On Mon, 08 Dec 2008 09:05:04 +0100 Eric Dumazet <dada1@xxxxxxxxxxxxx> wrote:
> Andrew Morton a __crit :
> > On Sun, 07 Dec 2008 19:30:10 +0100 Eric Dumazet <dada1@xxxxxxxxxxxxx> wrote:
> >
> >>> Do
> >>>
> >>> $EDITOR $(grep -l hotcpu_notifier */*.c)
> >>>
> >>> and you'll see lots of code gets it right, and lots of code gets it wrong.
> >> I see nothing interesting, I must be blind.
> >>
> >> lib/percpu_counter.c: In function 'percpu_counter_startup':
> >> lib/percpu_counter.c:158: error: 'percpu_counter_hotcpu_callback' undeclared (first use in this function)
> >> lib/percpu_counter.c:158: error: (Each undeclared identifier is reported only once
> >> lib/percpu_counter.c:158: error: for each function it appears in.)
> >> make[1]: *** [lib/percpu_counter.o] Error 1
> >
> > Perhaps you still had percpu_counter_hotcpu_callback inside #ifdef.
> >
> > That a look at kernel/workqueue.c, fs/buffer.c. No #ifdef CONFIG_HOTPLUG_CPU
> > needed at all.
>
> We still need some #ifdef or we also must also delete them around "struct list_head list"
> in include/linux/percpu_counter.h and grow struct percpu_counter.
>
> lib/percpu_counter.c: In function 'percpu_counter_hotcpu_callback':
> lib/percpu_counter.c:137: error: 'struct percpu_counter' has no member named 'list'
> lib/percpu_counter.c:137: warning: type defaults to 'int' in declaration of '__mptr'
> lib/percpu_counter.c:137: warning: initialization from incompatible pointer type
> ...
>
Yes, this conditionality:
struct percpu_counter {
spinlock_t lock;
s64 count;
#ifdef CONFIG_HOTPLUG_CPU
struct list_head list; /* All percpu_counters are on a list */
#endif
s32 *counters;
};
mucked up our nice scheme. Oh well.
> +static void compute_batch_value(void)
> +{
> + int nr = num_online_cpus();
> +
> + percpu_counter_batch = max(32, nr*2);
> +}
> +
> static int __cpuinit percpu_counter_hotcpu_callback(struct notifier_block *nb,
> unsigned long action, void *hcpu)
> {
> +#ifdef CONFIG_HOTPLUG_CPU
> unsigned int cpu;
> struct percpu_counter *fbc;
>
> + compute_batch_value();
> if (action != CPU_DEAD)
> return NOTIFY_OK;
>
> @@ -137,13 +146,14 @@ static int __cpuinit percpu_counter_hotcpu_callback(struct notifier_block *nb,
> spin_unlock_irqrestore(&fbc->lock, flags);
> }
> mutex_unlock(&percpu_counters_lock);
> +#endif
> return NOTIFY_OK;
> }
>
> static int __init percpu_counter_startup(void)
> {
> + compute_batch_value();
> hotcpu_notifier(percpu_counter_hotcpu_callback, 0);
> return 0;
> }
> module_init(percpu_counter_startup);
compute_batch_value() can be __cpuinit, but I think we're close enough
here ;)
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