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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2 1/4] xen: add real time scheduler rt
This scheduler follows the Preemptive Global Earliest Deadline First
(EDF) theory in real-time field.
At any scheduling point, the VCPU with earlier deadline has higher
priority. The scheduler always picks the highest priority VCPU to run on a
feasible PCPU.
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.
The deadline of a VCPU is at the end of each of its periods;
A VCPU has its budget replenished at the beginning of each of its periods;
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 of its periods.
If a VCPU runs out of budget in a period, 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;
When a VCPU has no task but with budget left, its budget is preserved.
Queue scheme: A global runqueue for each CPU pool.
The runqueue holds all runnable VCPUs.
VCPUs in the runqueue are divided into two parts: with and without budget.
At the first part, VCPUs are sorted based on EDF priority scheme.
Note: cpumask and cpupool is supported.
This is an experimental scheduler.
Signed-off-by: Meng Xu <mengxu@xxxxxxxxxxxxx>
Signed-off-by: Sisu Xi <xisisu@xxxxxxxxx>
---
xen/common/Makefile | 1 +
xen/common/sched_rt.c | 1146 +++++++++++++++++++++++++++++++++++++++++++
xen/common/schedule.c | 1 +
xen/include/public/domctl.h | 6 +
xen/include/public/trace.h | 1 +
xen/include/xen/sched-if.h | 1 +
6 files changed, 1156 insertions(+)
create mode 100644 xen/common/sched_rt.c
diff --git a/xen/common/Makefile b/xen/common/Makefile
index 3683ae3..5a23aa4 100644
--- a/xen/common/Makefile
+++ b/xen/common/Makefile
@@ -26,6 +26,7 @@ obj-y += sched_credit.o
obj-y += sched_credit2.o
obj-y += sched_sedf.o
obj-y += sched_arinc653.o
+obj-y += sched_rt.o
obj-y += schedule.o
obj-y += shutdown.o
obj-y += softirq.o
diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c
new file mode 100644
index 0000000..412f8b1
--- /dev/null
+++ b/xen/common/sched_rt.c
@@ -0,0 +1,1146 @@
+/******************************************************************************
+ * Preemptive Global Earliest Deadline First (EDF) scheduler for Xen
+ * EDF scheduling is a real-time scheduling algorithm used in embedded field.
+ *
+ * by Sisu Xi, 2013, Washington University in Saint Louis
+ * and Meng Xu, 2014, University of Pennsylvania
+ *
+ * based on the code of credit Scheduler
+ */
+
+#include <xen/config.h>
+#include <xen/init.h>
+#include <xen/lib.h>
+#include <xen/sched.h>
+#include <xen/domain.h>
+#include <xen/delay.h>
+#include <xen/event.h>
+#include <xen/time.h>
+#include <xen/perfc.h>
+#include <xen/sched-if.h>
+#include <xen/softirq.h>
+#include <asm/atomic.h>
+#include <xen/errno.h>
+#include <xen/trace.h>
+#include <xen/cpu.h>
+#include <xen/keyhandler.h>
+#include <xen/trace.h>
+#include <xen/guest_access.h>
+
+/*
+ * TODO:
+ *
+ * Migration compensation and resist like credit2 to better use cache;
+ * Lock Holder Problem, using yield?
+ * Self switch problem: VCPUs of the same domain may preempt each other;
+ */
+
+/*
+ * Design:
+ *
+ * This scheduler follows the Preemptive Global Earliest Deadline First (EDF)
+ * theory in real-time field.
+ * At any scheduling point, the VCPU with earlier deadline has higher priority.
+ * The scheduler always picks highest priority VCPU to run on a feasible PCPU.
+ * 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.
+ * The deadline of a VCPU is at the end of each of its periods;
+ * A VCPU has its budget replenished at the beginning of each of its periods;
+ * 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 of its periods.
+ * If a VCPU runs out of budget in a period, 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;
+ * When a VCPU has no task but with budget left, its budget is preserved.
+ *
+ * Queue scheme: A global runqueue for each CPU pool.
+ * The runqueue holds all runnable VCPUs.
+ * VCPUs in the runqueue are divided into two parts:
+ * with and without remaining budget.
+ * At the first part, VCPUs are sorted based on EDF priority scheme.
+ *
+ * Note: cpumask and cpupool is supported.
+ */
+
+/*
+ * Locking:
+ * A global system lock is used to protect the RunQ.
+ * The global lock is referenced by schedule_data.schedule_lock
+ * from all physical cpus.
+ *
+ * The lock is already grabbed when calling wake/sleep/schedule/ functions
+ * in schedule.c
+ *
+ * The functions involes RunQ and needs to grab locks are:
+ * vcpu_insert, vcpu_remove, context_saved, __runq_insert
+ */
+
+
+/*
+ * Default parameters:
+ * Period and budget in default is 10 and 4 ms, respectively
+ */
+#define RT_DS_DEFAULT_PERIOD (MICROSECS(10000))
+#define RT_DS_DEFAULT_BUDGET (MICROSECS(4000))
+
+/*
+ * Flags
+ */
+/*
+ * RT_scheduled: Is this vcpu either running on, or context-switching off,
+ * a phyiscal cpu?
+ * + Accessed only with Runqueue lock held.
+ * + Set when chosen as next in rt_schedule().
+ * + Cleared after context switch has been saved in rt_context_saved()
+ * + Checked in vcpu_wake to see if we can add to the Runqueue, or if we should
+ * set RT_delayed_runq_add
+ * + Checked to be false in runq_insert.
+ */
+#define __RT_scheduled 1
+#define RT_scheduled (1<<__RT_scheduled)
+/*
+ * RT_delayed_runq_add: Do we need to add this to the Runqueueu once it'd done
+ * being context switching out?
