linux/arch/powerpc/platforms/cell/spufs/sched.c
Andre Detsch 27ec41d3a1 [CELL] spufs: add spu stats in sysfs and ctx stat file in spufs
This patch exports per-context statistics in spufs as long as spu
statistics in sysfs.

It was formed by merging:
"spufs: add spu stats in sysfs"   From: Christoph Hellwig
"spufs: add stat file to spufs"   From: Christoph Hellwig
"spufs: fix libassist accounting" From: Jeremy Kerr
"spusched: fix spu utilization statistics" From: Luke Browning
And some adjustments by myself, after suggestions on cbe-oss-dev.

Having separate patches was making the review process harder
than it should, as we end up integrating spus and ctx statistics
accounting much more than it was on the first implementation.

Signed-off-by: Andre Detsch <adetsch@br.ibm.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
2007-07-20 21:41:50 +02:00

793 lines
20 KiB
C

/* sched.c - SPU scheduler.
*
* Copyright (C) IBM 2005
* Author: Mark Nutter <mnutter@us.ibm.com>
*
* 2006-03-31 NUMA domains added.
*
* 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/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/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"
struct spu_prio_array {
DECLARE_BITMAP(bitmap, MAX_PRIO);
struct list_head runq[MAX_PRIO];
spinlock_t runq_lock;
struct list_head active_list[MAX_NUMNODES];
struct mutex active_mutex[MAX_NUMNODES];
int nr_active[MAX_NUMNODES];
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;
/*
* 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 MAX_USER_PRIO (MAX_PRIO - MAX_RT_PRIO)
#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)
{
/*
* 32-Bit assignment are atomic on powerpc, and we don't care about
* memory ordering here because retriving the controlling thread is
* per defintion racy.
*/
ctx->tid = current->pid;
/*
* We do our own priority calculations, so we normally want
* ->static_prio to start with. Unfortunately thies 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;
/*
* A lot of places that don't hold active_mutex poke into
* cpus_allowed, including grab_runnable_context which
* already holds the runq_lock. So abuse runq_lock
* to protect this field aswell.
*/
spin_lock(&spu_prio->runq_lock);
ctx->cpus_allowed = current->cpus_allowed;
spin_unlock(&spu_prio->runq_lock);
}
void spu_update_sched_info(struct spu_context *ctx)
{
int node = ctx->spu->node;
mutex_lock(&spu_prio->active_mutex[node]);
__spu_update_sched_info(ctx);
mutex_unlock(&spu_prio->active_mutex[node]);
}
static int __node_allowed(struct spu_context *ctx, int node)
{
if (nr_cpus_node(node)) {
cpumask_t mask = node_to_cpumask(node);
if (cpus_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;
}
/**
* spu_add_to_active_list - add spu to active list
* @spu: spu to add to the active list
*/
static void spu_add_to_active_list(struct spu *spu)
{
int node = spu->node;
mutex_lock(&spu_prio->active_mutex[node]);
spu_prio->nr_active[node]++;
list_add_tail(&spu->list, &spu_prio->active_list[node]);
mutex_unlock(&spu_prio->active_mutex[node]);
}
static void __spu_remove_from_active_list(struct spu *spu)
{
list_del_init(&spu->list);
spu_prio->nr_active[spu->node]--;
}
/**
* spu_remove_from_active_list - remove spu from active list
* @spu: spu to remove from the active list
*/
static void spu_remove_from_active_list(struct spu *spu)
{
int node = spu->node;
mutex_lock(&spu_prio->active_mutex[node]);
__spu_remove_from_active_list(spu);
mutex_unlock(&spu_prio->active_mutex[node]);
}
static BLOCKING_NOTIFIER_HEAD(spu_switch_notifier);
static void spu_switch_notify(struct spu *spu, struct spu_context *ctx)
{
blocking_notifier_call_chain(&spu_switch_notifier,
ctx ? ctx->object_id : 0, spu);
}
int spu_switch_event_register(struct notifier_block * n)
{
return blocking_notifier_chain_register(&spu_switch_notifier, n);
}
int spu_switch_event_unregister(struct notifier_block * n)
{
return blocking_notifier_chain_unregister(&spu_switch_notifier, n);
