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/****************************************************************************
* Round Robin Scheduler for Xen
*
* by Mark Williamson (C) 2004 Intel Research Cambridge
*/
#include <xen/sched.h>
#include <xen/sched-if.h>
#include <hypervisor-ifs/sched_ctl.h>
#include <xen/ac_timer.h>
#include <xen/softirq.h>
#include <xen/time.h>
#include <xen/slab.h>
#define TIME_SLOP (s32)MICROSECS(50) /* allow time to slip a bit */
static s_time_t rr_slice = MILLISECS(10);
/* Only runqueue pointers and domain pointer*/
struct rrobin_dom_info
{
struct list_head run_list;
struct domain *domain;
};
static spinlock_t run_locks[NR_CPUS];
#define RR_INFO(d) ((struct rrobin_dom_info *)d->sched_priv)
#define RUNLIST(d) ((struct list_head *)&(RR_INFO(d)->run_list))
#define RUNQUEUE(cpu) RUNLIST(schedule_data[cpu].idle)
/* SLAB cache for struct rrobin_dom_info objects */
static xmem_cache_t *dom_info_cache;
/*
* Wrappers for run-queue management. Must be called with the run_lock
* held.
*/
static inline void __add_to_runqueue_head(struct domain *d)
{
list_add(RUNLIST(d), RUNQUEUE(d->processor));
}
static inline void __add_to_runqueue_tail(struct domain *d)
{
list_add_tail(RUNLIST(d), RUNQUEUE(d->processor));
}
static inline void __del_from_runqueue(struct domain *d)
{
struct list_head *runlist = RUNLIST(d);
list_del(runlist);
runlist->next = NULL;
}
static inline int __task_on_runqueue(struct domain *d)
{
return (RUNLIST(d))->next != NULL;
}
/* Ensures proper initialisation of the dom_info */
static void cache_constructor(void *arg1, xmem_cache_t *arg2, unsigned long arg3)
{
struct rrobin_dom_info *dom_inf = (struct rrobin_dom_info*)arg1;
dom_inf->run_list.next = NULL;
dom_inf->run_list.prev = NULL;
}
/* Initialises the runqueues and creates the domain info cache */
static int rr_init_scheduler()
{
int i;
for ( i = 0; i < NR_CPUS; i++ )
{
INIT_LIST_HEAD(RUNQUEUE(i));
spin_lock_init(&run_locks[i]);
}
dom_info_cache = xmem_cache_create("FBVT dom info",
sizeof(struct rrobin_dom_info),
0, 0, cache_constructor, NULL);
if(dom_info_cache == NULL)
{
printk("Could not allocate SLAB cache.\n");
return -1;
}
return 0;
}
/* Allocates memory for per domain private scheduling data*/
static int rr_alloc_task(struct domain *d)
{
d->sched_priv = xmem_cache_alloc(dom_info_cache);
if ( d->sched_priv == NULL )
return -1;
return 0;
}
/* Setup the rr_dom_info */
static void rr_add_task(struct domain *p)
{
struct rrobin_dom_info *inf;
RR_INFO(p)->domain = p;
inf = RR_INFO(p);
}
/* Frees memory used by domain info */
static void rr_free_task(struct domain *p)
{
ASSERT( p->sched_priv != NULL );
xmem_cache_free( dom_info_cache, p->sched_priv );
}
/* Initialises idle task */
static int rr_init_idle_task(struct domain *p)
{
unsigned long flags;
if(rr_alloc_task(p) < 0) return -1;
rr_add_task(p);
spin_lock_irqsave(&run_locks[p->processor], flags);
set_bit(DF_RUNNING, &p->flags);
if ( !__task_on_runqueue(p) )
__add_to_runqueue_head(p);
spin_unlock_irqrestore(&run_locks[p->processor], flags);
return 0;
}
/* Main scheduling function */