+ * + Set when scheduling out in rt_schedule() if prev is runable
+ * + Set in rt_vcpu_wake if it finds RT_scheduled set
+ * + Read in rt_context_saved(). If set, it adds prev to the Runqueue and
+ * clears the bit.
+ */
+#define __RT_delayed_runq_add 2
+#define RT_delayed_runq_add (1<<__RT_delayed_runq_add)
+
+/*
+ * Debug only. Used to printout debug information
+ */
+#define printtime()\
+ ({s_time_t now = NOW(); \
+ printk("%u : %3ld.%3ldus : %-19s\n",smp_processor_id(),\
+ now/MICROSECS(1), now%MICROSECS(1)/1000, __func__);} )
+
+/*
+ * rt tracing events ("only" 512 available!). Check
+ * include/public/trace.h for more details.
+ */
+#define TRC_RT_TICKLE TRC_SCHED_CLASS_EVT(RT, 1)
+#define TRC_RT_RUNQ_PICK TRC_SCHED_CLASS_EVT(RT, 2)
+#define TRC_RT_BUDGET_BURN TRC_SCHED_CLASS_EVT(RT, 3)
+#define TRC_RT_BUDGET_REPLENISH TRC_SCHED_CLASS_EVT(RT, 4)
+#define TRC_RT_SCHED_TASKLET TRC_SCHED_CLASS_EVT(RT, 5)
+#define TRC_RT_VCPU_DUMP TRC_SCHED_CLASS_EVT(RT, 6)
+
+/*
+ * Systme-wide private data, include a global RunQueue
+ * Global lock is referenced by schedule_data.schedule_lock from all
+ * physical cpus. It can be grabbed via vcpu_schedule_lock_irq()
+ */
+struct rt_private {
+ spinlock_t lock; /* The global coarse grand lock */
+ struct list_head sdom; /* list of availalbe domains, used for dump */
+ struct list_head runq; /* Ordered list of runnable VMs */
+ struct rt_vcpu *flag_vcpu; /* position of the first depleted vcpu */
+ cpumask_t cpus; /* cpumask_t of available physical cpus */
+ cpumask_t tickled; /* cpus been tickled */
+};
+
+/*
+ * Virtual CPU
+ */
+struct rt_vcpu {
+ struct list_head runq_elem; /* On the runqueue list */
+ struct list_head sdom_elem; /* On the domain VCPU list */
+
+ /* Up-pointers */
+ struct rt_dom *sdom;
+ struct vcpu *vcpu;
+
+ /* VCPU parameters, in nanoseconds */
+ s_time_t period;
+ s_time_t budget;
+
+ /* VCPU current infomation in nanosecond */
+ s_time_t cur_budget; /* current budget */
+ s_time_t last_start; /* last start time */
+ s_time_t cur_deadline; /* current deadline for EDF */
+
+ unsigned flags; /* mark __RT_scheduled, etc.. */
+};
+
+/*
+ * Domain
+ */
+struct rt_dom {
+ struct list_head vcpu; /* link its VCPUs */
+ struct list_head sdom_elem; /* link list on rt_priv */
+ struct domain *dom; /* pointer to upper domain */
+};
+
+/*
+ * Useful inline functions
+ */
+static inline struct rt_private *RT_PRIV(const struct scheduler *ops)
+{
+ return ops->sched_data;
+}
+
+static inline struct rt_vcpu *RT_VCPU(const struct vcpu *vcpu)
+{
+ return vcpu->sched_priv;
+}
+
+static inline struct rt_dom *RT_DOM(const struct domain *dom)
+{
+ return dom->sched_priv;
+}
+
+static inline struct list_head *RUNQ(const struct scheduler *ops)
+{
+ return &RT_PRIV(ops)->runq;
+}
+
+/*
+ * RunQueue helper functions
+ */
+static int
+__vcpu_on_runq(const struct rt_vcpu *svc)
+{
+ return !list_empty(&svc->runq_elem);
+}
+
+static struct rt_vcpu *
+__runq_elem(struct list_head *elem)
+{
+ return list_entry(elem, struct rt_vcpu, runq_elem);
+}
+
+/*
+ * Debug related code, dump vcpu/cpu information
+ */
+static void
+rt_dump_vcpu(const struct scheduler *ops, const struct rt_vcpu *svc)
+{
+ struct rt_private *prv = RT_PRIV(ops);
+ char cpustr[1024];
+ cpumask_t *cpupool_mask;
+
+ ASSERT(svc != NULL);
+ /* flag vcpu */
+ if( svc->sdom == NULL )
+ return;
+
+ cpumask_scnprintf(cpustr, sizeof(cpustr), svc->vcpu->cpu_hard_affinity);
+ printk("[%5d.%-2u] cpu %u, (%"PRI_stime", %"PRI_stime"),"
