blob: bf652cd77000e01c06ba723ae22f8a7e3aefe61c [file] [log] [blame]
/* sched.c - SPU scheduler.
*
* Copyright (C) IBM 2005
* Author: Mark Nutter <mnutter@us.ibm.com>
*
* SPU scheduler, based on Linux thread priority. For now use
* a simple "cooperative" yield model with no preemption. SPU
* scheduling will eventually be preemptive: When a thread with
* a higher static priority gets ready to run, then an active SPU
* context will be preempted and returned to the waitq.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#undef DEBUG
#include <linux/config.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/completion.h>
#include <linux/vmalloc.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/spu.h>
#include <asm/spu_csa.h>
#include "spufs.h"
#define SPU_MIN_TIMESLICE (100 * HZ / 1000)
#define SPU_BITMAP_SIZE (((MAX_PRIO+BITS_PER_LONG)/BITS_PER_LONG)+1)
struct spu_prio_array {
atomic_t nr_blocked;
unsigned long bitmap[SPU_BITMAP_SIZE];
wait_queue_head_t waitq[MAX_PRIO];
};
/* spu_runqueue - This is the main runqueue data structure for SPUs. */
struct spu_runqueue {
struct semaphore sem;
unsigned long nr_active;
unsigned long nr_idle;
unsigned long nr_switches;
struct list_head active_list;
struct list_head idle_list;
struct spu_prio_array prio;
};
static struct spu_runqueue *spu_runqueues = NULL;
static inline struct spu_runqueue *spu_rq(void)
{
/* Future: make this a per-NODE array,
* and use cpu_to_node(smp_processor_id())
*/
return spu_runqueues;
}
static inline struct spu *del_idle(struct spu_runqueue *rq)
{
struct spu *spu;
BUG_ON(rq->nr_idle <= 0);
BUG_ON(list_empty(&rq->idle_list));
/* Future: Move SPU out of low-power SRI state. */
spu = list_entry(rq->idle_list.next, struct spu, sched_list);
list_del_init(&spu->sched_list);
rq->nr_idle--;
return spu;
}
static inline void del_active(struct spu_runqueue *rq, struct spu *spu)
{
BUG_ON(rq->nr_active <= 0);
BUG_ON(list_empty(&rq->active_list));
list_del_init(&spu->sched_list);
rq->nr_active--;
}
static inline void add_idle(struct spu_runqueue *rq, struct spu *spu)
{
/* Future: Put SPU into low-power SRI state. */
list_add_tail(&spu->sched_list, &rq->idle_list);
rq->nr_idle++;
}
static inline void add_active(struct spu_runqueue *rq, struct spu *spu)
{
rq->nr_active++;
rq->nr_switches++;
list_add_tail(&spu->sched_list, &rq->active_list);
}
static void prio_wakeup(struct spu_runqueue *rq)
{
if (atomic_read(&rq->prio.nr_blocked) && rq->nr_idle) {
int best = sched_find_first_bit(rq->prio.bitmap);
if (best < MAX_PRIO) {
wait_queue_head_t *wq = &rq->prio.waitq[best];
wake_up_interruptible_nr(wq, 1);
}
}
}
static void prio_wait(struct spu_runqueue *rq, struct spu_context *ctx,
u64 flags)
{
int prio = current->prio;
wait_queue_head_t *wq = &rq->prio.waitq[prio];
DEFINE_WAIT(wait);
__set_bit(prio, rq->prio.bitmap);
atomic_inc(&rq->prio.nr_blocked);
prepare_to_wait_exclusive(wq, &wait, TASK_INTERRUPTIBLE);
if (!signal_pending(current)) {
up(&rq->sem);
up_write(&ctx->state_sema);
pr_debug("%s: pid=%d prio=%d\n", __FUNCTION__,
current->pid, current->prio);
schedule();
down_write(&ctx->state_sema);
down(&rq->sem);
}
finish_wait(wq, &wait);
atomic_dec(&rq->prio.nr_blocked);
if (!waitqueue_active(wq))
__clear_bit(prio, rq->prio.bitmap);
}
static inline int is_best_prio(struct spu_runqueue *rq)
{
int best_prio;
best_prio = sched_find_first_bit(rq->prio.bitmap);
return (current->prio < best_prio) ? 1 : 0;
}
static inline void mm_needs_global_tlbie(struct mm_struct *mm)
{
/* Global TLBIE broadcast required with SPEs. */
#if (NR_CPUS > 1)
__cpus_setall(&mm->cpu_vm_mask, NR_CPUS);
#else
__cpus_setall(&mm->cpu_vm_mask, NR_CPUS+1); /* is this ok? */
#endif
}
