Le vendredi 13 janvier 2012 à 11:45 +0000, David Laight a écrit :
> > Trying a dynamic memory allocation, and fallback on a single
> > pre-allocated bloc of memory, shared by all cpus, protected by a
> > spinlock
> ...
> > -
> > + 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);
> >
> > +
> > + 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.
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