+ " cur_b=%"PRI_stime" cur_d=%"PRI_stime" last_start=%"PRI_stime
+ " onR=%d runnable=%d cpu_hard_affinity=%s ",
+ svc->vcpu->domain->domain_id,
+ svc->vcpu->vcpu_id,
+ svc->vcpu->processor,
+ svc->period,
+ svc->budget,
+ svc->cur_budget,
+ svc->cur_deadline,
+ svc->last_start,
+ __vcpu_on_runq(svc),
+ vcpu_runnable(svc->vcpu),
+ cpustr);
+ memset(cpustr, 0, sizeof(cpustr));
+ cpupool_mask = cpupool_scheduler_cpumask(svc->vcpu->domain->cpupool);
+ cpumask_scnprintf(cpustr, sizeof(cpustr), cpupool_mask);
+ printk("cpupool=%s ", cpustr);
+ memset(cpustr, 0, sizeof(cpustr));
+ cpumask_scnprintf(cpustr, sizeof(cpustr), &prv->cpus);
+ printk("prv->cpus=%s\n", cpustr);
+
+ /* TRACE */
+ {
+ struct {
+ unsigned dom:16,vcpu:16;
+ unsigned processor;
+ unsigned cur_budget_lo, cur_budget_hi;
+ unsigned cur_deadline_lo, cur_deadline_hi;
+ unsigned is_vcpu_on_runq:16,is_vcpu_runnable:16;
+ } d;
+ d.dom = svc->vcpu->domain->domain_id;
+ d.vcpu = svc->vcpu->vcpu_id;
+ d.processor = svc->vcpu->processor;
+ d.cur_budget_lo = (unsigned) svc->cur_budget;
+ d.cur_budget_hi = (unsigned) (svc->cur_budget >> 32);
+ d.cur_deadline_lo = (unsigned) svc->cur_deadline;
+ d.cur_deadline_hi = (unsigned) (svc->cur_deadline >> 32);
+ d.is_vcpu_on_runq = __vcpu_on_runq(svc);
+ d.is_vcpu_runnable = vcpu_runnable(svc->vcpu);
+ trace_var(TRC_RT_VCPU_DUMP, 1,
+ sizeof(d),
+ (unsigned char *)&d);
+ }
+}
+
+static void
+rt_dump_pcpu(const struct scheduler *ops, int cpu)
+{
+ struct rt_vcpu *svc = RT_VCPU(curr_on_cpu(cpu));
+
+ printtime();
+ rt_dump_vcpu(ops, svc);
+}
+
+/*
+ * should not need lock here. only showing stuff
+ */
+static void
+rt_dump(const struct scheduler *ops)
+{
+ struct list_head *iter_sdom, *iter_svc, *runq, *iter;
+ struct rt_private *prv = RT_PRIV(ops);
+ struct rt_vcpu *svc;
+ unsigned int cpu = 0;
+
+ printtime();
+
+ printk("PCPU info:\n");
+ for_each_cpu(cpu, &prv->cpus)
+ rt_dump_pcpu(ops, cpu);
+
+ printk("Global RunQueue info:\n");
+ runq = RUNQ(ops);
+ list_for_each( iter, runq )
+ {
+ svc = __runq_elem(iter);
+ rt_dump_vcpu(ops, svc);
+ }
+
+ printk("Domain info:\n");
+ list_for_each( iter_sdom, &prv->sdom )
+ {
+ struct rt_dom *sdom;
+ sdom = list_entry(iter_sdom, struct rt_dom, sdom_elem);
+ printk("\tdomain: %d\n", sdom->dom->domain_id);
+
+ list_for_each( iter_svc, &sdom->vcpu )
+ {
+ svc = list_entry(iter_svc, struct rt_vcpu, sdom_elem);
+ rt_dump_vcpu(ops, svc);
+ }
+ }
+
+ printk("\n");
+}
+
+/*
+ * update deadline and budget when deadline is in the past,
+ * it need to be updated to the deadline of the current period
+ */
+static void
+rt_update_helper(s_time_t now, struct rt_vcpu *svc)
+{
+ s_time_t diff = now - svc->cur_deadline;
+
+ if ( diff >= 0 )
+ {
+ /* now can be later for several periods */
+ long count = ( diff/svc->period ) + 1;
+ svc->cur_deadline += count * svc->period;
+ svc->cur_budget = svc->budget;
+
+ /* TRACE */
+ {
+ struct {
+ unsigned dom:16,vcpu:16;
+ unsigned cur_budget_lo, cur_budget_hi;
+ } d;
+ d.dom = svc->vcpu->domain->domain_id;
+ d.vcpu = svc->vcpu->vcpu_id;
+ d.cur_budget_lo = (unsigned) svc->cur_budget;
+ d.cur_budget_hi = (unsigned) (svc->cur_budget >> 32);
+ trace_var(TRC_RT_BUDGET_REPLENISH, 1,
+ sizeof(d),
+ (unsigned char *) &d);
+ }
+
+ return;
+ }
+}
+
+static inline void
+__runq_remove(struct rt_vcpu *svc)
+{
+ if ( __vcpu_on_runq(svc) )
+ list_del_init(&svc->runq_elem);
+}
+
+/*
+ * Insert svc in the RunQ according to EDF: vcpus with smaller deadlines
+ * goes first.
