Le vendredi 13 janvier 2012 à 11:45 +0000, David Laight a écrit :

quoted

Trying a dynamic memory allocation, and fallback on a single
pre-allocated bloc of memory, shared by all cpus, protected by a
spinlock

...

quoted

-
+	static u64 msg_schedule[80];
+	static DEFINE_SPINLOCK(msg_schedule_lock);
 	int i;
-	u64 *W = get_cpu_var(msg_schedule);
+	u64 *W = kzalloc(sizeof(msg_schedule), GFP_ATOMIC |

__GFP_NOWARN);

quoted

 
+	
+	if (!W) {
+		spin_lock_bh(&msg_schedule_lock);
+		W = msg_schedule;
+	}

If this code can be called from an ISR is the kmalloc()
call safe?

Yes, obviously, kmalloc() is IRQ safe.

If the above is safe, wouldn't it be better to:
1) try to use the static buffer
2) try to kalloc() a buffer
3) spinwait for the static buffer to be free

No idea of what you mean, and why you think its better.

kmalloc() propably can give us a block already hot in cpu cache.