arch/powerpc/platforms/cell/spufs/sched.c

Source file repositories/reference/linux-study-clean/arch/powerpc/platforms/cell/spufs/sched.c

File Facts

System
Linux kernel
Corpus path
arch/powerpc/platforms/cell/spufs/sched.c
Extension
.c
Size
29112 bytes
Lines
1142
Domain
Architecture Layer
Bucket
arch/powerpc
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

struct spu_prio_array {
	DECLARE_BITMAP(bitmap, MAX_PRIO);
	struct list_head runq[MAX_PRIO];
	spinlock_t runq_lock;
	int nr_waiting;
};

static unsigned long spu_avenrun[3];
static struct spu_prio_array *spu_prio;
static struct task_struct *spusched_task;
static struct timer_list spusched_timer;
static struct timer_list spuloadavg_timer;

/*
 * Priority of a normal, non-rt, non-niced'd process (aka nice level 0).
 */
#define NORMAL_PRIO		120

/*
 * Frequency of the spu scheduler tick.  By default we do one SPU scheduler
 * tick for every 10 CPU scheduler ticks.
 */
#define SPUSCHED_TICK		(10)

/*
 * These are the 'tuning knobs' of the scheduler:
 *
 * Minimum timeslice is 5 msecs (or 1 spu scheduler tick, whichever is
 * larger), default timeslice is 100 msecs, maximum timeslice is 800 msecs.
 */
#define MIN_SPU_TIMESLICE	max(5 * HZ / (1000 * SPUSCHED_TICK), 1)
#define DEF_SPU_TIMESLICE	(100 * HZ / (1000 * SPUSCHED_TICK))

#define SCALE_PRIO(x, prio) \
	max(x * (MAX_PRIO - prio) / (NICE_WIDTH / 2), MIN_SPU_TIMESLICE)

/*
 * scale user-nice values [ -20 ... 0 ... 19 ] to time slice values:
 * [800ms ... 100ms ... 5ms]
 *
 * The higher a thread's priority, the bigger timeslices
 * it gets during one round of execution. But even the lowest
 * priority thread gets MIN_TIMESLICE worth of execution time.
 */
void spu_set_timeslice(struct spu_context *ctx)
{
	if (ctx->prio < NORMAL_PRIO)
		ctx->time_slice = SCALE_PRIO(DEF_SPU_TIMESLICE * 4, ctx->prio);
	else
		ctx->time_slice = SCALE_PRIO(DEF_SPU_TIMESLICE, ctx->prio);
}

/*
 * Update scheduling information from the owning thread.
 */
void __spu_update_sched_info(struct spu_context *ctx)
{
	/*
	 * assert that the context is not on the runqueue, so it is safe
	 * to change its scheduling parameters.
	 */
	BUG_ON(!list_empty(&ctx->rq));

	/*
	 * 32-Bit assignments are atomic on powerpc, and we don't care about
	 * memory ordering here because retrieving the controlling thread is
	 * per definition racy.
	 */
	ctx->tid = current->pid;

	/*
	 * We do our own priority calculations, so we normally want
	 * ->static_prio to start with. Unfortunately this field
	 * contains junk for threads with a realtime scheduling
	 * policy so we have to look at ->prio in this case.
	 */
	if (rt_prio(current->prio))
		ctx->prio = current->prio;
	else
		ctx->prio = current->static_prio;
	ctx->policy = current->policy;

	/*
	 * TO DO: the context may be loaded, so we may need to activate
	 * it again on a different node. But it shouldn't hurt anything
	 * to update its parameters, because we know that the scheduler
	 * is not actively looking at this field, since it is not on the
	 * runqueue. The context will be rescheduled on the proper node
	 * if it is timesliced or preempted.
	 */

Annotation

Implementation Notes