+ */
+static void
+__runq_insert(const struct scheduler *ops, struct rt_vcpu *svc)
+{
+ struct rt_private *prv = RT_PRIV(ops);
+ struct list_head *runq = RUNQ(ops);
+ struct list_head *iter;
+ spinlock_t *schedule_lock;
+
+ schedule_lock = per_cpu(schedule_data, svc->vcpu->processor).schedule_lock;
+ ASSERT( spin_is_locked(schedule_lock) );
+
+ ASSERT( !__vcpu_on_runq(svc) );
+
+ /* svc still has budget */
+ if ( svc->cur_budget > 0 )
+ {
+ list_for_each(iter, runq)
+ {
+ struct rt_vcpu * iter_svc = __runq_elem(iter);
+ if ( iter_svc->cur_budget == 0 ||
+ svc->cur_deadline <= iter_svc->cur_deadline )
+ break;
+ }
+ list_add_tail(&svc->runq_elem, iter);
+ }
+ else
+ {
+ list_add(&svc->runq_elem, &prv->flag_vcpu->runq_elem);
+ }
+}
+
+/*
+ * Init/Free related code
+ */
+static int
+rt_init(struct scheduler *ops)
+{
+ struct rt_private *prv = xzalloc(struct rt_private);
+
+ printk("Initializing RT scheduler\n" \
+ " WARNING: This is experimental software in development.\n" \
+ " Use at your own risk.\n");
+
+ if ( prv == NULL )
+ return -ENOMEM;
+
+ spin_lock_init(&prv->lock);
+ INIT_LIST_HEAD(&prv->sdom);
+ INIT_LIST_HEAD(&prv->runq);
+
+ prv->flag_vcpu = xzalloc(struct rt_vcpu);
+ prv->flag_vcpu->cur_budget = 0;
+ prv->flag_vcpu->sdom = NULL; /* distinguish this vcpu with others */
+ list_add(&prv->flag_vcpu->runq_elem, &prv->runq);
+
+ cpumask_clear(&prv->cpus);
+ cpumask_clear(&prv->tickled);
+
+ ops->sched_data = prv;
+
+ printtime();
+ printk("\n");
+
+ return 0;
+}
+
+static void
+rt_deinit(const struct scheduler *ops)
+{
+ struct rt_private *prv = RT_PRIV(ops);
+
+ printtime();
+ printk("\n");
+ xfree(prv->flag_vcpu);
+ xfree(prv);
+}
+
+/*
+ * Point per_cpu spinlock to the global system lock;
+ * All cpu have same global system lock
+ */
+static void *
+rt_alloc_pdata(const struct scheduler *ops, int cpu)
+{
+ struct rt_private *prv = RT_PRIV(ops);
+
+ cpumask_set_cpu(cpu, &prv->cpus);
+
+ per_cpu(schedule_data, cpu).schedule_lock = &prv->lock;
+
+ printtime();
+ printk("%s total cpus: %d", __func__, cpumask_weight(&prv->cpus));
+ /* 1 indicates alloc. succeed in schedule.c */
+ return (void *)1;
+}
+
+static void
+rt_free_pdata(const struct scheduler *ops, void *pcpu, int cpu)
+{
+ struct rt_private * prv = RT_PRIV(ops);
+ cpumask_clear_cpu(cpu, &prv->cpus);
+}
+
+static void *
+rt_alloc_domdata(const struct scheduler *ops, struct domain *dom)
+{
+ unsigned long flags;
+ struct rt_dom *sdom;
+ struct rt_private * prv = RT_PRIV(ops);
+
+ sdom = xzalloc(struct rt_dom);
+ if ( sdom == NULL )
+ {
+ printk("%s, xzalloc failed\n", __func__);
+ return NULL;
+ }
+
+ INIT_LIST_HEAD(&sdom->vcpu);
+ INIT_LIST_HEAD(&sdom->sdom_elem);
+ sdom->dom = dom;
+
+ /* spinlock here to insert the dom */
+ spin_lock_irqsave(&prv->lock, flags);
+ list_add_tail(&sdom->sdom_elem, &(prv->sdom));
+ spin_unlock_irqrestore(&prv->lock, flags);
+
+ return sdom;
+}
+
+static void
+rt_free_domdata(const struct scheduler *ops, void *data)
+{
+ unsigned long flags;
+ struct rt_dom *sdom = data;
+ struct rt_private *prv = RT_PRIV(ops);
+
+ spin_lock_irqsave(&prv->lock, flags);
+ list_del_init(&sdom->sdom_elem);
+ spin_unlock_irqrestore(&prv->lock, flags);
+ xfree(data);
+}
+
+static int
+rt_dom_init(const struct scheduler *ops, struct domain *dom)
+{
+ struct rt_dom *sdom;
+
+ /* IDLE Domain does not link on rt_private */
+ if ( is_idle_domain(dom) )
+ return 0;
+
+ sdom = rt_alloc_domdata(ops, dom);
+ if ( sdom == NULL )
+ {
+ printk("%s, failed\n", __func__);
+ return -ENOMEM;
+ }
+ dom->sched_priv = sdom;
+
+ return 0;
+}
+
+static void
+rt_dom_destroy(const struct scheduler *ops, struct domain *dom)
+{
+ rt_free_domdata(ops, RT_DOM(dom));
+}
+
+static void *
+rt_alloc_vdata(const struct scheduler *ops, struct vcpu *vc, void *dd)
+{
+ struct rt_vcpu *svc;
+ s_time_t now = NOW();
+
+ /* Allocate per-VCPU info */
+ svc = xzalloc(struct rt_vcpu);
+ if ( svc == NULL )
+ {
+ printk("%s, xzalloc failed\n", __func__);
+ return NULL;
+ }
+
+ INIT_LIST_HEAD(&svc->runq_elem);
+ INIT_LIST_HEAD(&svc->sdom_elem);
+ svc->flags = 0U;
+ svc->sdom = dd;
+ svc->vcpu = vc;
+ svc->last_start = 0;
+
+ svc->period = RT_DS_DEFAULT_PERIOD;
+ if ( !is_idle_vcpu(vc) )
+ svc->budget = RT_DS_DEFAULT_BUDGET;
+
+ rt_update_helper(now, svc);
+
+ /* Debug only: dump new vcpu's info */
+ rt_dump_vcpu(ops, svc);
+
+ return svc;
+}
+
+static void
+rt_free_vdata(const struct scheduler *ops, void *priv)
+{
+ struct rt_vcpu *svc = priv;
+
+ /* Debug only: dump freed vcpu's info */
+ rt_dump_vcpu(ops, svc);
+ xfree(svc);
+}
+
+/*
+ * This function is called in sched_move_domain() in schedule.c
+ * When move a domain to a new cpupool.
