Re: delay_tsc(): inefficient delay loop (2.6.16-mm1)

[Edgar Toernig]

Andreas Mohr wrote:
>
>  	rdtscl(bclock);
> +	/* offset with bclock to have very simple comparison below */
> +	loops += bclock;
>  	do {
>  		rep_nop();
>  		rdtscl(now);
> -	} while ((now-bclock) < loops);
> +	} while (now < loops);
>  }

Hehe, optimizing delay loops *g*  But your optimization is
wrong.  'loops+bclock' and/or 'now' is likely to wrap around
and then the test condition becomes bogus.

Ciao, ET.
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