From patchwork Wed Oct 11 18:02:02 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Meng Xu X-Patchwork-Id: 10000295 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id EEEA360216 for ; Wed, 11 Oct 2017 18:04:47 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id ED20E28AFB for ; Wed, 11 Oct 2017 18:04:47 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E1F9528B00; Wed, 11 Oct 2017 18:04:47 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 23DA728AFB for ; Wed, 11 Oct 2017 18:04:47 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1e2LL3-0002yi-BV; Wed, 11 Oct 2017 18:02:37 +0000 Received: from mail6.bemta6.messagelabs.com ([193.109.254.103]) by lists.xenproject.org with esmtp (Exim 4.84_2) (envelope-from ) id 1e2LL2-0002xM-Cn for xen-devel@lists.xen.org; Wed, 11 Oct 2017 18:02:36 +0000 Received: from [193.109.254.147] by server-9.bemta-6.messagelabs.com id 6F/A3-30115-BBC5ED95; Wed, 11 Oct 2017 18:02:35 +0000 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrOLMWRWlGSWpSXmKPExsUyr8m9UXd7zL1 Igw1HtS2WfFzM4sDocXT3b6YAxijWzLyk/IoE1owlc34zFixKqrixyKOBcYJXFyMXh5BAP5NE x59JjF2MnBxsAioSxzc8YgWxRQSkJa59vswIUsQssJFRYvfxd+xdjBwcwgJ2Ejc+yYDUsAioS nx8dAasnlfAWeLR9e9sILaEgJzEyWOTweKcAi4Sz/+1MoO0CgHV/O4yhigJlViz+DwTTPnjhw 8YJzDyLGBkWMWoXpxaVJZapGupl1SUmZ5RkpuYmaNraGCml5taXJyYnpqTmFSsl5yfu4kR6HE GINjBeHdTwCFGSQ4mJVHeYL17kUJ8SfkplRmJxRnxRaU5qcWHGGU4OJQkeLujgXKCRanpqRVp mTnA0INJS3DwKInw6oKkeYsLEnOLM9MhUqcYLTk6bt79w8SxCUxu+P7gD5MQS15+XqqUOG8qS IMASENGaR7cOFh8XGKUlRLmZQQ6UIinILUoN7MEVf4VozgHo5Iw7xyQKTyZeSVwW18BHcQEdJ Bo2h2Qg0oSEVJSDYw5ijt3aWboSi0WkQyv/VT2/5HRg+kNmglrcnY9CJ607/CuFBGOcoller1 7AjTyZxxa75934gKf24fvHoLsdnouYX8i76hufVNS/exPcf1dC/+jnIU7153Y1qD82DE0sUD7 H2fQ3zl/jXZLaDUePl/CIhS4e73XGbvvk8qvrVIr+bktJ++jV54SS3FGoqEWc1FxIgA2rZ6fi gIAAA== X-Env-Sender: mengxu@cis.upenn.edu X-Msg-Ref: server-11.tower-27.messagelabs.com!1507744951!79412536!1 X-Originating-IP: [158.130.71.129] X-SpamReason: No, hits=0.0 required=7.0 tests= X-StarScan-Received: X-StarScan-Version: 9.4.45; banners=-,-,- X-VirusChecked: Checked Received: (qmail 12982 invoked from network); 11 Oct 2017 18:02:31 -0000 Received: from renard.seas.upenn.edu (HELO fox.seas.upenn.edu) (158.130.71.129) by server-11.tower-27.messagelabs.com with SMTP; 11 Oct 2017 18:02:31 -0000 Received: from panda-6c.cis.upenn.edu (SEASnet-48-12.cis.upenn.edu [158.130.48.13]) (authenticated bits=0) by fox.seas.upenn.edu (8.15.2/8.14.5) with ESMTPSA id v9BI2DV2017412 (version=TLSv1.2 cipher=AES256-SHA256 bits=256 verify=NOT); Wed, 11 Oct 2017 14:02:13 -0400 From: Meng Xu To: xen-devel@lists.xen.org Date: Wed, 11 Oct 2017 14:02:02 -0400 Message-Id: <1507744926-3950-2-git-send-email-mengxu@cis.upenn.edu> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1507744926-3950-1-git-send-email-mengxu@cis.upenn.edu> References: <1507744926-3950-1-git-send-email-mengxu@cis.upenn.edu> X-Proofpoint-Virus-Version: vendor=nai engine=5600 definitions=5800 signatures=585085 X-Proofpoint-Spam-Reason: safe Cc: wei.liu2@citrix.com, george.dunlap@eu.citrix.com, dario.faggioli@citrix.com, ian.jackson@eu.citrix.com, xumengpanda@gmail.com, Meng Xu Subject: [Xen-devel] [PATCH v4 1/5] xen:rtds: towards work conserving RTDS X-BeenThere: xen-devel@lists.xen.