static inline void bind_context(struct spu *spu, struct spu_context *ctx)
{
pr_debug("%s: pid=%d SPU=%d\n", __FUNCTION__, current->pid,
spu->number);
spu->ctx = ctx;
spu->flags = 0;
ctx->flags = 0;
ctx->spu = spu;
ctx->ops = &spu_hw_ops;
spu->pid = current->pid;
spu->prio = current->prio;
spu->mm = ctx->owner;
mm_needs_global_tlbie(spu->mm);
spu->ibox_callback = spufs_ibox_callback;
spu->wbox_callback = spufs_wbox_callback;
spu->stop_callback = spufs_stop_callback;
spu->mfc_callback = spufs_mfc_callback;
mb();
spu_unmap_mappings(ctx);
spu_restore(&ctx->csa, spu);
spu->timestamp = jiffies;
}
static inline void unbind_context(struct spu *spu, struct spu_context *ctx)
{
pr_debug("%s: unbind pid=%d SPU=%d\n", __FUNCTION__,
spu->pid, spu->number);
spu_unmap_mappings(ctx);
spu_save(&ctx->csa, spu);
spu->timestamp = jiffies;
ctx->state = SPU_STATE_SAVED;
spu->ibox_callback = NULL;
spu->wbox_callback = NULL;
spu->stop_callback = NULL;
spu->mfc_callback = NULL;
spu->mm = NULL;
spu->pid = 0;
spu->prio = MAX_PRIO;
ctx->ops = &spu_backing_ops;
ctx->spu = NULL;
ctx->flags = 0;
spu->flags = 0;
spu->ctx = NULL;
}
static void spu_reaper(void *data)
{
struct spu_context *ctx = data;
struct spu *spu;
down_write(&ctx->state_sema);
spu = ctx->spu;
if (spu && test_bit(SPU_CONTEXT_PREEMPT, &ctx->flags)) {
if (atomic_read(&spu->rq->prio.nr_blocked)) {
pr_debug("%s: spu=%d\n", __func__, spu->number);
ctx->ops->runcntl_stop(ctx);
spu_deactivate(ctx);
wake_up_all(&ctx->stop_wq);
} else {
clear_bit(SPU_CONTEXT_PREEMPT, &ctx->flags);
}
}
up_write(&ctx->state_sema);
put_spu_context(ctx);
}
static void schedule_spu_reaper(struct spu_runqueue *rq, struct spu *spu)
{
struct spu_context *ctx = get_spu_context(spu->ctx);
unsigned long now = jiffies;
unsigned long expire = spu->timestamp + SPU_MIN_TIMESLICE;
set_bit(SPU_CONTEXT_PREEMPT, &ctx->flags);
INIT_WORK(&ctx->reap_work, spu_reaper, ctx);
if (time_after(now, expire))
schedule_work(&ctx->reap_work);
else
schedule_delayed_work(&ctx->reap_work, expire - now);
}
static void check_preempt_active(struct spu_runqueue *rq)
{
struct list_head *p;
struct spu *worst = NULL;
list_for_each(p, &rq->active_list) {
struct spu *spu = list_entry(p, struct spu, sched_list);
struct spu_context *ctx = spu->ctx;
if (!test_bit(SPU_CONTEXT_PREEMPT, &ctx->flags)) {
if (!worst || (spu->prio > worst->prio)) {
worst = spu;
}
}
}
if (worst && (current->prio < worst->prio))
schedule_spu_reaper(rq, worst);
}
static struct spu *get_idle_spu(struct spu_context *ctx, u64 flags)
{
struct spu_runqueue *rq;
struct spu *spu = NULL;
rq = spu_rq();
down(&rq->sem);
for (;;) {
if (rq->nr_idle > 0) {
if (is_best_prio(rq)) {
/* Fall through. */
spu = del_idle(rq);
break;
} else {
prio_wakeup(rq);
up(&rq->sem);
yield();
if (signal_pending(current)) {
return NULL;
}
rq = spu_rq();
down(&rq->sem);
continue;
}
} else {
check_preempt_active(rq);
prio_wait(rq, ctx, flags);
if (signal_pending(current)) {
prio_wakeup(rq);
spu = NULL;
break;
}
continue;
}
}
up(&rq->sem);
return spu;
}
static void put_idle_spu(struct spu *spu)
{
struct spu_runqueue *rq = spu->rq;
down(&rq->sem);
add_idle(rq, spu);
prio_wakeup(rq);
up(&rq->sem);
}
static int get_active_spu(struct spu *spu)
{
struct spu_runqueue *rq = spu->rq;
struct list_head *p;
struct spu *tmp;
int rc = 0;
down(&rq->sem);
list_for_each(p, &rq->active_list) {
tmp = list_entry(p, struct spu, sched_list);
if (tmp == spu) {
del_active(rq, spu);
rc = 1;
break;
}
}
up(&rq->sem);
return rc;
}
static void put_active_spu(struct spu *spu)
{
struct spu_runqueue *rq = spu->rq;
down(&rq->sem);
add_active(rq, spu);
up(&rq->sem);
}
/* Lock order:
* spu_activate() & spu_deactivate() require the
* caller to have down_write(&ctx->state_sema).
