// SPDX-License-Identifier: GPL-2.0-or-later
/* sched.c - SPU scheduler.
*
* Copyright (C) IBM 2005
* Author: Mark Nutter <[email protected]>
*
* 2006-03-31 NUMA domains added.
*/
#undef DEBUG
#include <linux/errno.h>
#include <linux/sched/signal.h>
#include <linux/sched/loadavg.h>
#include <linux/sched/rt.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/completion.h>
#include <linux/vmalloc.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/numa.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
#include <linux/kthread.h>
#include <linux/pid_namespace.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/spu.h>
#include <asm/spu_csa.h>
#include <asm/spu_priv1.h>
#include "spufs.h"
#define CREATE_TRACE_POINTS
#include "sputrace.h"
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.
*/
cpumask_copy(&ctx->cpus_allowed, current->cpus_ptr);
/* Save the current cpu id for spu interrupt routing. */
ctx->last_ran = raw_smp_processor_id();
}
void spu_update_sched_info(struct spu_context *ctx)
{
int node;
if (ctx->state == SPU_STATE_RUNNABLE) {
node = ctx->spu->node;
/*
* Take list_mutex to sync with find_victim().
*/
mutex_lock(&cbe_spu_info[node].list_mutex);
__spu_update_sched_info(ctx);
mutex_unlock(&cbe_spu_info[node].list_mutex);
} else {
__spu_update_sched_info(ctx);
}
}
static int __node_allowed(struct spu_context *ctx, int node)
{
if (nr_cpus_node(node)) {
const struct cpumask *mask = cpumask_of_node(node);
if (cpumask_intersects(mask, &ctx->cpus_allowed))
return 1;
}
return 0;
}
static int node_allowed(struct spu_context *ctx, int node)
{
int rval;
spin_lock(&spu_prio->runq_lock);
rval = __node_allowed(ctx, node);
spin_unlock(&spu_prio->runq_lock);
return rval;
}
void do_notify_spus_active(void)
{
int node;
/*
* Wake up the active spu_contexts.
*/
for_each_online_node(node) {
struct spu *spu;
mutex_lock(&cbe_spu_info[node].list_mutex);
list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
if (spu->alloc_state != SPU_FREE) {
struct spu_context *ctx = spu->ctx;
set_bit(SPU_SCHED_NOTIFY_ACTIVE,
&ctx->sched_flags);
mb();
wake_up_all(&ctx->stop_wq);
}
}
mutex_unlock(&cbe_spu_info[node].list_mutex);
}
}
/**
* spu_bind_context - bind spu context to physical spu
* @spu: physical spu to bind to
* @ctx: context to bind
*/
static void spu_bind_context(struct spu *spu, struct spu_context *ctx)
{
spu_context_trace(spu_bind_context__enter, ctx, spu);
spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
if (ctx->flags & SPU_CREATE_NOSCHED)
atomic_inc(&cbe_spu_info[spu->node].reserved_spus);
ctx->stats.slb_flt_base = spu->stats.slb_flt;
ctx->stats.class2_intr_base = spu->stats.class2_intr;
spu_associate_mm(spu, ctx->owner);
spin_lock_irq(&spu->register_lock);
spu->ctx = ctx;
spu->flags = 0;
ctx->spu = spu;
ctx->ops = &spu_hw_ops;
spu->pid = current->pid;
spu->tgid = current->tgid;
spu->ibox_callback = spufs_ibox_callback;
spu->wbox_callback = spufs_wbox_callback;
spu->stop_callback = spufs_stop_callback;
spu->mfc_callback = spufs_mfc_callback;
spin_unlock_irq(&spu->register_lock);
spu_unmap_mappings(ctx);
spu_switch_log_notify(spu, ctx, SWITCH_LOG_START, 0);
spu_restore(&ctx->csa, spu);
spu->timestamp = jiffies;
ctx->state = SPU_STATE_RUNNABLE;
spuctx_switch_state(ctx, SPU_UTIL_USER);
}
/*
* Must be used with the list_mutex held.