+ * It inserts vcpus of moving domain to the scheduler's RunQ in
+ * dest. cpupool; and insert rt_vcpu svc to scheduler-specific
+ * vcpu list of the dom
+ */
+static void
+rt_vcpu_insert(const struct scheduler *ops, struct vcpu *vc)
+{
+ struct rt_vcpu *svc = RT_VCPU(vc);
+
+ /* Debug only: dump info of vcpu to insert */
+ rt_dump_vcpu(ops, svc);
+
+ /* not addlocate idle vcpu to dom vcpu list */
+ if ( is_idle_vcpu(vc) )
+ return;
+
+ if ( !__vcpu_on_runq(svc) && vcpu_runnable(vc) && !vc->is_running )
+ __runq_insert(ops, svc);
+
+ /* add rt_vcpu svc to scheduler-specific vcpu list of the dom */
+ list_add_tail(&svc->sdom_elem, &svc->sdom->vcpu);
+}
+
+/*
+ * Remove rt_vcpu svc from the old scheduler in source cpupool; and
+ * Remove rt_vcpu svc from scheduler-specific vcpu list of the dom
+ */
+static void
+rt_vcpu_remove(const struct scheduler *ops, struct vcpu *vc)
+{
+ struct rt_vcpu * const svc = RT_VCPU(vc);
+ struct rt_dom * const sdom = svc->sdom;
+
+ rt_dump_vcpu(ops, svc);
+
+ BUG_ON( sdom == NULL );
+ BUG_ON( __vcpu_on_runq(svc) );
+
+ if ( __vcpu_on_runq(svc) )
+ __runq_remove(svc);
+
+ if ( !is_idle_vcpu(vc) )
+ list_del_init(&svc->sdom_elem);
+}
+
+/*
+ * Pick a valid CPU for the vcpu vc
+ * Valid CPU of a vcpu is intesection of vcpu's affinity
+ * and available cpus
+ */
+static int
+rt_cpu_pick(const struct scheduler *ops, struct vcpu *vc)
+{
+ cpumask_t cpus;
+ cpumask_t *online;
+ int cpu;
+ struct rt_private * prv = RT_PRIV(ops);
+
+ online = cpupool_scheduler_cpumask(vc->domain->cpupool);
+ cpumask_and(&cpus, &prv->cpus, online);
+ cpumask_and(&cpus, &cpus, vc->cpu_hard_affinity);
+
+ cpu = cpumask_test_cpu(vc->processor, &cpus)
+ ? vc->processor
+ : cpumask_cycle(vc->processor, &cpus);
+ ASSERT( !cpumask_empty(&cpus) && cpumask_test_cpu(cpu, &cpus) );
+
+ return cpu;
+}
+
+/*
+ * Burn budget in nanosecond granularity
+ */
+static void
+burn_budgets(const struct scheduler *ops, struct rt_vcpu *svc, s_time_t now)
+{
+ s_time_t delta;
+
+ /* don't burn budget for idle VCPU */
+ if ( is_idle_vcpu(svc->vcpu) )
+ return;
+
+ rt_update_helper(now, svc);
+
+ /* not burn budget when vcpu miss deadline */
+ if ( now >= svc->cur_deadline )
+ return;
+
+ /* burn at nanoseconds level */
+ delta = now - svc->last_start;
+ /*
+ * delta < 0 only happens in nested virtualization;
+ * TODO: how should we handle delta < 0 in a better way?
+ */
+ if ( delta < 0 )
+ {
+ printk("%s, ATTENTION: now is behind last_start! delta = %ld",
+ __func__, delta);
+ rt_dump_vcpu(ops, svc);
+ svc->last_start = now;
+ svc->cur_budget = 0;
+ return;
+ }
+
+ if ( svc->cur_budget == 0 )
+ return;
+
+ svc->cur_budget -= delta;
+ if ( svc->cur_budget < 0 )
+ svc->cur_budget = 0;
+
+ /* TRACE */
+ {
+ struct {
+ unsigned dom:16, vcpu:16;
+ unsigned cur_budget_lo;
+ unsigned cur_budget_hi;
+ int delta;
+ } d;
+ d.dom = svc->vcpu->domain->domain_id;
+ d.vcpu = svc->vcpu->vcpu_id;
+ d.cur_budget_lo = (unsigned) svc->cur_budget;
+ d.cur_budget_hi = (unsigned) (svc->cur_budget >> 32);
+ d.delta = delta;
+ trace_var(TRC_RT_BUDGET_BURN, 1,
+ sizeof(d),
+ (unsigned char *) &d);
+ }
+}
+
+/*
+ * RunQ is sorted. Pick first one within cpumask. If no one, return NULL
+ * lock is grabbed before calling this function
+ */
+static struct rt_vcpu *
+__runq_pick(const struct scheduler *ops, cpumask_t mask)
+{
+ struct list_head *runq = RUNQ(ops);
+ struct list_head *iter;
+ struct rt_vcpu *svc = NULL;
+ struct rt_vcpu *iter_svc = NULL;
+ cpumask_t cpu_common;
+ cpumask_t *online;
+ struct rt_private * prv = RT_PRIV(ops);
+
+ list_for_each(iter, runq)
+ {
+ iter_svc = __runq_elem(iter);
+
+ /* flag vcpu */
+ if(iter_svc->sdom == NULL)
+ break;
+
+ /* mask cpu_hard_affinity & cpupool & priv->cpus */
+ online = cpupool_scheduler_cpumask(iter_svc->vcpu->domain->cpupool);
+ cpumask_and(&cpu_common, online, &prv->cpus);
+ cpumask_and(&cpu_common, &cpu_common,
iter_svc->vcpu->cpu_hard_affinity);
+ cpumask_and(&cpu_common, &mask, &cpu_common);
+ if ( cpumask_empty(&cpu_common) )
+ continue;
+
+ ASSERT( iter_svc->cur_budget > 0 );
+
+ svc = iter_svc;
+ break;
+ }
+
+ /* TRACE */
+ {
+ if( svc != NULL )
+ {
+ struct {
+ unsigned dom:16, vcpu:16;
+ unsigned cur_deadline_lo, cur_deadline_hi;
