[Cbe-oss-dev] [PATCH 19/21] spufs: decouple spu scheduler from spufs_spu_run (asynchronous scheduling)
Jeremy Kerr
jk at ozlabs.org
Wed Dec 5 13:49:31 EST 2007
From: Luke Browning <lukebr at linux.vnet.ibm.com>
Change spufs_spu_run so that the context is queued directly to the
scheduler and the controlling thread advances directly to spufs_wait()
for spe errors and exceptions.
nosched contexts are treated the same as before.
Fixes from Christoph Hellwig <hch at lst.de>
Signed-off-by: Luke Browning <lukebr at linux.vnet.ibm.com>
Signed-off-by: Jeremy Kerr <jk at ozlabs.org>
---
arch/powerpc/platforms/cell/spufs/context.c | 31 ---
arch/powerpc/platforms/cell/spufs/file.c | 9 +
arch/powerpc/platforms/cell/spufs/run.c | 90 ++++------
arch/powerpc/platforms/cell/spufs/sched.c | 235 ++++++++++++++++++----------
arch/powerpc/platforms/cell/spufs/spufs.h | 3
5 files changed, 200 insertions(+), 168 deletions(-)
diff --git a/arch/powerpc/platforms/cell/spufs/context.c b/arch/powerpc/platforms/cell/spufs/context.c
index 6fa24d3..290b10e 100644
--- a/arch/powerpc/platforms/cell/spufs/context.c
+++ b/arch/powerpc/platforms/cell/spufs/context.c
@@ -134,37 +134,6 @@ void spu_unmap_mappings(struct spu_context *ctx)
}
/**
- * spu_acquire_runnable - lock spu contex and make sure it is in runnable state
- * @ctx: spu contex to lock
- *
- * Note:
- * Returns 0 and with the context locked on success
- * Returns negative error and with the context _unlocked_ on failure.
- */
-int spu_acquire_runnable(struct spu_context *ctx, unsigned long flags)
-{
- int ret = -EINVAL;
-
- spu_acquire(ctx);
- if (ctx->state == SPU_STATE_SAVED) {
- /*
- * Context is about to be freed, so we can't acquire it anymore.
- */
- if (!ctx->owner)
- goto out_unlock;
- ret = spu_activate(ctx, flags);
- if (ret)
- goto out_unlock;
- }
-
- return 0;
-
- out_unlock:
- spu_release(ctx);
- return ret;
-}
-
-/**
* spu_acquire_saved - lock spu contex and make sure it is in saved state
* @ctx: spu contex to lock
*/
diff --git a/arch/powerpc/platforms/cell/spufs/file.c b/arch/powerpc/platforms/cell/spufs/file.c
index 7149726..78df905 100644
--- a/arch/powerpc/platforms/cell/spufs/file.c
+++ b/arch/powerpc/platforms/cell/spufs/file.c
@@ -572,6 +572,9 @@ void spufs_ibox_callback(struct spu *spu)
{
struct spu_context *ctx = spu->ctx;
+ if (!ctx)
+ return;
+
wake_up_all(&ctx->ibox_wq);
kill_fasync(&ctx->ibox_fasync, SIGIO, POLLIN);
}
@@ -708,6 +711,9 @@ void spufs_wbox_callback(struct spu *spu)
{
struct spu_context *ctx = spu->ctx;
+ if (!ctx)
+ return;
+
wake_up_all(&ctx->wbox_wq);
kill_fasync(&ctx->wbox_fasync, SIGIO, POLLOUT);
}
@@ -1339,6 +1345,9 @@ void spufs_mfc_callback(struct spu *spu)
{
struct spu_context *ctx = spu->ctx;
+ if (!ctx)
+ return;
+
wake_up_all(&ctx->mfc_wq);
pr_debug("%s %s\n", __FUNCTION__, spu->name);
diff --git a/arch/powerpc/platforms/cell/spufs/run.c b/arch/powerpc/platforms/cell/spufs/run.c
index 652ae13..b380050 100644
--- a/arch/powerpc/platforms/cell/spufs/run.c
+++ b/arch/powerpc/platforms/cell/spufs/run.c
@@ -41,21 +41,29 @@ void spufs_stop_callback(struct spu *spu)