*/
static inline int sched_spu(struct spu *spu)
{
BUG_ON(!mutex_is_locked(&cbe_spu_info[spu->node].list_mutex));
return (!spu->ctx || !(spu->ctx->flags & SPU_CREATE_NOSCHED));
}
static void aff_merge_remaining_ctxs(struct spu_gang *gang)
{
struct spu_context *ctx;
list_for_each_entry(ctx, &gang->aff_list_head, aff_list) {
if (list_empty(&ctx->aff_list))
list_add(&ctx->aff_list, &gang->aff_list_head);
}
gang->aff_flags |= AFF_MERGED;
}
static void aff_set_offsets(struct spu_gang *gang)
{
struct spu_context *ctx;
int offset;
offset = -1;
list_for_each_entry_reverse(ctx, &gang->aff_ref_ctx->aff_list,
aff_list) {
if (&ctx->aff_list == &gang->aff_list_head)
break;
ctx->aff_offset = offset--;
}
offset = 0;
list_for_each_entry(ctx, gang->aff_ref_ctx->aff_list.prev, aff_list) {
if (&ctx->aff_list == &gang->aff_list_head)
break;
ctx->aff_offset = offset++;
}
gang->aff_flags |= AFF_OFFSETS_SET;
}
static struct spu *aff_ref_location(struct spu_context *ctx, int mem_aff,
int group_size, int lowest_offset)
{
struct spu *spu;
int node, n;
/*
* TODO: A better algorithm could be used to find a good spu to be
* used as reference location for the ctxs chain.
*/
node = cpu_to_node(raw_smp_processor_id());
for (n = 0; n < MAX_NUMNODES; n++, node++) {
/*
* "available_spus" counts how many spus are not potentially
* going to be used by other affinity gangs whose reference
* context is already in place. Although this code seeks to
* avoid having affinity gangs with a summed amount of
* contexts bigger than the amount of spus in the node,
* this may happen sporadically. In this case, available_spus
* becomes negative, which is harmless.
*/
int available_spus;
node = (node < MAX_NUMNODES) ? node : 0;
if (!node_allowed(ctx, node))
continue;
available_spus = 0;
mutex_lock(&cbe_spu_info[node].list_mutex);
list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
if (spu->ctx && spu->ctx->gang && !spu->ctx->aff_offset
&& spu->ctx->gang->aff_ref_spu)
available_spus -= spu->ctx->gang->contexts;
available_spus++;
}
if (available_spus < ctx->gang->contexts) {
mutex_unlock(&cbe_spu_info[node].list_mutex);
continue;
}
list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
if ((!mem_aff || spu->has_mem_affinity) &&
sched_spu(spu)) {
mutex_unlock(&cbe_spu_info[node].list_mutex);
return spu;
}
}
mutex_unlock(&cbe_spu_info[node].list_mutex);
}
return NULL;
}
static void aff_set_ref_point_location(struct spu_gang *gang)
{
int mem_aff, gs, lowest_offset;
struct spu_context *tmp, *ctx;
mem_aff = gang->aff_ref_ctx->flags & SPU_CREATE_AFFINITY_MEM;
lowest_offset = 0;
gs = 0;
list_for_each_entry(tmp, &gang->aff_list_head, aff_list)
gs++;
list_for_each_entry_reverse(ctx, &gang->aff_ref_ctx->aff_list,
aff_list) {
if (&ctx->aff_list == &gang->aff_list_head)
break;
lowest_offset = ctx->aff_offset;
}
gang->aff_ref_spu = aff_ref_location(gang->aff_ref_ctx, mem_aff, gs,
lowest_offset);
}
static struct spu *ctx_location(struct spu *ref, int offset, int node)
{
struct spu *spu;
spu = NULL;
if (offset >= 0) {
list_for_each_entry(spu, ref->aff_list.prev, aff_list) {
BUG_ON(spu->node != node);
if (offset == 0)
break;
if (sched_spu(spu))
offset--;
}
} else {
list_for_each_entry_reverse(spu, ref->aff_list.next, aff_list) {
BUG_ON(spu->node != node);
if (offset == 0)
break;
if (sched_spu(spu))
offset++;
}
}
return spu;
}
/*
* affinity_check is called each time a context is going to be scheduled.
* It returns the spu ptr on which the context must run.
