY3jTm++cX758W9Qk+Jz2QameOqVWL0xS+VTfJ3hnVHvqZw +Z/A== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@bytedance.com header.s=google header.b=MwkwZQfZ; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=bytedance.com Received: from out1.vger.email (out1.vger.email. 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At that time the following warning will be triggered. ------------[ cut here ]------------ rq->clock_update_flags & RQCF_UPDATED WARNING: CPU: 54 PID: 0 at kernel/sched/core.c:741 update_rq_clock+0xaf/0x180 Call Trace: unthrottle_cfs_rq+0x4b/0x300 __cfsb_csd_unthrottle+0xe0/0x100 __flush_smp_call_function_queue+0xaf/0x1d0 flush_smp_call_function_queue+0x49/0x90 do_idle+0x17c/0x270 cpu_startup_entry+0x19/0x20 start_secondary+0xfa/0x120 secondary_startup_64_no_verify+0xce/0xdb Before the loop starts, we update the rq clock once and call rq_clock_start_loop_update() to prevent updating the rq clock multiple times. And call rq_clock_stop_loop_update() After the loop to clear rq->clock_update_flags. Fixes: 8ad075c2eb1f ("sched: Async unthrottling for cfs bandwidth") Suggested-by: Vincent Guittot Signed-off-by: Hao Jia Reviewed-by: Vincent Guittot --- kernel/sched/fair.c | 9 +++++++++ kernel/sched/sched.h | 21 +++++++++++++++++++++ 2 files changed, 30 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 373ff5f55884..af9604f4b135 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5576,6 +5576,14 @@ static void __cfsb_csd_unthrottle(void *arg) rq_lock(rq, &rf); + /* + * Iterating over the list can trigger several call to + * update_rq_clock() in unthrottle_cfs_rq(). + * Do it once and skip the potential next ones. + */ + update_rq_clock(rq); + rq_clock_start_loop_update(rq); + /* * Since we hold rq lock we're safe from concurrent manipulation of * the CSD list. However, this RCU critical section annotates the @@ -5595,6 +5603,7 @@ static void __cfsb_csd_unthrottle(void *arg) rcu_read_unlock(); + rq_clock_stop_loop_update(rq); rq_unlock(rq, &rf); } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index ec7b3e0a2b20..50446e401b9f 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1546,6 +1546,27 @@ static inline void rq_clock_cancel_skipupdate(struct rq *rq) rq->clock_update_flags &= ~RQCF_REQ_SKIP; } +/* + * During cpu offlining and rq wide unthrottling, we can trigger + * an update_rq_clock() for several cfs and rt runqueues (Typically + * when using list_for_each_entry_*) + * rq_clock_start_loop_update() can be called after updating the clock + * once and before iterating over the list to prevent multiple update. + * After the iterative traversal, we need to call rq_clock_stop_loop_update() + * to clear RQCF_ACT_SKIP of rq->clock_update_flags. + */ +static inline void rq_clock_start_loop_update(struct rq *rq) +{ + lockdep_assert_rq_held(rq); + rq->clock_update_flags |= RQCF_ACT_SKIP; +} + +static inline void rq_clock_stop_loop_update(struct rq *rq) +{ + lockdep_assert_rq_held(rq); + rq->clock_update_flags &= ~RQCF_ACT_SKIP; +} + struct rq_flags { unsigned long flags; struct pin_cookie cookie; From patchwork Tue Jun 13 08:20:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hao Jia X-Patchwork-Id: 107200 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:994d:0:b0:3d9:f83d:47d9 with SMTP id k13csp396558vqr; Tue, 13 Jun 2023 01:56:44 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ7MP8tm7L4tBBv/F5CTptRcaWR30IhD42U1bjgSwgbWAF+eckhtkT3Ak8az99MYt6aS+dae X-Received: by 2002:a54:400a:0:b0:39a:b525:2a2e with SMTP id x10-20020a54400a000000b0039ab5252a2emr5963562oie.41.1686646604145; Tue, 13 Jun 2023 01:56:44 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1686646604; cv=none; d=google.com; s=arc-20160816; b=T5YoejUCE4byy5ZQjeCXuWtgNr4I8Tcf/JZbisQ4VV9dmGTcw8LiAbSsupI/rG6jqc 