spu->dar = 0;
}
-static inline int spu_stopped(struct spu_context *ctx, u32 *stat)
+int spu_stopped(struct spu_context *ctx, u32 *stat)
{
- struct spu *spu;
- u64 pte_fault;
+ u64 dsisr;
+ u32 stopped;
*stat = ctx->ops->status_read(ctx);
- spu = ctx->spu;
- if (ctx->state != SPU_STATE_RUNNABLE ||
- test_bit(SPU_SCHED_NOTIFY_ACTIVE, &ctx->sched_flags))
+ if (test_bit(SPU_SCHED_NOTIFY_ACTIVE, &ctx->sched_flags))
+ return 1;
+
+ stopped = SPU_STATUS_INVALID_INSTR | SPU_STATUS_SINGLE_STEP |
+ SPU_STATUS_STOPPED_BY_HALT | SPU_STATUS_STOPPED_BY_STOP;
+ if (*stat & stopped)
+ return 1;
+
+ dsisr = ctx->csa.dsisr;
+ if (dsisr & (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED))
return 1;
- pte_fault = ctx->csa.dsisr &
- (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED);
- return (!(*stat & SPU_STATUS_RUNNING) || pte_fault || ctx->csa.class_0_pending) ?
- 1 : 0;
+
+ if (ctx->csa.class_0_pending)
+ return 1;
+
+ return 0;
}
static int spu_setup_isolated(struct spu_context *ctx)
@@ -151,24 +159,27 @@ out:
static int spu_run_init(struct spu_context *ctx, u32 *npc)
{
- unsigned long runcntl;
+ unsigned long runcntl = SPU_RUNCNTL_RUNNABLE;
int ret;
spuctx_switch_state(ctx, SPU_UTIL_SYSTEM);
- if (ctx->flags & SPU_CREATE_ISOLATE) {
- /*
- * Force activation of spu. Isolated state assumes that
- * special loader context is loaded and running on spu.
- */
+ /*
+ * NOSCHED is synchronous scheduling with respect to the caller.
+ * The caller waits for the context to be loaded.
+ */
+ if (ctx->flags & SPU_CREATE_NOSCHED) {
if (ctx->state == SPU_STATE_SAVED) {
- spu_set_timeslice(ctx);
-
ret = spu_activate(ctx, 0);
if (ret)
return ret;
}
+ }
+ /*
+ * Apply special setup as required.
+ */
+ if (ctx->flags & SPU_CREATE_ISOLATE) {
if (!(ctx->ops->status_read(ctx) & SPU_STATUS_ISOLATED_STATE)) {
ret = spu_setup_isolated(ctx);
if (ret)
@@ -183,10 +194,11 @@ static int spu_run_init(struct spu_context *ctx, u32 *npc)
(SPU_RUNCNTL_RUNNABLE | SPU_RUNCNTL_ISOLATE);
if (runcntl == 0)
runcntl = SPU_RUNCNTL_RUNNABLE;
+ }
+ if (ctx->flags & SPU_CREATE_NOSCHED) {
spuctx_switch_state(ctx, SPU_UTIL_USER);
ctx->ops->runcntl_write(ctx, runcntl);
-
} else {
unsigned long privcntl;
@@ -194,20 +206,18 @@ static int spu_run_init(struct spu_context *ctx, u32 *npc)
privcntl = SPU_PRIVCNTL_MODE_SINGLE_STEP;
else
privcntl = SPU_PRIVCNTL_MODE_NORMAL;
- runcntl = SPU_RUNCNTL_RUNNABLE;
ctx->ops->npc_write(ctx, *npc);
ctx->ops->privcntl_write(ctx, privcntl);
+ ctx->ops->runcntl_write(ctx, runcntl);
if (ctx->state == SPU_STATE_SAVED) {
- spu_set_timeslice(ctx);
ret = spu_activate(ctx, 0);
if (ret)
return ret;
+ } else {
+ spuctx_switch_state(ctx, SPU_UTIL_USER);
}
-
- spuctx_switch_state(ctx, SPU_UTIL_USER);
- ctx->ops->runcntl_write(ctx, runcntl);
}
return 0;
@@ -218,6 +228,8 @@ static int spu_run_fini(struct spu_context *ctx, u32 *npc,
{
int ret = 0;
+ spu_del_from_rq(ctx);
+
*status = ctx->ops->status_read(ctx);
*npc = ctx->ops->npc_read(ctx);
@@ -230,26 +242,6 @@ static int spu_run_fini(struct spu_context *ctx, u32 *npc,
return ret;
}