*/
static int has_affinity(struct spu_context *ctx)
{
struct spu_gang *gang = ctx->gang;
if (list_empty(&ctx->aff_list))
return 0;
if (atomic_read(&ctx->gang->aff_sched_count) == 0)
ctx->gang->aff_ref_spu = NULL;
if (!gang->aff_ref_spu) {
if (!(gang->aff_flags & AFF_MERGED))
aff_merge_remaining_ctxs(gang);
if (!(gang->aff_flags & AFF_OFFSETS_SET))
aff_set_offsets(gang);
aff_set_ref_point_location(gang);
}
return gang->aff_ref_spu != NULL;
}
/**
* spu_unbind_context - unbind spu context from physical spu
* @spu: physical spu to unbind from
* @ctx: context to unbind
*/
static void spu_unbind_context(struct spu *spu, struct spu_context *ctx)
{
u32 status;
spu_context_trace(spu_unbind_context__enter, ctx, spu);
spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
if (spu->ctx->flags & SPU_CREATE_NOSCHED)
atomic_dec(&cbe_spu_info[spu->node].reserved_spus);
if (ctx->gang)
/*
* If ctx->gang->aff_sched_count is positive, SPU affinity is
* being considered in this gang. Using atomic_dec_if_positive
* allow us to skip an explicit check for affinity in this gang
*/
atomic_dec_if_positive(&ctx->gang->aff_sched_count);
spu_unmap_mappings(ctx);
spu_save(&ctx->csa, spu);
spu_switch_log_notify(spu, ctx, SWITCH_LOG_STOP, 0);
spin_lock_irq(&spu->register_lock);
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->pid = 0;
spu->tgid = 0;
ctx->ops = &spu_backing_ops;
spu->flags = 0;
spu->ctx = NULL;
spin_unlock_irq(&spu->register_lock);
spu_associate_mm(spu, NULL);
ctx->stats.slb_flt +=
(spu->stats.slb_flt - ctx->stats.slb_flt_base);
ctx->stats.class2_intr +=
(spu->stats.class2_intr - ctx->stats.class2_intr_base);
/* This maps the underlying spu state to idle */
spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
ctx->spu = NULL;
if (spu_stopped(ctx, &status))
wake_up_all(&ctx->stop_wq);
}
/**
* spu_add_to_rq - add a context to the runqueue
* @ctx: context to add
*/
static void __spu_add_to_rq(struct spu_context *ctx)
{
/*
* Unfortunately this code path can be called from multiple threads
* on behalf of a single context due to the way the problem state
* mmap support works.
*
* Fortunately we need to wake up all these threads at the same time
* and can simply skip the runqueue addition for every but the first
* thread getting into this codepath.
*
* It's still quite hacky, and long-term we should proxy all other
* threads through the owner thread so that spu_run is in control
* of all the scheduling activity for a given context.
*/
if (list_empty(&ctx->rq)) {
list_add_tail(&ctx->rq, &spu_prio->runq[ctx->prio]);
set_bit(ctx->prio, spu_prio->bitmap);
if (!spu_prio->nr_waiting++)
mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK);
}
}
static void spu_add_to_rq(struct spu_context *ctx)
{
spin_lock(&spu_prio->runq_lock);
__spu_add_to_rq(ctx);
spin_unlock(&spu_prio->runq_lock);
}
static void __spu_del_from_rq(struct spu_context *ctx)
{
int prio = ctx->prio;
if (!list_empty(&ctx->rq)) {
if (!--spu_prio->nr_waiting)
del_timer(&spusched_timer);
list_del_init(&ctx->rq);
if (list_empty(&spu_prio->runq[prio]))
clear_bit(prio, spu_prio->bitmap);
}
}
void spu_del_from_rq(struct spu_context *ctx)
{
spin_lock(&spu_prio->runq_lock);
__spu_del_from_rq(ctx);
spin_unlock(&spu_prio->runq_lock);
}
static void spu_prio_wait(struct spu_context *ctx)
{
DEFINE_WAIT(wait);
/*
* The caller must explicitly wait for a context to be loaded
* if the nosched flag is set. If NOSCHED is not set, the caller
* queues the context and waits for an spu event or error.
