linux-kernel - Re: [Cbe-oss-dev] [PATCH] Cell SPU task notification

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Message-ID: <20070117003018.GA17955@lst.de>
Date:	Wed, 17 Jan 2007 01:30:18 +0100
From:	Christoph Hellwig <hch@....de>
To:	Maynard Johnson <maynardj@...ibm.com>
Cc:	cbe-oss-dev@...abs.org, linux-kernel@...r.kernel.org,
	linuxppc-dev@...abs.org, Arnd Bergmann <arnd.bergmann@...ibm.com>
Subject: Re: [Cbe-oss-dev] [PATCH] Cell SPU task notification

Index: linux-2.6.19-rc6-arnd1+patches/arch/powerpc/platforms/cell/spufs/sched.c
===================================================================
--- linux-2.6.19-rc6-arnd1+patches.orig/arch/powerpc/platforms/cell/spufs/sched.c	2006-12-04 10:56:04.730698720 -0600
+++ linux-2.6.19-rc6-arnd1+patches/arch/powerpc/platforms/cell/spufs/sched.c	2007-01-15 16:22:31.808461448 -0600
@@ -84,15 +84,42 @@
 			    ctx ? ctx->object_id : 0, spu);
 }
 
+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_notify_already_active().
+	 */
+	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) {

	You seem to have some issues with tabs vs spaces for indentation
	here.

+			struct spu_context *ctx = spu->ctx;
+			spu->notify_active = 1;


	Please make this a bit in the sched_flags field that's added in
	the scheduler patch series I sent out.

+			wake_up_all(&ctx->stop_wq);
+			smp_wmb();
+		}
+                mutex_unlock(&spu_prio->active_mutex[node]);
+	}
+	yield();
+}

	Why do you add the yield() here?  yield is pretty much a sign
	for a bug

+void spu_notify_already_active(struct spu_context *ctx)
+{
+	struct spu *spu = ctx->spu;
+	if (!spu)
+		return;
+	spu_switch_notify(spu, ctx);
+}

	Please just call spu_switch_notify directly from the only
	caller.  Also the check for ctx->spu beeing there is not
	required if you look a the caller.


 	*stat = ctx->ops->status_read(ctx);
-	if (ctx->state != SPU_STATE_RUNNABLE)
-		return 1;
+	smp_rmb();


	What do you need the barrier for here?

-
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