+ unsigned cur_budget_lo, cur_budget_hi;
+ } d;
+ d.dom = svc->vcpu->domain->domain_id;
+ d.vcpu = svc->vcpu->vcpu_id;
+ d.cur_deadline_lo = (unsigned) svc->cur_deadline;
+ d.cur_deadline_hi = (unsigned) (svc->cur_deadline >> 32);
+ d.cur_budget_lo = (unsigned) svc->cur_budget;
+ d.cur_budget_hi = (unsigned) (svc->cur_budget >> 32);
+ trace_var(TRC_RT_RUNQ_PICK, 1,
+ sizeof(d),
+ (unsigned char *) &d);
+ }
+ else
+ trace_var(TRC_RT_RUNQ_PICK, 1, 0, NULL);
+ }
+
+ return svc;
+}
+
+/*
+ * Update vcpu's budget and sort runq by insert the modifed vcpu back to runq
+ * lock is grabbed before calling this function
+ */
+static void
+__repl_update(const struct scheduler *ops, s_time_t now)
+{
+ struct list_head *runq = RUNQ(ops);
+ struct list_head *iter;
+ struct list_head *tmp;
+ struct rt_vcpu *svc = NULL;
+
+ list_for_each_safe(iter, tmp, runq)
+ {
+ svc = __runq_elem(iter);
+
+ /* not update flag_vcpu's budget */
+ if(svc->sdom == NULL)
+ continue;
+
+ rt_update_helper(now, svc);
+ /* reinsert the vcpu if its deadline is updated */
+ if ( now >= 0 )
+ {
+ __runq_remove(svc);
+ __runq_insert(ops, svc);
+ }
+ }
+}
+
+/*
+ * schedule function for rt scheduler.
+ * The lock is already grabbed in schedule.c, no need to lock here
+ */
+static struct task_slice
+rt_schedule(const struct scheduler *ops, s_time_t now, bool_t
tasklet_work_scheduled)
+{
+ const int cpu = smp_processor_id();
+ struct rt_private * prv = RT_PRIV(ops);
+ struct rt_vcpu * const scurr = RT_VCPU(current);
+ struct rt_vcpu * snext = NULL;
+ struct task_slice ret = { .migrated = 0 };
+
+ /* clear ticked bit now that we've been scheduled */
+ if ( cpumask_test_cpu(cpu, &prv->tickled) )
+ cpumask_clear_cpu(cpu, &prv->tickled);
+
+ /* burn_budget would return for IDLE VCPU */
+ burn_budgets(ops, scurr, now);
+
+ __repl_update(ops, now);
+
+ if ( tasklet_work_scheduled )
+ {
+ snext = RT_VCPU(idle_vcpu[cpu]);
+ }
+ else
+ {
+ cpumask_t cur_cpu;
+ cpumask_clear(&cur_cpu);
+ cpumask_set_cpu(cpu, &cur_cpu);
+ snext = __runq_pick(ops, cur_cpu);
+ if ( snext == NULL )
+ snext = RT_VCPU(idle_vcpu[cpu]);
+
+ /* if scurr has higher priority and budget, still pick scurr */
+ if ( !is_idle_vcpu(current) &&
+ vcpu_runnable(current) &&
+ scurr->cur_budget > 0 &&
+ ( is_idle_vcpu(snext->vcpu) ||
+ scurr->cur_deadline <= snext->cur_deadline ) )
+ snext = scurr;
+ }
+
+ if ( snext != scurr &&
+ !is_idle_vcpu(current) &&
+ vcpu_runnable(current) )
+ set_bit(__RT_delayed_runq_add, &scurr->flags);
+
+
+ snext->last_start = now;
+ if ( !is_idle_vcpu(snext->vcpu) )
+ {
+ if ( snext != scurr )
+ {
+ __runq_remove(snext);
+ set_bit(__RT_scheduled, &snext->flags);
+ }
+ if ( snext->vcpu->processor != cpu )
+ {
+ snext->vcpu->processor = cpu;
+ ret.migrated = 1;
+ }
+ }
+
+ ret.time = MILLISECS(1); /* sched quantum */
+ ret.task = snext->vcpu;
+
+ /* TRACE */
+ {
+ struct {
+ unsigned dom:16,vcpu:16;
+ unsigned cur_deadline_lo, cur_deadline_hi;
+ unsigned cur_budget_lo, cur_budget_hi;
+ } d;
+ d.dom = snext->vcpu->domain->domain_id;
+ d.vcpu = snext->vcpu->vcpu_id;
+ d.cur_deadline_lo = (unsigned) snext->cur_deadline;
+ d.cur_deadline_hi = (unsigned) (snext->cur_deadline >> 32);
+ d.cur_budget_lo = (unsigned) snext->cur_budget;
+ d.cur_budget_hi = (unsigned) (snext->cur_budget >> 32);
+ trace_var(TRC_RT_SCHED_TASKLET, 1,
+ sizeof(d),
+ (unsigned char *)&d);
+ }
+
+ return ret;
+}
+
+/*
+ * Remove VCPU from RunQ
+ * The lock is already grabbed in schedule.c, no need to lock here
+ */
+static void
+rt_vcpu_sleep(const struct scheduler *ops, struct vcpu *vc)
+{
+ struct rt_vcpu * const svc = RT_VCPU(vc);
+
+ BUG_ON( is_idle_vcpu(vc) );
+
+ if ( curr_on_cpu(vc->processor) == vc )
+ cpu_raise_softirq(vc->processor, SCHEDULE_SOFTIRQ);
+ else if ( __vcpu_on_runq(svc) )
+ __runq_remove(svc);
+ else if ( test_bit(__RT_delayed_runq_add, &svc->flags) )
+ clear_bit(__RT_delayed_runq_add, &svc->flags);
+}
+
+/*
+ * Pick a vcpu on a cpu to kick out to place the running candidate
+ * Called by wake() and context_saved()
+ * We have a running candidate here, the kick logic is:
+ * Among all the cpus that are within the cpu affinity
+ * 1) if the new->cpu is idle, kick it. This could benefit cache hit
+ * 2) if there are any idle vcpu, kick it.
