On Monday 29 January 2007 20:48, Maynard Johnson wrote:
Subject: Enable SPU switch notification to detect currently active SPU tasks.
From: Maynard Johnson <[email protected]>
This patch adds to the capability of spu_switch_event_register so that the
caller is also notified of currently active SPU tasks. It also exports
spu_switch_event_register and spu_switch_event_unregister.
Signed-off-by: Maynard Johnson <[email protected]>
I looked through it again, and think I found a serious bug, but that
should be easy enough to solve:
+static void notify_spus_active(void)
+{
+ int node;
+ /* Wake up the active spu_contexts. When the awakened processes
+ * sees their notify_active flag is set, they will call
+ * spu_switch_notify();
+ */
+ for (node = 0; node < MAX_NUMNODES; node++) {
+ struct spu *spu;
+ mutex_lock(&spu_prio->active_mutex[node]);
+ list_for_each_entry(spu, &spu_prio->active_list[node], list) {
+ struct spu_context *ctx = spu->ctx;
[side note]
There is a small whitespace breakage in here, please make sure you always
use tabs for indenting, not space characters.
[/side note]
@@ -45,9 +45,10 @@
u64 pte_fault;
*stat = ctx->ops->status_read(ctx);
- if (ctx->state != SPU_STATE_RUNNABLE)
- return 1;
+
spu = ctx->spu;
+ if (ctx->state != SPU_STATE_RUNNABLE || spu->notify_active)
+ return 1;
pte_fault = spu->dsisr &
(MFC_DSISR_PTE_NOT_FOUND | MFC_DSISR_ACCESS_DENIED);
return (!(*stat & 0x1) || pte_fault || spu->class_0_pending) ? 1 : 0;
@@ -305,6 +306,7 @@
u32 *npc, u32 *event)
{
int ret;
+ struct spu * spu;
u32 status;
if (down_interruptible(&ctx->run_sema))
@@ -318,8 +320,16 @@
do {
ret = spufs_wait(ctx->stop_wq, spu_stopped(ctx, &status));
+ spu = ctx->spu;
if (unlikely(ret))
break;
+ if (unlikely(spu->notify_active)) {
+ spu->notify_active = 0;
+ if (!(status & SPU_STATUS_STOPPED_BY_STOP)) {
+ spu_switch_notify(spu, ctx);
+ continue;
+ }
+ }
This is before spu_reacquire_runnable, so in case the spu got
preempted at the same time when oprofile was enabled, ctx->spu
is NULL, and you can't load the notify_active flag from it.
On solution would be to move the notify_active flag from ctx->spu
into ctx itself, but maybe there are other ways to solve this.
