Re: [PATCH][resubmit] x86: enable preemption in delay

[Andi Kleen]

>  static void delay_tsc(unsigned long loops)
>  {
> -	unsigned long bclock, now;
> +	unsigned prev, prev_1, now;
> +	unsigned left = loops;
> +	unsigned prev_cpu, cpu;
> +
> +	preempt_disable();
> +	rdtscl(prev);


The unsigneds should be probably u64  and the rdtsc rdtscll.
Otherwise this will all overflow for longer waits on a very
fast systems (e.g. a 5Ghz system wraps 32bit in ~1.1 seconds)
Normally such delays shouldn't be that long, but why risk
overflow even in extreme cases?

-Andi
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