+ * 3) now all pcpus are busy, among all the running vcpus, pick lowest
priority one
+ * if snext has higher priority, kick it.
+ *
+ * TODO:
+ * 1) what if these two vcpus belongs to the same domain?
+ * replace a vcpu belonging to the same domain introduces more overhead
+ *
+ * lock is grabbed before calling this function
+ */
+static void
+runq_tickle(const struct scheduler *ops, struct rt_vcpu *new)
+{
+ struct rt_private * prv = RT_PRIV(ops);
+ struct rt_vcpu * latest_deadline_vcpu = NULL; /* lowest priority
scheduled */
+ struct rt_vcpu * iter_svc;
+ struct vcpu * iter_vc;
+ int cpu = 0, cpu_to_tickle = 0;
+ cpumask_t not_tickled;
+ cpumask_t *online;
+
+ if ( new == NULL || is_idle_vcpu(new->vcpu) )
+ return;
+
+ online = cpupool_scheduler_cpumask(new->vcpu->domain->cpupool);
+ cpumask_and(¬_tickled, online, &prv->cpus);
+ cpumask_and(¬_tickled, ¬_tickled, new->vcpu->cpu_hard_affinity);
+ cpumask_andnot(¬_tickled, ¬_tickled, &prv->tickled);
+
+ /* 1) if new's previous cpu is idle, kick it for cache benefit */
+ if ( is_idle_vcpu(curr_on_cpu(new->vcpu->processor)) )
+ {
+ cpu_to_tickle = new->vcpu->processor;
+ goto out;
+ }
+
+ /* 2) if there are any idle pcpu, kick it */
+ /* The same loop also find the one with lowest priority */
+ for_each_cpu(cpu, ¬_tickled)
+ {
+ iter_vc = curr_on_cpu(cpu);
+ if ( is_idle_vcpu(iter_vc) )
+ {
+ cpu_to_tickle = cpu;
+ goto out;
+ }
+ iter_svc = RT_VCPU(iter_vc);
+ if ( latest_deadline_vcpu == NULL ||
+ iter_svc->cur_deadline > latest_deadline_vcpu->cur_deadline )
+ latest_deadline_vcpu = iter_svc;
+ }
+
+ /* 3) candicate has higher priority, kick out the lowest priority vcpu */
+ if ( latest_deadline_vcpu != NULL && new->cur_deadline <
latest_deadline_vcpu->cur_deadline )
+ {
+ cpu_to_tickle = latest_deadline_vcpu->vcpu->processor;
+ goto out;
+ }
+
+out:
+ /* TRACE */
+ {
+ struct {
+ unsigned cpu:8, pad:24;
+ } d;
+ d.cpu = cpu_to_tickle;
+ d.pad = 0;
+ trace_var(TRC_RT_TICKLE, 0,
+ sizeof(d),
+ (unsigned char *)&d);
+ }
+
+ cpumask_set_cpu(cpu_to_tickle, &prv->tickled);
+ cpu_raise_softirq(cpu_to_tickle, SCHEDULE_SOFTIRQ);
+ return;
+}
+
+/*
+ * Should always wake up runnable vcpu, put it back to RunQ.
+ * Check priority to raise interrupt
+ * The lock is already grabbed in schedule.c, no need to lock here
+ * TODO: what if these two vcpus belongs to the same domain?
+ */
+static void
+rt_vcpu_wake(const struct scheduler *ops, struct vcpu *vc)
+{
+ struct rt_vcpu * const svc = RT_VCPU(vc);
+ s_time_t now = NOW();
+ struct rt_private * prv = RT_PRIV(ops);
+ struct rt_vcpu * snext = NULL; /* highest priority on RunQ */
+
+ BUG_ON( is_idle_vcpu(vc) );
+
+ if ( unlikely(curr_on_cpu(vc->processor) == vc) )
+ return;
+
+ /* on RunQ, just update info is ok */
+ if ( unlikely(__vcpu_on_runq(svc)) )
+ return;
+
+ /* If context hasn't been saved for this vcpu yet, we can't put it on
+ * the Runqueue. Instead, we set a flag so that it will be put on the
Runqueue
+ * After the context has been saved.