}
/**
* 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)
{
pr_debug("%s: pid=%d SPU=%d NODE=%d\n", __FUNCTION__, current->pid,
spu->number, spu->node);
spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
ctx->stats.slb_flt_base = spu->stats.slb_flt;
ctx->stats.class2_intr_base = spu->stats.class2_intr;
spu->ctx = ctx;
spu->flags = 0;
ctx->spu = spu;
ctx->ops = &spu_hw_ops;
spu->pid = current->pid;
spu_associate_mm(spu, ctx->owner);
spu->ibox_callback = spufs_ibox_callback;
spu->wbox_callback = spufs_wbox_callback;
spu->stop_callback = spufs_stop_callback;
spu->mfc_callback = spufs_mfc_callback;
spu->dma_callback = spufs_dma_callback;
mb();
spu_unmap_mappings(ctx);
spu_restore(&ctx->csa, spu);
spu->timestamp = jiffies;
spu_cpu_affinity_set(spu, raw_smp_processor_id());
spu_switch_notify(spu, ctx);
ctx->state = SPU_STATE_RUNNABLE;
spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
}
/**
* 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)
{
pr_debug("%s: unbind pid=%d SPU=%d NODE=%d\n", __FUNCTION__,
spu->pid, spu->number, spu->node);
spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
spu_switch_notify(spu, NULL);
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->dma_callback = NULL;
spu_associate_mm(spu, NULL);
spu->pid = 0;
ctx->ops = &spu_backing_ops;
spu->flags = 0;
spu->ctx = 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;
}
/**
* 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_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);
}
}
static void spu_prio_wait(struct spu_context *ctx)
{
DEFINE_WAIT(wait);
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 = NULL;
int node = cpu_to_node(raw_smp_processor_id());
int n;
for (n = 0; n < MAX_NUMNODES; n++, node++) {
node = (node < MAX_NUMNODES) ? node : 0;
if (!node_allowed(ctx, node))
continue;
spu = spu_alloc_node(node);
if (spu)
break;
}
return spu;
}
/**
* find_victim - find a lower priority context to preempt
* @ctx: canidate 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;
/*
* 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 schedule 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(&spu_prio->active_mutex[node]);
list_for_each_entry(spu, &spu_prio->active_list[node], list) {
struct spu_context *tmp = spu->ctx;
if (tmp->prio > ctx->prio &&
(!victim || tmp->prio > victim->prio))
victim = spu->ctx;
}
mutex_unlock(&spu_prio->active_mutex[node]);
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.
*/
if (!mutex_trylock(&victim->state_mutex)) {
victim = NULL;
goto restart;
}
spu = victim->spu;
if (!spu) {
/*
* This race can happen because we've dropped
* the active list mutex. No a problem, just
* restart the search.
*/
mutex_unlock(&victim->state_mutex);
victim = NULL;
goto restart;
}
spu_remove_from_active_list(spu);
spu_unbind_context(spu, victim);
victim->stats.invol_ctx_switch++;
spu->stats.invol_ctx_switch++;
mutex_unlock(&victim->state_mutex);
/*
* We need to break out of the wait loop in spu_run
* manually to ensure this context gets put on the
* runqueue again ASAP.
*/
wake_up(&victim->stop_wq);
return spu;
}
}
return NULL;
}
/**
* 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)
{
do {
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 = 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) {
spu_bind_context(spu, ctx);
spu_add_to_active_list(spu);
return 0;
}
spu_prio_wait(ctx);
} while (!signal_pending(current));
return -ERESTARTSYS;
}
/**
* 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 = sched_find_first_bit(spu_prio->bitmap);
while (best < prio) {
struct list_head *rq = &spu_prio->runq[best];
list_for_each_entry(ctx, rq, rq) {
/* XXX(hch): check for affinity here aswell */
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_remove_from_active_list(spu);
spu_unbind_context(spu, ctx);
ctx->stats.vol_ctx_switch++;
spu->stats.vol_ctx_switch++;
spu_free(spu);
if (new)
wake_up(&new->stop_wq);