*/
BUG_ON(!(ctx->flags & SPU_CREATE_NOSCHED));
spin_lock(&spu_prio->runq_lock);
prepare_to_wait_exclusive(&ctx->stop_wq, &wait, TASK_INTERRUPTIBLE);
if (!signal_pending(current)) {
__spu_add_to_rq(ctx);
spin_unlock(&spu_prio->runq_lock);
mutex_unlock(&ctx->state_mutex);
schedule();
mutex_lock(&ctx->state_mutex);
spin_lock(&spu_prio->runq_lock);
__spu_del_from_rq(ctx);
}
spin_unlock(&spu_prio->runq_lock);
__set_current_state(TASK_RUNNING);
remove_wait_queue(&ctx->stop_wq, &wait);
}
static struct spu *spu_get_idle(struct spu_context *ctx)
{
struct spu *spu, *aff_ref_spu;
int node, n;
spu_context_nospu_trace(spu_get_idle__enter, ctx);
if (ctx->gang) {
mutex_lock(&ctx->gang->aff_mutex);
if (has_affinity(ctx)) {
aff_ref_spu = ctx->gang->aff_ref_spu;
atomic_inc(&ctx->gang->aff_sched_count);
mutex_unlock(&ctx->gang->aff_mutex);
node = aff_ref_spu->node;
mutex_lock(&cbe_spu_info[node].list_mutex);
spu = ctx_location(aff_ref_spu, ctx->aff_offset, node);
if (spu && spu->alloc_state == SPU_FREE)
goto found;
mutex_unlock(&cbe_spu_info[node].list_mutex);
atomic_dec(&ctx->gang->aff_sched_count);
goto not_found;
}
mutex_unlock(&ctx->gang->aff_mutex);
}
node = cpu_to_node(raw_smp_processor_id());
for (n = 0; n < MAX_NUMNODES; n++, node++) {
node = (node < MAX_NUMNODES) ? node : 0;
if (!node_allowed(ctx, node))
continue;
mutex_lock(&cbe_spu_info[node].list_mutex);
list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
if (spu->alloc_state == SPU_FREE)
goto found;
}
mutex_unlock(&cbe_spu_info[node].list_mutex);
}
not_found:
spu_context_nospu_trace(spu_get_idle__not_found, ctx);
return NULL;
found:
spu->alloc_state = SPU_USED;
mutex_unlock(&cbe_spu_info[node].list_mutex);
spu_context_trace(spu_get_idle__found, ctx, spu);
spu_init_channels(spu);
return spu;
}
/**
* find_victim - find a lower priority context to preempt
* @ctx: candidate context for running
*
* Returns the freed physical spu to run the new context on.
*/
static struct spu *find_victim(struct spu_context *ctx)
{
struct spu_context *victim = NULL;
struct spu *spu;
int node, n;
spu_context_nospu_trace(spu_find_victim__enter, ctx);
/*
* Look for a possible preemption candidate on the local node first.
* If there is no candidate look at the other nodes. This isn't
* exactly fair, but so far the whole spu scheduler tries to keep
* a strong node affinity. We might want to fine-tune this in
* the future.
*/
restart:
node = cpu_to_node(raw_smp_processor_id());
for (n = 0; n < MAX_NUMNODES; n++, node++) {
node = (node < MAX_NUMNODES) ? node : 0;
if (!node_allowed(ctx, node))
continue;
mutex_lock(&cbe_spu_info[node].list_mutex);
list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
struct spu_context *tmp = spu->ctx;
if (tmp && tmp->prio > ctx->prio &&
!(tmp->flags & SPU_CREATE_NOSCHED) &&
(!victim || tmp->prio > victim->prio)) {
victim = spu->ctx;
}
}
if (victim)
get_spu_context(victim);
mutex_unlock(&cbe_spu_info[node].list_mutex);
if (victim) {
/*
* This nests ctx->state_mutex, but we always lock
* higher priority contexts before lower priority
* ones, so this is safe until we introduce
* priority inheritance schemes.
*
* XXX if the highest priority context is locked,
* this can loop a long time. Might be better to
* look at another context or give up after X retries.
*/
if (!mutex_trylock(&victim->state_mutex)) {
put_spu_context(victim);
victim = NULL;
goto restart;
}
spu = victim->spu;
if (!spu || victim->prio <= ctx->prio) {
/*
* This race can happen because we've dropped
* the active list mutex. Not a problem, just
* restart the search.