+ */
+ if ( unlikely(test_bit(__RT_scheduled, &svc->flags)) )
+ {
+ set_bit(__RT_delayed_runq_add, &svc->flags);
+ return;
+ }
+
+ rt_update_helper(now, svc);
+
+ __runq_insert(ops, svc);
+ __repl_update(ops, now);
+ snext = __runq_pick(ops, prv->cpus); /* pick snext from ALL valid cpus
*/
+ runq_tickle(ops, snext);
+
+ return;
+}
+
+/*
+ * scurr has finished context switch, insert it back to the RunQ,
+ * and then pick the highest priority vcpu from runq to run
+ */
+static void
+rt_context_saved(const struct scheduler *ops, struct vcpu *vc)
+{
+ struct rt_vcpu * svc = RT_VCPU(vc);
+ struct rt_vcpu * snext = NULL;
+ struct rt_private * prv = RT_PRIV(ops);
+ spinlock_t *lock = vcpu_schedule_lock_irq(vc);
+
+ clear_bit(__RT_scheduled, &svc->flags);
+ /* not insert idle vcpu to runq */
+ if ( is_idle_vcpu(vc) )
+ goto out;
+
+ if ( test_and_clear_bit(__RT_delayed_runq_add, &svc->flags) &&
+ likely(vcpu_runnable(vc)) )
+ {
+ __runq_insert(ops, svc);
+ __repl_update(ops, NOW());
+ snext = __runq_pick(ops, prv->cpus); /* pick snext from ALL cpus */
+ runq_tickle(ops, snext);
+ }
+out:
+ vcpu_schedule_unlock_irq(lock, vc);
+}
+
+/*
+ * set/get each vcpu info of each domain
+ */
+static int
+rt_dom_cntl(
+ const struct scheduler *ops,
+ struct domain *d,
+ struct xen_domctl_scheduler_op *op)
+{
+ struct rt_dom * const sdom = RT_DOM(d);
+ struct rt_vcpu * svc;
+ struct list_head *iter;
+ int rc = 0;
+
+ switch ( op->cmd )
+ {
+ case XEN_DOMCTL_SCHEDOP_getinfo:
+ /* for debug use, whenever adjust Dom0 parameter, do global dump */
+ if ( d->domain_id == 0 )
+ rt_dump(ops);
+
+ svc = list_entry(sdom->vcpu.next, struct rt_vcpu, sdom_elem);
+ op->u.rt.period = svc->period / MICROSECS(1); /* transfer to us */
+ op->u.rt.budget = svc->budget / MICROSECS(1);
+ break;
+ case XEN_DOMCTL_SCHEDOP_putinfo:
+ list_for_each( iter, &sdom->vcpu )
+ {
+ struct rt_vcpu * svc = list_entry(iter, struct rt_vcpu, sdom_elem);
+ svc->period = MICROSECS(op->u.rt.period); /* transfer to nanosec */
+ svc->budget = MICROSECS(op->u.rt.budget);
+ }
+ break;
+ }
+
+ return rc;
+}
+
+static struct rt_private _rt_priv;
+
+const struct scheduler sched_rt_ds_def = {
+ .name = "SMP RT DS Scheduler",
+ .opt_name = "rt_ds",
+ .sched_id = XEN_SCHEDULER_RT_DS,
+ .sched_data = &_rt_priv,
+
+ .dump_cpu_state = rt_dump_pcpu,
+ .dump_settings = rt_dump,
+ .init = rt_init,
+ .deinit = rt_deinit,
+ .alloc_pdata = rt_alloc_pdata,
+ .free_pdata = rt_free_pdata,
+ .alloc_domdata = rt_alloc_domdata,
+ .free_domdata = rt_free_domdata,
+ .init_domain = rt_dom_init,
+ .destroy_domain = rt_dom_destroy,
+ .alloc_vdata = rt_alloc_vdata,
+ .free_vdata = rt_free_vdata,
+ .insert_vcpu = rt_vcpu_insert,
+ .remove_vcpu = rt_vcpu_remove,
+
+ .adjust = rt_dom_cntl,
+
+ .pick_cpu = rt_cpu_pick,
+ .do_schedule = rt_schedule,
+ .sleep = rt_vcpu_sleep,
+ .wake = rt_vcpu_wake,
+ .context_saved = rt_context_saved,
+};
diff --git a/xen/common/schedule.c b/xen/common/schedule.c
index 73cc2ea..dc4f749 100644
--- a/xen/common/schedule.c
+++ b/xen/common/schedule.c
@@ -69,6 +69,7 @@ static const struct scheduler *schedulers[] = {
&sched_credit_def,
&sched_credit2_def,
&sched_arinc653_def,
+ &sched_rt_ds_def,
};
static struct scheduler __read_mostly ops;
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 69a8b44..11654d0 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -347,6 +347,8 @@ DEFINE_XEN_GUEST_HANDLE(xen_domctl_max_vcpus_t);
#define XEN_SCHEDULER_CREDIT 5
#define XEN_SCHEDULER_CREDIT2 6
#define XEN_SCHEDULER_ARINC653 7
+#define XEN_SCHEDULER_RT_DS 8
+
/* Set or get info? */
#define XEN_DOMCTL_SCHEDOP_putinfo 0
#define XEN_DOMCTL_SCHEDOP_getinfo 1
@@ -368,6 +370,10 @@ struct xen_domctl_scheduler_op {
struct xen_domctl_sched_credit2 {
uint16_t weight;
} credit2;
+ struct xen_domctl_sched_rt{
+ uint32_t period;
+ uint32_t budget;
+ } rt;
} u;
};
typedef struct xen_domctl_scheduler_op xen_domctl_scheduler_op_t;
diff --git a/xen/include/public/trace.h b/xen/include/public/trace.h
index cfcf4aa..87340c4 100644
--- a/xen/include/public/trace.h
+++ b/xen/include/public/trace.h
@@ -77,6 +77,7 @@
#define TRC_SCHED_CSCHED2 1
#define TRC_SCHED_SEDF 2
#define TRC_SCHED_ARINC653 3
+#define TRC_SCHED_RT 4
/* Per-scheduler tracing */
#define TRC_SCHED_CLASS_EVT(_c, _e) \
diff --git a/xen/include/xen/sched-if.h b/xen/include/xen/sched-if.h
index 4164dff..04d81dc 100644
--- a/xen/include/xen/sched-if.h
+++ b/xen/include/xen/sched-if.h
@@ -169,6 +169,7 @@ extern const struct scheduler sched_sedf_def;
extern const struct scheduler sched_credit_def;
extern const struct scheduler sched_credit2_def;
extern const struct scheduler sched_arinc653_def;
+extern const struct scheduler sched_rt_ds_def;
struct cpupool
--
1.7.9.5
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