[PATCH] spufs: Improved SPU preemptability.
This patch makes it easier to preempt an SPU context by
having the scheduler hold ctx->state_sema for much shorter
periods of time.
As part of this restructuring, the control logic for the "run"
operation is moved from arch/ppc64/kernel/spu_base.c to
fs/spufs/file.c. Of course the base retains "bottom half"
handlers for class{0,1} irqs. The new run loop will re-acquire
an SPU if preempted.
From: Mark Nutter <mnutter@us.ibm.com>
Signed-off-by: Arnd Bergmann <arndb@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/platforms/cell/spufs/file.c b/arch/powerpc/platforms/cell/spufs/file.c
index 0fe1fec..af5adc3 100644
--- a/arch/powerpc/platforms/cell/spufs/file.c
+++ b/arch/powerpc/platforms/cell/spufs/file.c
@@ -25,6 +25,7 @@
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/poll.h>
+#include <linux/ptrace.h>
#include <asm/io.h>
#include <asm/semaphore.h>
@@ -540,26 +541,122 @@
.read = spufs_wbox_stat_read,
};
-long spufs_run_spu(struct file *file, struct spu_context *ctx,
- u32 *npc, u32 *status)
+/* interrupt-level stop callback function. */
+void spufs_stop_callback(struct spu *spu)
+{
+ struct spu_context *ctx = spu->ctx;
+
+ wake_up_all(&ctx->stop_wq);
+}
+
+static inline int spu_stopped(struct spu_context *ctx, u32 * stat)
+{
+ struct spu *spu;
+ u64 pte_fault;
+
+ *stat = ctx->ops->status_read(ctx);
+ if (ctx->state != SPU_STATE_RUNNABLE)
+ return 1;
+ spu = ctx->spu;
+ pte_fault = spu->dsisr &
+ (MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED);
+ return (!(*stat & 0x1) || pte_fault || spu->class_0_pending) ? 1 : 0;
+}
+
+static inline int spu_run_init(struct spu_context *ctx, u32 * npc,
+ u32 * status)
{
int ret;
- ret = spu_acquire_runnable(ctx);
- if (ret)
+ if ((ret = spu_acquire_runnable(ctx)) != 0)
+ return ret;
+ ctx->ops->npc_write(ctx, *npc);
+ ctx->ops->runcntl_write(ctx, SPU_RUNCNTL_RUNNABLE);
+ return 0;
+}
+
+static inline int spu_run_fini(struct spu_context *ctx, u32 * npc,
+ u32 * status)
+{
+ int ret = 0;
+
+ *status = ctx->ops->status_read(ctx);
+ *npc = ctx->ops->npc_read(ctx);
+ spu_release(ctx);
+
+ if (signal_pending(current))
+ ret = -ERESTARTSYS;
+ if (unlikely(current->ptrace & PT_PTRACED)) {
+ if ((*status & SPU_STATUS_STOPPED_BY_STOP)
+ && (*status >> SPU_STOP_STATUS_SHIFT) == 0x3fff) {
+ force_sig(SIGTRAP, current);
+ ret = -ERESTARTSYS;
+ }
+ }
+ return ret;
+}
+
+static inline int spu_reacquire_runnable(struct spu_context *ctx, u32 *npc,
+ u32 *status)
+{
+ int ret;
+
+ if ((ret = spu_run_fini(ctx, npc, status)) != 0)
+ return ret;
+ if (*status & (SPU_STATUS_STOPPED_BY_STOP |
+ SPU_STATUS_STOPPED_BY_HALT)) {
+ return *status;
+ }
+ if ((ret = spu_run_init(ctx, npc, status)) != 0)
+ return ret;
+ return 0;
+}
+
+static inline int spu_process_events(struct spu_context *ctx)
+{
+ struct spu *spu = ctx->spu;
+ u64 pte_fault = MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED;
+ int ret = 0;
+
+ if (spu->dsisr & pte_fault)
+ ret = spu_irq_class_1_bottom(spu);
+ if (spu->class_0_pending)
+ ret = spu_irq_class_0_bottom(spu);
+ if (!ret && signal_pending(current))
+ ret = -ERESTARTSYS;
+ return ret;
+}
+
+long spufs_run_spu(struct file *file, struct spu_context *ctx,
+ u32 * npc, u32 * status)
+{
+ int ret;
+
+ if ((ret = spu_run_init(ctx, npc, status)) != 0)
return ret;
- ctx->ops->npc_write(ctx, *npc);
+ do {
+ ret = spufs_wait(ctx->stop_wq, spu_stopped(ctx, status));
+ if (unlikely(ret))
+ break;
+ if (unlikely(ctx->state != SPU_STATE_RUNNABLE)) {
+ ret = spu_reacquire_runnable(ctx, npc, status);
+ if (ret) {
+ return ret;
+ }
+ continue;
+ }
+ ret = spu_process_events(ctx);
- ret = spu_run(ctx->spu);
+ } while (!ret && !(*status & (SPU_STATUS_STOPPED_BY_STOP |
+ SPU_STATUS_STOPPED_BY_HALT)));
+ ctx->ops->runcntl_stop(ctx);
+ ret = spu_run_fini(ctx, npc, status);
if (!ret)
- ret = ctx->ops->status_read(ctx);
-
- *npc = ctx->ops->npc_read(ctx);
-
- spu_release(ctx);
+ ret = *status;
spu_yield(ctx);
+
return ret;
}