Re: Patch 2/6 introduce helper infrastructure

[Andi Kleen]

Arjan van de Ven <arjan@xxxxxxxxxxxxx> writes:
> +unsigned int get_random_int(void)
> +{
> +	static unsigned int val = 0;
> +
> +	val += current->pid + jiffies;

Shouldn't there be some kind of locking for this? It's random,
but still random corruption sounds a bit too random.

Also you probably have a very hot cache line here, which
may hurt on the bigger machines.

I think it would be better to just get a global random number
for each mm as it is created and then run a fast PRNG with that
state. Maybe even make it per task to improve performance on
multithreaded programs. Or alternatively per cpu state with
different starting points.

-Andi
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