-static int spu_reacquire_runnable(struct spu_context *ctx, u32 *npc,
- u32 *status)
-{
- int ret;
-
- ret = spu_run_fini(ctx, npc, status);
- if (ret)
- return ret;
-
- if (*status & (SPU_STATUS_STOPPED_BY_STOP | SPU_STATUS_STOPPED_BY_HALT))
- return *status;
-
- ret = spu_acquire_runnable(ctx, 0);
- if (ret)
- return ret;
-
- spuctx_switch_state(ctx, SPU_UTIL_USER);
- return 0;
-}
-
/*
* SPU syscall restarting is tricky because we violate the basic
* assumption that the signal handler is running on the interrupted
@@ -386,17 +378,8 @@ long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
if (ret)
break;
- if (unlikely(ctx->state != SPU_STATE_RUNNABLE)) {
- ret = spu_reacquire_runnable(ctx, npc, &status);
- if (ret)
- goto out2;
- continue;
- }
-
if (signal_pending(current))
ret = -ERESTARTSYS;
-
-
} while (!ret && !(status & (SPU_STATUS_STOPPED_BY_STOP |
SPU_STATUS_STOPPED_BY_HALT |
SPU_STATUS_SINGLE_STEP)));
@@ -411,7 +394,6 @@ long spufs_run_spu(struct spu_context *ctx, u32 *npc, u32 *event)
ret = spu_run_fini(ctx, npc, &status);
spu_yield(ctx);
-out2:
if ((ret == 0) ||
((ret == -ERESTARTSYS) &&
((status & SPU_STATUS_STOPPED_BY_HALT) ||
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 54b338f..2775c16 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -146,6 +146,10 @@ void spu_update_sched_info(struct spu_context *ctx)
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);
@@ -487,6 +491,13 @@ static void __spu_add_to_rq(struct spu_context *ctx)
}
}
+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;
@@ -501,10 +512,24 @@ static void __spu_del_from_rq(struct spu_context *ctx)
}
}
+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)) {
@@ -604,6 +629,7 @@ static struct spu *find_victim(struct spu_context *ctx)
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;
}
@@ -644,13 +670,10 @@ static struct spu *find_victim(struct spu_context *ctx)
victim->stats.invol_ctx_switch++;
spu->stats.invol_ctx_switch++;
+ spu_add_to_rq(victim);
+
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;
}
}
@@ -658,6 +681,48 @@ static struct spu *find_victim(struct spu_context *ctx)
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)
+{
+ spu_acquire(ctx);
+ __spu_schedule(spu, ctx);
+ spu_release(ctx);
+}
+
+static void spu_unschedule(struct spu *spu, struct spu_context *ctx)
+{
+ int node = spu->node;
+
+ mutex_lock(&cbe_spu_info[node].list_mutex);
+ cbe_spu_info[node].nr_active--;
+ 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
@@ -669,40 +734,47 @@ static struct spu *find_victim(struct spu_context *ctx)
*/
int spu_activate(struct spu_context *ctx, unsigned long flags)
{
- do {
- struct spu *spu;
+ 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;
+ /*
+ * 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) {
- int node = spu->node;
+spu_activate_top:
+ if (signal_pending(current))
+ return -ERESTARTSYS;
- mutex_lock(&cbe_spu_info[node].list_mutex);
- spu_bind_context(spu, ctx);
- cbe_spu_info[node].nr_active++;
- mutex_unlock(&cbe_spu_info[node].list_mutex);
- wake_up_all(&ctx->run_wq);
- 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) {