static task_slice_t rr_do_schedule(s_time_t now)
{
unsigned long flags;
struct domain *prev = current;
int cpu = current->processor;
task_slice_t ret;
spin_lock_irqsave(&run_locks[cpu], flags);
if(!is_idle_task(prev))
{
__del_from_runqueue(prev);
if ( domain_runnable(prev) )
__add_to_runqueue_tail(prev);
}
spin_unlock_irqrestore(&run_locks[cpu], flags);
ret.task = list_entry( RUNQUEUE(cpu)->next,
struct rrobin_dom_info,
run_list)->domain;
ret.time = rr_slice;
return ret;
}
/* Set/retrive control parameter(s) */
static int rr_ctl(struct sched_ctl_cmd *cmd)
{
if ( cmd->direction == SCHED_INFO_PUT )
{
rr_slice = cmd->u.rrobin.slice;
}
else /* cmd->direction == SCHED_INFO_GET */
{
cmd->u.rrobin.slice = rr_slice;
}
return 0;
}
static void rr_dump_settings()
{
printk("rr_slice = %llu ", rr_slice);
}
static void rr_sleep(struct domain *d)
{
unsigned long flags;
if ( test_bit(DF_RUNNING, &d->flags) )
cpu_raise_softirq(d->processor, SCHEDULE_SOFTIRQ);
else
{
spin_lock_irqsave(&run_locks[d->processor], flags);
if ( __task_on_runqueue(d) )
__del_from_runqueue(d);
spin_unlock_irqrestore(&run_locks[d->processor], flags);
}
}
void rr_wake(struct domain *d)
{
unsigned long flags;
struct domain *curr;
s_time_t now;
int cpu = d->processor;
spin_lock_irqsave(&run_locks[cpu], flags);
/* If on the runqueue already then someone has done the wakeup work. */
if ( unlikely(__task_on_runqueue(d)))
{
spin_unlock_irqrestore(&run_locks[cpu], flags);
return;
}
__add_to_runqueue_head(d);
spin_unlock_irqrestore(&run_locks[cpu], flags);
now = NOW();
spin_lock_irqsave(&schedule_data[cpu].schedule_lock, flags);
curr = schedule_data[cpu].curr;
if ( is_idle_task(curr) )
cpu_raise_softirq(cpu, SCHEDULE_SOFTIRQ);
spin_unlock_irqrestore(&schedule_data[cpu].schedule_lock, flags);
}
static void rr_dump_domain(struct domain *d)
{
printk("%u has=%c ", d->domain,
test_bit(DF_RUNNING, &d->flags) ? 'T':'F');
printk("c=0x%X%08X\n", (u32)(d->cpu_time>>32), (u32)d->cpu_time);
}
static void rr_dump_cpu_state(int i)
{
unsigned long flags;
struct list_head *list, *queue;
int loop = 0;
struct rrobin_dom_info *d_inf;
spin_lock_irqsave(&run_locks[i], flags);
queue = RUNQUEUE(i);
printk("QUEUE rq %lx n: %lx, p: %lx\n", (unsigned long)queue,
(unsigned long) queue->next, (unsigned long) queue->prev);
printk("%3d: ",loop++);
d_inf = list_entry(queue, struct rrobin_dom_info, run_list);
rr_dump_domain(d_inf->domain);
list_for_each ( list, queue )
{
printk("%3d: ",loop++);
d_inf = list_entry(list, struct rrobin_dom_info, run_list);
rr_dump_domain(d_inf->domain);
}
spin_unlock_irqrestore(&run_locks[i], flags);
}
struct scheduler sched_rrobin_def = {
.name = "Round-Robin Scheduler",
.opt_name = "rrobin",
.sched_id = SCHED_RROBIN,
.init_idle_task = rr_init_idle_task,
.alloc_task = rr_alloc_task,
.add_task = rr_add_task,
.free_task = rr_free_task,
.init_scheduler = rr_init_scheduler,
.do_schedule = rr_do_schedule,
.control = rr_ctl,
.dump_settings = rr_dump_settings,
.dump_cpu_state = rr_dump_cpu_state,
.sleep = rr_sleep,
.wake = rr_wake,
};
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