}
}
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_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)
{
if (!(ctx->flags & SPU_CREATE_NOSCHED)) {
mutex_lock(&ctx->state_mutex);
__spu_deactivate(ctx, 0, MAX_PRIO);
mutex_unlock(&ctx->state_mutex);
}
}
static void spusched_tick(struct spu_context *ctx)
{
if (ctx->flags & SPU_CREATE_NOSCHED)
return;
if (ctx->policy == SCHED_FIFO)
return;
if (--ctx->time_slice)
return;
/*
* Unfortunately active_mutex ranks outside of state_mutex, so
* we have to trylock here. If we fail give the context another
* tick and try again.
*/
if (mutex_trylock(&ctx->state_mutex)) {
struct spu *spu = ctx->spu;
struct spu_context *new;
new = grab_runnable_context(ctx->prio + 1, spu->node);
if (new) {
__spu_remove_from_active_list(spu);
spu_unbind_context(spu, ctx);
ctx->stats.invol_ctx_switch++;
spu->stats.invol_ctx_switch++;
spu_free(spu);
wake_up(&new->stop_wq);
/*
* We need to break out of the wait loop in
* spu_run manually to ensure this context
* gets put on the runqueue again ASAP.
*/
wake_up(&ctx->stop_wq);
}
spu_set_timeslice(ctx);
mutex_unlock(&ctx->state_mutex);
} else {
ctx->time_slice++;
}
}
/**
* 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 / active_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 += spu_prio->nr_active[node];
nr_active += spu_prio->nr_waiting;
return nr_active;
}
/**
* spu_calc_load - given tick count, update the avenrun load estimates.
* @tick: tick count
*
* No locking against reading these values from userspace, as for
* the CPU loadavg code.
*/
static void spu_calc_load(unsigned long ticks)
{
unsigned long active_tasks; /* fixed-point */
static int count = LOAD_FREQ;
count -= ticks;
if (unlikely(count < 0)) {
active_tasks = count_active_contexts() * FIXED_1;
do {
CALC_LOAD(spu_avenrun[0], EXP_1, active_tasks);
CALC_LOAD(spu_avenrun[1], EXP_5, active_tasks);
CALC_LOAD(spu_avenrun[2], EXP_15, active_tasks);
count += LOAD_FREQ;
} while (count < 0);
}
}
static void spusched_wake(unsigned long data)
{
mod_timer(&spusched_timer, jiffies + SPUSCHED_TICK);
wake_up_process(spusched_task);
spu_calc_load(SPUSCHED_TICK);
}
static int spusched_thread(void *unused)
{
struct spu *spu, *next;
int node;
while (!kthread_should_stop()) {
set_current_state(TASK_INTERRUPTIBLE);
schedule();
for (node = 0; node < MAX_NUMNODES; node++) {
mutex_lock(&spu_prio->active_mutex[node]);
list_for_each_entry_safe(spu, next,
&spu_prio->active_list[node],
list)
spusched_tick(spu->ctx);
mutex_unlock(&spu_prio->active_mutex[node]);
}
}
return 0;
}
#define LOAD_INT(x) ((x) >> FSHIFT)
#define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100)
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),
current->nsproxy->pid_ns->last_pid);
return 0;
}
static int spu_loadavg_open(struct inode *inode, struct file *file)
{
return single_open(file, show_spu_loadavg, NULL);
}
static const struct file_operations spu_loadavg_fops = {
.open = spu_loadavg_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
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);
}
__set_bit(MAX_PRIO, spu_prio->bitmap);
for (i = 0; i < MAX_NUMNODES; i++) {
mutex_init(&spu_prio->active_mutex[i]);
INIT_LIST_HEAD(&spu_prio->active_list[i]);
}
spin_lock_init(&spu_prio->runq_lock);
setup_timer(&spusched_timer, spusched_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;
}
entry = create_proc_entry("spu_loadavg", 0, NULL);
if (!entry)
goto out_stop_kthread;
entry->proc_fops = &spu_loadavg_fops;
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, *tmp;
int node;
remove_proc_entry("spu_loadavg", NULL);
del_timer_sync(&spusched_timer);
kthread_stop(spusched_task);
for (node = 0; node < MAX_NUMNODES; node++) {
mutex_lock(&spu_prio->active_mutex[node]);
list_for_each_entry_safe(spu, tmp, &spu_prio->active_list[node],
list) {
list_del_init(&spu->list);
spu_free(spu);
}
mutex_unlock(&spu_prio->active_mutex[node]);
}
kfree(spu_prio);
}