*
* The rq->sem is breifly held (inside or outside a
* given ctx lock) for list management, but is never
* held during save/restore.
*/
int spu_activate(struct spu_context *ctx, u64 flags)
{
struct spu *spu;
if (ctx->spu)
return 0;
spu = get_idle_spu(ctx, flags);
if (!spu)
return (signal_pending(current)) ? -ERESTARTSYS : -EAGAIN;
bind_context(spu, ctx);
/*
* We're likely to wait for interrupts on the same
* CPU that we are now on, so send them here.
*/
spu_irq_setaffinity(spu, raw_smp_processor_id());
put_active_spu(spu);
return 0;
}
void spu_deactivate(struct spu_context *ctx)
{
struct spu *spu;
int needs_idle;
spu = ctx->spu;
if (!spu)
return;
needs_idle = get_active_spu(spu);
unbind_context(spu, ctx);
if (needs_idle)
put_idle_spu(spu);
}
void spu_yield(struct spu_context *ctx)
{
struct spu *spu;
int need_yield = 0;
down_write(&ctx->state_sema);
spu = ctx->spu;
if (spu && (sched_find_first_bit(spu->rq->prio.bitmap) < MAX_PRIO)) {
pr_debug("%s: yielding SPU %d\n", __FUNCTION__, spu->number);
spu_deactivate(ctx);
ctx->state = SPU_STATE_SAVED;
need_yield = 1;
} else if (spu) {
spu->prio = MAX_PRIO;
}
up_write(&ctx->state_sema);
if (unlikely(need_yield))
yield();
}
int __init spu_sched_init(void)
{
struct spu_runqueue *rq;
struct spu *spu;
int i;
rq = spu_runqueues = kmalloc(sizeof(struct spu_runqueue), GFP_KERNEL);
if (!rq) {
printk(KERN_WARNING "%s: Unable to allocate runqueues.\n",
__FUNCTION__);
return 1;
}
memset(rq, 0, sizeof(struct spu_runqueue));
init_MUTEX(&rq->sem);
INIT_LIST_HEAD(&rq->active_list);
INIT_LIST_HEAD(&rq->idle_list);
rq->nr_active = 0;
rq->nr_idle = 0;
rq->nr_switches = 0;
atomic_set(&rq->prio.nr_blocked, 0);
for (i = 0; i < MAX_PRIO; i++) {
init_waitqueue_head(&rq->prio.waitq[i]);
__clear_bit(i, rq->prio.bitmap);
}
__set_bit(MAX_PRIO, rq->prio.bitmap);
for (;;) {
spu = spu_alloc();
if (!spu)
break;
pr_debug("%s: adding SPU[%d]\n", __FUNCTION__, spu->number);
add_idle(rq, spu);
spu->rq = rq;
spu->timestamp = jiffies;
}
if (!rq->nr_idle) {
printk(KERN_WARNING "%s: No available SPUs.\n", __FUNCTION__);
kfree(rq);
return 1;
}
return 0;
}
void __exit spu_sched_exit(void)
{
struct spu_runqueue *rq = spu_rq();
struct spu *spu;
if (!rq) {
printk(KERN_WARNING "%s: no runqueues!\n", __FUNCTION__);
return;
}
while (rq->nr_idle > 0) {
spu = del_idle(rq);
if (!spu)
break;
spu_free(spu);
}
kfree(rq);
}