+ 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);
- } while (!signal_pending(current));
+ goto spu_activate_top;
+ }
- return -ERESTARTSYS;
+ spu_add_to_rq(ctx);
+
+ return 0;
}
/**
@@ -744,21 +816,17 @@ static int __spu_deactivate(struct spu_context *ctx, int force, int max_prio)
if (spu) {
new = grab_runnable_context(max_prio, spu->node);
if (new || force) {
- int node = spu->node;
-
- mutex_lock(&cbe_spu_info[node].list_mutex);
- spu_unbind_context(spu, ctx);
- spu->alloc_state = SPU_FREE;
- cbe_spu_info[node].nr_active--;
- mutex_unlock(&cbe_spu_info[node].list_mutex);
-
- ctx->stats.vol_ctx_switch++;
- spu->stats.vol_ctx_switch++;
-
- if (new)
- wake_up(&new->stop_wq);
+ spu_unschedule(spu, ctx);
+ if (new) {
+ if (new->flags & SPU_CREATE_NOSCHED)
+ wake_up(&new->stop_wq);
+ else {
+ spu_release(ctx);
+ spu_schedule(spu, new);
+ spu_acquire(ctx);
+ }
+ }
}
-
}
return new != NULL;
@@ -795,43 +863,37 @@ void spu_yield(struct spu_context *ctx)
static noinline void spusched_tick(struct spu_context *ctx)
{
+ struct spu_context *new = NULL;
+ struct spu *spu = NULL;
+ u32 status;
+
+ spu_acquire(ctx);
+
+ if (ctx->state != SPU_STATE_RUNNABLE)
+ goto out;
+ if (spu_stopped(ctx, &status))
+ goto out;
if (ctx->flags & SPU_CREATE_NOSCHED)
- return;
+ goto out;
if (ctx->policy == SCHED_FIFO)
- return;
+ goto out;
if (--ctx->time_slice)
- return;
+ goto out;
- /*
- * Unfortunately list_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_unbind_context(spu, ctx);
- ctx->stats.invol_ctx_switch++;
- spu->stats.invol_ctx_switch++;
- spu->alloc_state = SPU_FREE;
- cbe_spu_info[spu->node].nr_active--;
- 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);
+ spu = ctx->spu;
+ new = grab_runnable_context(ctx->prio + 1, spu->node);
+ if (new) {
+ spu_unschedule(spu, ctx);
+ spu_add_to_rq(ctx);
} else {
ctx->time_slice++;
}
+out:
+ spu_release(ctx);
+
+ if (new)
+ spu_schedule(spu, new);
}
/**
@@ -895,11 +957,20 @@ static int spusched_thread(void *unused)
set_current_state(TASK_INTERRUPTIBLE);
schedule();
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->ctx)
- spusched_tick(spu->ctx);
- mutex_unlock(&cbe_spu_info[node].list_mutex);
+ 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) {
+ mutex_unlock(mtx);
+ spusched_tick(ctx);
+ mutex_lock(mtx);
+ }
+ }
+ mutex_unlock(mtx);
}
}
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index eaab1b2..412de58 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -246,10 +246,11 @@ int put_spu_context(struct spu_context *ctx);
void spu_unmap_mappings(struct spu_context *ctx);
void spu_forget(struct spu_context *ctx);
-int spu_acquire_runnable(struct spu_context *ctx, unsigned long flags);
void spu_acquire_saved(struct spu_context *ctx);
void spu_release_saved(struct spu_context *ctx);
+int spu_stopped(struct spu_context *ctx, u32 * stat);
+void spu_del_from_rq(struct spu_context *ctx);
int spu_activate(struct spu_context *ctx, unsigned long flags);
void spu_deactivate(struct spu_context *ctx);
void spu_yield(struct spu_context *ctx);
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