diff options
Diffstat (limited to 'arch/powerpc/platforms/cell/spufs/sched.c')
| -rw-r--r-- | arch/powerpc/platforms/cell/spufs/sched.c | 1145 |
1 files changed, 1145 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c new file mode 100644 index 000000000..f18d5067c --- /dev/null +++ b/arch/powerpc/platforms/cell/spufs/sched.c @@ -0,0 +1,1145 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* sched.c - SPU scheduler. + * + * Copyright (C) IBM 2005 + * Author: Mark Nutter <mnutter@us.ibm.com> + * + * 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) / (MAX_USER_PRIO / 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. + * + * When the awakened processes see their "notify_active" flag is set, + * they will call spu_switch_notify(). + */ + 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; + spu_switch_notify(spu, ctx); + 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 *ctx; + struct spu *tmp; + + 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_switch_notify(spu, NULL); + 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 it's 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); + } +} + +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; +}; + +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); +} |