*/
mutex_unlock(&victim->state_mutex);
put_spu_context(victim);
victim = NULL;
goto restart;
}
spu_context_trace(__spu_deactivate__unload, ctx, spu);
mutex_lock(&cbe_spu_info[node].list_mutex);
cbe_spu_info[node].nr_active--;
spu_unbind_context(spu, victim);
mutex_unlock(&cbe_spu_info[node].list_mutex);
victim->stats.invol_ctx_switch++;
spu->stats.invol_ctx_switch++;
if (test_bit(SPU_SCHED_SPU_RUN, &victim->sched_flags))
spu_add_to_rq(victim);
mutex_unlock(&victim->state_mutex);
put_spu_context(victim);
return spu;
}
}
return NULL;
}
static void __spu_schedule(struct spu *spu, struct spu_context *ctx)
{
int node = spu->node;
int success = 0;
spu_set_timeslice(ctx);
mutex_lock(&cbe_spu_info[node].list_mutex);
if (spu->ctx == NULL) {
spu_bind_context(spu, ctx);
cbe_spu_info[node].nr_active++;
spu->alloc_state = SPU_USED;
success = 1;
}
mutex_unlock(&cbe_spu_info[node].list_mutex);
if (success)
wake_up_all(&ctx->run_wq);
else
spu_add_to_rq(ctx);
}
static void spu_schedule(struct spu *spu, struct spu_context *ctx)
{
/* not a candidate for interruptible because it's called either
from the scheduler thread or from spu_deactivate */
mutex_lock(&ctx->state_mutex);
if (ctx->state == SPU_STATE_SAVED)
__spu_schedule(spu, ctx);
spu_release(ctx);
}
/**
* spu_unschedule - remove a context from a spu, and possibly release it.
* @spu: The SPU to unschedule from
* @ctx: The context currently scheduled on the SPU
* @free_spu Whether to free the SPU for other contexts
*
* Unbinds the context @ctx from the SPU @spu. If @free_spu is non-zero, the
* SPU is made available for other contexts (ie, may be returned by
* spu_get_idle). If this is zero, the caller is expected to schedule another
* context to this spu.
*
* Should be called with ctx->state_mutex held.
*/
static void spu_unschedule(struct spu *spu, struct spu_context *ctx,
int free_spu)
{
int node = spu->node;
mutex_lock(&cbe_spu_info[node].list_mutex);
cbe_spu_info[node].nr_active--;
if (free_spu)
spu->alloc_state = SPU_FREE;
spu_unbind_context(spu, ctx);
ctx->stats.invol_ctx_switch++;
spu->stats.invol_ctx_switch++;
mutex_unlock(&cbe_spu_info[node].list_mutex);
}
/**
* spu_activate - find a free spu for a context and execute it
* @ctx: spu context to schedule
* @flags: flags (currently ignored)
*
* Tries to find a free spu to run @ctx. If no free spu is available
* add the context to the runqueue so it gets woken up once an spu
* is available.
*/
int spu_activate(struct spu_context *ctx, unsigned long flags)
{
struct spu *spu;
/*
* If there are multiple threads waiting for a single context
* only one actually binds the context while the others will
* only be able to acquire the state_mutex once the context
* already is in runnable state.
*/
if (ctx->spu)
return 0;
spu_activate_top:
if (signal_pending(current))
return -ERESTARTSYS;
spu = spu_get_idle(ctx);
/*
* If this is a realtime thread we try to get it running by
* preempting a lower priority thread.
*/
if (!spu && rt_prio(ctx->prio))
spu = find_victim(ctx);
if (spu) {
unsigned long runcntl;
runcntl = ctx->ops->runcntl_read(ctx);
__spu_schedule(spu, ctx);
if (runcntl & SPU_RUNCNTL_RUNNABLE)
spuctx_switch_state(ctx, SPU_UTIL_USER);
return 0;
}
if (ctx->flags & SPU_CREATE_NOSCHED) {
spu_prio_wait(ctx);
goto spu_activate_top;
}
spu_add_to_rq(ctx);
return 0;
}
/**
* grab_runnable_context - try to find a runnable context
*
* Remove the highest priority context on the runqueue and return it
* to the caller. Returns %NULL if no runnable context was found.
*/
static struct spu_context *grab_runnable_context(int prio, int node)
{
struct spu_context *ctx;
int best;
spin_lock(&spu_prio->runq_lock);
best = find_first_bit(spu_prio->bitmap, prio);
while (best < prio) {
struct list_head *rq = &spu_prio->runq[best];
list_for_each_entry(ctx, rq, rq) {
/* XXX(hch): check for affinity here as well */
if (__node_allowed(ctx, node)) {
__spu_del_from_rq(ctx);
goto found;
}
}
best++;
}
ctx = NULL;
found:
spin_unlock(&spu_prio->runq_lock);
return ctx;
}
static int __spu_deactivate(struct spu_context *ctx, int force, int max_prio)
{
struct spu *spu = ctx->spu;
struct spu_context *new = NULL;
if (spu) {
new = grab_runnable_context(max_prio, spu->node);
if (new || force) {
spu_unschedule(spu, ctx, new == NULL);
if (new) {
if (new->flags & SPU_CREATE_NOSCHED)
wake_up(&new->stop_wq);
else {
spu_release(ctx);
spu_schedule(spu, new);
/* this one can't easily be made
interruptible */
mutex_lock(&ctx->state_mutex);
}
}
}
}
return new != NULL;
}
/**
* spu_deactivate - unbind a context from its physical spu
* @ctx: spu context to unbind
*
* Unbind @ctx from the physical spu it is running on and schedule
* the highest priority context to run on the freed physical spu.