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP Make RTDS scheduler work conserving without breaking the real-time guarantees. VCPU model: Each real-time VCPU is extended to have an extratime flag and a priority_level field. When a VCPU's budget is depleted in the current period, if it has extratime flag set, its priority_level will increase by 1 and its budget will be refilled; othewrise, the VCPU will be moved to the depletedq. Scheduling policy is modified global EDF: A VCPU v1 has higher priority than another VCPU v2 if (i) v1 has smaller priority_leve; or (ii) v1 has the same priority_level but has a smaller deadline Queue management: Run queue holds VCPUs with extratime flag set and VCPUs with remaining budget. Run queue is sorted in increasing order of VCPUs priorities. Depleted queue holds VCPUs which have extratime flag cleared and depleted budget. Replenished queue is not modified. Distribution of spare bandwidth Spare bandwidth is distributed among all VCPUs with extratime flag set, proportional to these VCPUs utilizations Signed-off-by: Meng Xu Reviewed-by: Dario Faggioli --- Changes from v2 Explain how to distribute spare bandwidth in commit log Minor change in has_extratime function without functionality change. Changes from v1 Change XEN_DOMCTL_SCHED_RTDS_extratime to XEN_DOMCTL_SCHEDRT_extra as suggested by Dario Changes from RFC v1 Rewording comments and commit message Remove is_work_conserving field from rt_vcpu structure Use one bit in VCPU's flag to indicate if a VCPU will have extra time Correct comments style --- xen/common/sched_rt.c | 90 ++++++++++++++++++++++++++++++++++++++------- xen/include/public/domctl.h | 4 ++ 2 files changed, 80 insertions(+), 14 deletions(-) diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c index 5c51cd9..b770287 100644 --- a/xen/common/sched_rt.c +++ b/xen/common/sched_rt.c @@ -49,13 +49,15 @@ * A PCPU is feasible if the VCPU can run on this PCPU and (the PCPU is idle or * has a lower-priority VCPU running on it.) * - * Each VCPU has a dedicated period and budget. + * Each VCPU has a dedicated period, budget and a extratime flag * The deadline of a VCPU is at the end of each period; * A VCPU has its budget replenished at the beginning of each period; * While scheduled, a VCPU burns its budget. * The VCPU needs to finish its budget before its deadline in each period; * The VCPU discards its unused budget at the end of each period. - * If a VCPU runs out of budget in a period, it has to wait until next period. + * When a VCPU runs out of budget in a period, if its extratime flag is set, + * the VCPU increases its priority_level by 1 and refills its budget; otherwise, + * it has to wait until next period. * * Each VCPU is implemented as a deferable server. * When a VCPU has a task running on it, its budget is continuously burned; @@ -63,7 +65,8 @@ * * Queue scheme: * A global runqueue and a global depletedqueue for each CPU pool. - * The runqueue holds all runnable VCPUs with budget, sorted by deadline; + * The runqueue holds all runnable VCPUs with budget, + * sorted by priority_level and deadline; * The depletedqueue holds all VCPUs without budget, unsorted; * * Note: cpumask and cpupool is supported. @@ -151,6 +154,14 @@ #define RTDS_depleted (1<<__RTDS_depleted) /* + * RTDS_extratime: Can the vcpu run in the time that is + * not part of any real-time reservation, and would therefore + * be otherwise left idle? + */ +#define __RTDS_extratime 4 +#define RTDS_extratime (1<<__RTDS_extratime) + +/* * rt tracing events ("only" 512 available!). Check * include/public/trace.h for more details. */ @@ -201,6 +212,8 @@ struct rt_vcpu { struct rt_dom *sdom; struct vcpu *vcpu; + unsigned priority_level; + unsigned flags; /* mark __RTDS_scheduled, etc.. */ }; @@ -245,6 +258,11 @@ static inline struct list_head *rt_replq(const struct scheduler *ops) return &rt_priv(ops)->replq; } +static inline bool has_extratime(const struct rt_vcpu *svc) +{ + return svc->flags & RTDS_extratime; +} + /* * Helper functions for manipulating the runqueue, the depleted queue, * and the replenishment events queue. @@ -274,6 +292,21 @@ vcpu_on_replq(const struct rt_vcpu *svc) } /* + * If v1 priority >= v2 priority, return value > 0 + * Otherwise, return value < 0 + */ +static s_time_t +compare_vcpu_priority(const struct rt_vcpu *v1, const struct rt_vcpu *v2) +{ + int prio = v2->priority_level - v1->priority_level; + + if ( prio == 0 ) + return v2->cur_deadline - v1->cur_deadline; + + return prio; +} + +/* * Debug related code, dump vcpu/cpu information */ static void @@ -303,6 +336,7 @@ rt_dump_vcpu(const struct scheduler *ops, const struct rt_vcpu *svc) cpulist_scnprintf(keyhandler_scratch, sizeof(keyhandler_scratch), mask); printk("[%5d.%-2u] cpu %u, (%"PRI_stime", %"PRI_stime")," " cur_b=%"PRI_stime" cur_d=%"PRI_stime" last_start=%"PRI_stime"\n" + " \t\t priority_level=%d has_extratime=%d\n" " \t\t onQ=%d runnable=%d flags=%x effective hard_affinity=%s\n", svc->vcpu->domain->domain_id, svc->vcpu->vcpu_id, @@ -312,6 +346,8 @@ rt_dump_vcpu(const struct scheduler *ops, const struct rt_vcpu *svc) svc->cur_budget, svc->cur_deadline, svc->last_start, + svc->priority_level, + has_extratime(svc), vcpu_on_q(svc), vcpu_runnable(svc->vcpu), svc->flags, @@ -423,15 +459,18 @@ rt_update_deadline(s_time_t now, struct rt_vcpu *svc) */ svc->last_start = now; svc->cur_budget = svc->budget; + svc->priority_level = 0; /* TRACE */ { struct __packed { unsigned vcpu:16, dom:16; + unsigned priority_level; uint64_t cur_deadline, cur_budget; } d; d.dom = svc->vcpu->domain->domain_id; d.vcpu = svc->vcpu->vcpu_id; + d.priority_level = svc->priority_level; d.cur_deadline = (uint64_t) svc->cur_deadline; d.cur_budget = (uint64_t) svc->cur_budget; trace_var(TRC_RTDS_BUDGET_REPLENISH, 1, @@ -454,7 +493,7 @@ rt_update_deadline(s_time_t now, struct rt_vcpu *svc) * cases, if the vcpu with the earliest deadline is what we * are dealing with). */ -static inline bool_t +static inline bool deadline_queue_remove(struct list_head *queue, struct list_head *elem) { int pos = 0; @@ -466,7 +505,7 @@ deadline_queue_remove(struct list_head *queue, struct list_head *elem) return !pos; } -static inline bool_t +static inline bool deadline_queue_insert(struct rt_vcpu * (*qelem)(struct list_head *), struct rt_vcpu *svc, struct list_head *elem, struct list_head *queue) @@ -477,7 +516,7 @@ deadline_queue_insert(struct rt_vcpu * (*qelem)(struct list_head *), list_for_each ( iter, queue ) { struct rt_vcpu * iter_svc = (*qelem)(iter); - if ( svc->cur_deadline <= iter_svc->cur_deadline ) + if ( compare_vcpu_priority(svc, iter_svc) > 0 ) break; pos++; } @@ -537,8 +576,9 @@ runq_insert(const struct scheduler *ops, struct rt_vcpu *svc) ASSERT( !vcpu_on_q(svc) ); ASSERT( vcpu_on_replq(svc) ); - /* add svc to runq if svc still has budget */ - if ( svc->cur_budget > 0 ) + /* add svc to runq if svc still has budget or its extratime is set */ + if ( svc->cur_budget > 0 || + has_extratime(svc) ) deadline_runq_insert(svc, &svc->q_elem, runq); else list_add(&svc->q_elem, &prv->depletedq); @@ -857,6 +897,8 @@ rt_alloc_vdata(const struct scheduler *ops, struct vcpu *vc, void *dd) svc->vcpu = vc; svc->last_start = 0; + __set_bit(__RTDS_extratime, &svc->flags); + svc->priority_level = 0; svc->period = RTDS_DEFAULT_PERIOD; if ( !is_idle_vcpu(vc) ) svc->budget = RTDS_DEFAULT_BUDGET; @@ -966,8 +1008,16 @@ burn_budget(const struct scheduler *ops, struct rt_vcpu *svc, s_time_t now) if ( svc->cur_budget <= 0 ) { - svc->cur_budget = 0; - __set_bit(__RTDS_depleted, &svc->flags); + if ( has_extratime(svc) ) + { + svc->priority_level++; + svc->cur_budget = svc->budget; + } + else + { + svc->cur_budget = 0; + __set_bit(__RTDS_depleted, &svc->flags); + } } /* TRACE */ @@ -976,11 +1026,15 @@ burn_budget(const struct scheduler *ops, struct rt_vcpu *svc, s_time_t now) unsigned vcpu:16, dom:16; uint64_t cur_budget; int delta; + unsigned priority_level; + bool has_extratime; } d; d.dom = svc->vcpu->domain->domain_id; d.vcpu = svc->vcpu->vcpu_id; d.cur_budget = (uint64_t) svc->cur_budget; d.delta = delta; + d.priority_level = svc->priority_level; + d.has_extratime = svc->flags & RTDS_extratime; trace_var(TRC_RTDS_BUDGET_BURN, 1, sizeof(d), (unsigned char *) &d); @@ -1088,7 +1142,7 @@ rt_schedule(const struct scheduler *ops, s_time_t now, bool_t tasklet_work_sched vcpu_runnable(current) && scurr->cur_budget > 0 && ( is_idle_vcpu(snext->vcpu) || - scurr->cur_deadline <= snext->cur_deadline ) ) + compare_vcpu_priority(scurr, snext) > 0 ) ) snext = scurr; } @@ -1194,7 +1248,7 @@ runq_tickle(const struct scheduler *ops, struct rt_vcpu *new) } iter_svc = rt_vcpu(iter_vc); if ( latest_deadline_vcpu == NULL || - iter_svc->cur_deadline > latest_deadline_vcpu->cur_deadline ) + compare_vcpu_priority(iter_svc, latest_deadline_vcpu) < 0 ) latest_deadline_vcpu = iter_svc; cpumask_clear_cpu(cpu, ¬_tickled); @@ -1203,7 +1257,7 @@ runq_tickle(const struct scheduler *ops, struct rt_vcpu *new) /* 2) candicate has higher priority, kick out lowest priority vcpu */ if ( latest_deadline_vcpu != NULL && - new->cur_deadline < latest_deadline_vcpu->cur_deadline ) + compare_vcpu_priority(latest_deadline_vcpu, new) < 0 ) { SCHED_STAT_CRANK(tickled_busy_cpu); cpu_to_tickle = latest_deadline_vcpu->vcpu->processor; @@ -1394,6 +1448,10 @@ rt_dom_cntl( svc = rt_vcpu(d->vcpu[local_sched.vcpuid]); local_sched.u.rtds.budget = svc->budget / MICROSECS(1); local_sched.u.rtds.period = svc->period / MICROSECS(1); + if ( has_extratime(svc) ) + local_sched.u.rtds.flags |= XEN_DOMCTL_SCHEDRT_extra; + else + local_sched.u.rtds.flags &= ~XEN_DOMCTL_SCHEDRT_extra; spin_unlock_irqrestore(&prv->lock, flags); if ( copy_to_guest_offset(op->u.v.vcpus, index, @@ -1418,6 +1476,10 @@ rt_dom_cntl( svc = rt_vcpu(d->vcpu[local_sched.vcpuid]); svc->period = period; svc->budget = budget; + if ( local_sched.u.rtds.flags & XEN_DOMCTL_SCHEDRT_extra ) + __set_bit(__RTDS_extratime, &svc->flags); + else + __clear_bit(__RTDS_extratime, &svc->flags); spin_unlock_irqrestore(&prv->lock, flags); } /* Process a most 64 vCPUs without checking for preemptions. */ @@ -1492,7 +1554,7 @@ static void repl_timer_handler(void *data){ { struct rt_vcpu *next_on_runq = q_elem(runq->next); - if ( svc->cur_deadline > next_on_runq->cur_deadline ) + if ( compare_vcpu_priority(svc, next_on_runq) < 0 ) runq_tickle(ops, next_on_runq); } else if ( __test_and_clear_bit(__RTDS_depleted, &svc->flags) && diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h index 8853445..70027ab 100644 --- a/xen/include/public/domctl.h +++ b/xen/include/public/domctl.h @@ -342,6 +342,10 @@ struct xen_domctl_sched_credit2 { struct xen_domctl_sched_rtds { uint32_t period; uint32_t budget; +/* Can this vCPU execute beyond its reserved amount of time? */ +#define _XEN_DOMCTL_SCHEDRT_extra 0 +#define XEN_DOMCTL_SCHEDRT_extra (1U<<_XEN_DOMCTL_SCHEDRT_extra) + uint32_t flags; }; typedef struct xen_domctl_schedparam_vcpu {