2006. április 28. 07.34 dátummal Hareesh Nagarajan ezt írta:
> On 4/27/06, Mauricio Lin <mauriciolin2000@xxxxxxxxxxxx> wrote:
> > Since sched_clock() function is implemented differently for each arch,
> > how can I figure out the maximum value sched_clock can return?
>
> This doesn't concern your question, but I was looking at:
> sched_clock() defined in arch/i386/kernel/timers/timer_tsc.c:
>
> <definition_sans_comments>
> unsigned long long sched_clock(void)
> {
> unsigned long long this_offset;
> #ifndef CONFIG_NUMA
> if (!use_tsc)
> #endif
> return jiffies_64 * (1000000000 / HZ);
> rdtscll(this_offset);
> return cycles_2_ns(this_offset);
> }
> </definition_sans_comments>
>
> Why do we have the second return statement in the first place? It will
> never be executed.
Hmm ... if CONFIG_NUMA is not defined, the first return is executed only if
(!use_tsc) expression is true. If (!use_tsc) is false then the second return
is reached and executed.
Mulder
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