*/
void spu_deactivate(struct spu_context *ctx)
{
spu_context_nospu_trace(spu_deactivate__enter, ctx);
__spu_deactivate(ctx, 1, MAX_PRIO);
}
/**
* spu_yield - yield a physical spu if others are waiting
* @ctx: spu context to yield
*
* Check if there is a higher priority context waiting and if yes
* unbind @ctx from the physical spu and schedule the highest
* priority context to run on the freed physical spu instead.
*/
void spu_yield(struct spu_context *ctx)
{
spu_context_nospu_trace(spu_yield__enter, ctx);
if (!(ctx->flags & SPU_CREATE_NOSCHED)) {
mutex_lock(&ctx->state_mutex);
__spu_deactivate(ctx, 0, MAX_PRIO);
mutex_unlock(&ctx->state_mutex);
}
}
static noinline void spusched_tick(struct spu_context *ctx)
{
struct spu_context *new = NULL;
struct spu *spu = NULL;
if (spu_acquire(ctx))
BUG(); /* a kernel thread never has signals pending */
if (ctx->state != SPU_STATE_RUNNABLE)
goto out;
if (ctx->flags & SPU_CREATE_NOSCHED)
goto out;
if (ctx->policy == SCHED_FIFO)
goto out;
if (--ctx->time_slice && test_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags))
goto out;
spu = ctx->spu;
spu_context_trace(spusched_tick__preempt, ctx, spu);
new = grab_runnable_context(ctx->prio + 1, spu->node);
if (new) {
spu_unschedule(spu, ctx, 0);
if (test_bit(SPU_SCHED_SPU_RUN, &ctx->sched_flags))
spu_add_to_rq(ctx);
} else {
spu_context_nospu_trace(spusched_tick__newslice, ctx);
if (!ctx->time_slice)
ctx->time_slice++;
}
out:
spu_release(ctx);
if (new)
spu_schedule(spu, new);
}
/**
* count_active_contexts - count nr of active tasks
*
* Return the number of tasks currently running or waiting to run.
*
* Note that we don't take runq_lock / list_mutex here. Reading
* a single 32bit value is atomic on powerpc, and we don't care
* about memory ordering issues here.
*/
static unsigned long count_active_contexts(void)
{
int nr_active = 0, node;
for (node = 0; node < MAX_NUMNODES; node++)
nr_active += cbe_spu_info[node].nr_active;
nr_active += spu_prio->nr_waiting;
return nr_active;
}
/**
* spu_calc_load - update the avenrun load estimates.
*
* No locking against reading these values from userspace, as for
* the CPU loadavg code.
*/
static void spu_calc_load(void)
{
unsigned long active_tasks; /* fixed-point */
active_tasks = count_active_contexts() * FIXED_1;
spu_avenrun[0] = calc_load(spu_avenrun[0], EXP_1, active_tasks);
spu_avenrun[1] = calc_load(spu_avenrun[1], EXP_5, active_tasks);
spu_avenrun[2] = calc_load(spu_avenrun[2], EXP_15, active_tasks);
}
static void spusched_wake(struct timer_list *unused)
{
mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK);
wake_up_process(spusched_task);
}
static void spuloadavg_wake(struct timer_list *unused)
{
mod_timer(&spuloadavg_timer, jiffies + LOAD_FREQ);
spu_calc_load();
}
static int spusched_thread(void *unused)
{
struct spu *spu;
int node;
while (!kthread_should_stop()) {
set_current_state(TASK_INTERRUPTIBLE);
schedule();
for (node = 0; node < MAX_NUMNODES; node++) {
struct mutex *mtx = &cbe_spu_info[node].list_mutex;
mutex_lock(mtx);
list_for_each_entry(spu, &cbe_spu_info[node].spus,
cbe_list) {
struct spu_context *ctx = spu->ctx;
if (ctx) {
get_spu_context(ctx);
mutex_unlock(mtx);
spusched_tick(ctx);
mutex_lock(mtx);
put_spu_context(ctx);
}
}
mutex_unlock(mtx);
}
}
return 0;
}
void spuctx_switch_state(struct spu_context *ctx,
enum spu_utilization_state new_state)
{
unsigned long long curtime;
signed long long delta;
struct spu *spu;
enum spu_utilization_state old_state;
int node;
curtime = ktime_get_ns();
delta = curtime - ctx->stats.tstamp;
WARN_ON(!mutex_is_locked(&ctx->state_mutex));
WARN_ON(delta < 0);
spu = ctx->spu;
old_state = ctx->stats.util_state;
ctx->stats.util_state = new_state;
ctx->stats.tstamp = curtime;
/*
* Update the physical SPU utilization statistics.