3Zfq5uwgMuVhlaHkpEQjpJmAsqBpGM+vwwm0qNAr9jFTuVicRnpS8f+4JoUAIoEV1DGz yiS6QHvs/WaHnhkYBgqv15TtWCUl9wYyPk0wWHaEqGARF8homvXH5v/cJmkT7JbDmeeu wMYqUQHKGJqFsCJM5WfAYnEB8UlBgCDJ0h/82xt9ZzZ3ffbNpPIboPK2i3QLmkCzq8pq dsoJbViKy3FnwiKGyYlqAdVlVdM1GqSc/Nno6966+EHSL6knJVyAxpo8cwr5kfztQnau Gnnw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=YmxLgmswZPkTWLyb16LsS4t5xijTdvKxqhRrgOY0CXw=; b=m8pRUzeAMwAzfJ4pvc4d28PCb0EvD1gv1JPad2evTD12z8iMhWZVGAfQIKKqq0Sjyc /hbQBVTjFL6qqxQcPLT2+m/5bNU6GTNwP7ZkYwg8CfWp3QoxDM4tsYhSiNKYDIu3N9Zq rqHFOn0ujNXaFFuf8uyz9qE6jyatayzcKbBHkrU6fKIUkD6qeE918S1gVYayOONOwpPC 77CZa2OfGoxt5BmnY1nZs5nmmt2SCy3NxPOBQo62rvciJztyXPvyujb2z/mj7gIY1BkH FA1wbCycvWazGGLxKBrjFbWBR8JyeJEQKPS/u7cVSoJvlKBkIJ8+IlyRwsTO5p7X5vbp N9lg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@bytedance.com header.s=google header.b=UNWb0MvV; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=bytedance.com Received: from out1.vger.email (out1.vger.email. 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Tue, 13 Jun 2023 01:20:49 -0700 (PDT) From: Hao Jia To: mingo@redhat.com, peterz@infradead.org, mingo@kernel.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, mgorman@techsingularity.net Cc: linux-kernel@vger.kernel.org, Hao Jia Subject: [PATCH v5 4/4] sched/core: Avoid multiple calling update_rq_clock() in unthrottle_offline_cfs_rqs() Date: Tue, 13 Jun 2023 16:20:12 +0800 Message-Id: <20230613082012.49615-5-jiahao.os@bytedance.com> X-Mailer: git-send-email 2.37.0 (Apple Git-136) In-Reply-To: <20230613082012.49615-1-jiahao.os@bytedance.com> References: <20230613082012.49615-1-jiahao.os@bytedance.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1768577149379395324?= X-GMAIL-MSGID: =?utf-8?q?1768577149379395324?= This WARN_DOUBLE_CLOCK warning is triggered during cpu offline. ------------[ cut here ]------------ rq->clock_update_flags & RQCF_UPDATED WARNING: CPU: 0 PID: 3323 at kernel/sched/core.c:741 update_rq_clock+0xaf/0x180 Call Trace: unthrottle_cfs_rq+0x4b/0x300 rq_offline_fair+0x89/0x90 set_rq_offline.part.118+0x28/0x60 rq_attach_root+0xc4/0xd0 cpu_attach_domain+0x3dc/0x7f0 partition_sched_domains_locked+0x2a5/0x3c0 rebuild_sched_domains_locked+0x477/0x830 rebuild_sched_domains+0x1b/0x30 cpuset_hotplug_workfn+0x2ca/0xc90 ? balance_push+0x56/0xf0 ? _raw_spin_unlock+0x15/0x30 ? finish_task_switch+0x98/0x2f0 ? __switch_to+0x291/0x410 ? __schedule+0x65e/0x1310 process_one_work+0x1bc/0x3d0 worker_thread+0x4c/0x380 ? preempt_count_add+0x92/0xa0 ? rescuer_thread+0x310/0x310 kthread+0xe6/0x110 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x1f/0x30 The rq clock has been updated in the set_rq_offline(), so we don't need to call update_rq_clock() in unthrottle_offline_cfs_rqs(). We only need to call rq_clock_start_loop_update() before the loop starts and rq_clock_stop_loop_update() after the loop to avoid this warning. Suggested-by: Vincent Guittot Signed-off-by: Hao Jia Reviewed-by: Vincent Guittot Reviewed-By: Ben Segall --- kernel/sched/fair.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index af9604f4b135..4da5f3541762 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6124,6 +6124,13 @@ static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq) lockdep_assert_rq_held(rq); + /* + * The rq clock has already been updated in the + * set_rq_offline(), so we should skip updating + * the rq clock again in unthrottle_cfs_rq(). + */ + rq_clock_start_loop_update(rq); + rcu_read_lock(); list_for_each_entry_rcu(tg, &task_groups, list) { struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; @@ -6146,6 +6153,8 @@ static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq) unthrottle_cfs_rq(cfs_rq); } rcu_read_unlock(); + + rq_clock_stop_loop_update(rq); } #else /* CONFIG_CFS_BANDWIDTH */