On Wed, 8 Aug 2001, Daniel Phillips wrote:
>
> write:
>
> inline int nr_running(void)
> {
> #ifdef CONFIG_SMP
> int i = 0, tot=nt_running(REALTIME_RQ);
> while (i < smp_num_cpus) {
> tot += nt_running(cpu_logical_map(i++));
> }
> return(tot);
> #else
> return nr_running;
> #endif
> }
Even more preferably, just have (in a header file)
#ifdef CONFIG_SMP
inline int nr_running(void)
{
...
}
.. other SMP cases ..
#else
#define nr_running() (__nr_running)
.. other UP cases ..
#endif
if you just cannot make an efficient function that just works for both.
No, we don't adhere to this everywhere. But we should (and largely _do_)
try to.
Having the #ifdef's outside the code tends to have two advantages:
- it makes the code much more readable, and doesn't split things up.
- you have to choose your abstraction interfaces more carefully, which in
turn tends to make for better code.
Abstraction is nice - _especially_ when you have a compiler that sees
through the abstraction and can generate code as if it wasn't there.
Linus
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This archive was generated by hypermail 2b29 : Wed Aug 15 2001 - 21:00:19 EST