*/
if (spu) {
ctx->stats.times[old_state] += delta;
spu->stats.times[old_state] += delta;
spu->stats.util_state = new_state;
spu->stats.tstamp = curtime;
node = spu->node;
if (old_state == SPU_UTIL_USER)
atomic_dec(&cbe_spu_info[node].busy_spus);
if (new_state == SPU_UTIL_USER)
atomic_inc(&cbe_spu_info[node].busy_spus);
}
}
#ifdef CONFIG_PROC_FS
static int show_spu_loadavg(struct seq_file *s, void *private)
{
int a, b, c;
a = spu_avenrun[0] + (FIXED_1/200);
b = spu_avenrun[1] + (FIXED_1/200);
c = spu_avenrun[2] + (FIXED_1/200);
/*
* Note that last_pid doesn't really make much sense for the
* SPU loadavg (it even seems very odd on the CPU side...),
* but we include it here to have a 100% compatible interface.
*/
seq_printf(s, "%d.%02d %d.%02d %d.%02d %ld/%d %d\n",
LOAD_INT(a), LOAD_FRAC(a),
LOAD_INT(b), LOAD_FRAC(b),
LOAD_INT(c), LOAD_FRAC(c),
count_active_contexts(),
atomic_read(&nr_spu_contexts),
idr_get_cursor(&task_active_pid_ns(current)->idr) - 1);
return 0;
}
#endif
int __init spu_sched_init(void)
{
struct proc_dir_entry *entry;
int err = -ENOMEM, i;
spu_prio = kzalloc(sizeof(struct spu_prio_array), GFP_KERNEL);
if (!spu_prio)
goto out;
for (i = 0; i < MAX_PRIO; i++) {
INIT_LIST_HEAD(&spu_prio->runq[i]);
__clear_bit(i, spu_prio->bitmap);
}
spin_lock_init(&spu_prio->runq_lock);
timer_setup(&spusched_timer, spusched_wake, 0);
timer_setup(&spuloadavg_timer, spuloadavg_wake, 0);
spusched_task = kthread_run(spusched_thread, NULL, "spusched");
if (IS_ERR(spusched_task)) {
err = PTR_ERR(spusched_task);
goto out_free_spu_prio;
}
mod_timer(&spuloadavg_timer, 0);
entry = proc_create_single("spu_loadavg", 0, NULL, show_spu_loadavg);
if (!entry)
goto out_stop_kthread;
pr_debug("spusched: tick: %d, min ticks: %d, default ticks: %d\n",
SPUSCHED_TICK, MIN_SPU_TIMESLICE, DEF_SPU_TIMESLICE);
return 0;
out_stop_kthread:
kthread_stop(spusched_task);
out_free_spu_prio:
kfree(spu_prio);
out:
return err;
}
void spu_sched_exit(void)
{
struct spu *spu;
int node;
remove_proc_entry("spu_loadavg", NULL);
del_timer_sync(&spusched_timer);
del_timer_sync(&spuloadavg_timer);
kthread_stop(spusched_task);
for (node = 0; node < MAX_NUMNODES; node++) {
mutex_lock(&cbe_spu_info[node].list_mutex);
list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list)
if (spu->alloc_state != SPU_FREE)
spu->alloc_state = SPU_FREE;
mutex_unlock(&cbe_spu_info[node].list_mutex);
}
kfree(spu_prio);
}
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