Can you also test the following patch?
I think there's a bug in b44 that is doesn't properly discard
shared IRQs, so it might possibly generate a NAPI storm, dunno.
Worth a try.

Index: linux-2.6.22-rc3/drivers/net/b44.c
===================================================================
--- linux-2.6.22-rc3.orig/drivers/net/b44.c	2007-05-27 23:01:44.000000000 +0200
+++ linux-2.6.22-rc3/drivers/net/b44.c	2007-05-28 12:48:27.000000000 +0200
@@ -911,6 +911,8 @@ static irqreturn_t b44_interrupt(int irq
 	spin_lock(&bp->lock);
 
 	istat = br32(bp, B44_ISTAT);
+	if (istat == 0xFFFFFFFF)
+		goto out; /* Shared IRQ not for us */
 	imask = br32(bp, B44_IMASK);
 
 	/* The interrupt mask register controls which interrupt bits
@@ -942,6 +944,7 @@ irq_ack:
 		bw32(bp, B44_ISTAT, istat);
 		br32(bp, B44_ISTAT);
 	}
+out:
 	spin_unlock(&bp->lock);
 	return IRQ_RETVAL(handled);
 }


-- 
Greetings Michael.
-
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