On Sat, Nov 17, 2007 at 04:45:42PM -0800, David Miller wrote:
>
> Herbert, you asked about just nop'ing out cond_resched() when we're
> doing real preemption.
>
> A lot of code goes:
>
> if (need_resched()) {
> /* drop some locks, etc. */
> cond_resched();
> /* reacquire locks, etc. */
> }
>
> So it has to do something even with real preemption enabled.
Actually that shouldn't be necessary. Because things like spin_unlock
does preempt_enable which in turn does:
#define preempt_enable() \
do { \
preempt_enable_no_resched(); \
barrier(); \
preempt_check_resched(); \
} while (0)
when CONFIG_PREEMPT is enabled. So at least in this case the
cond_resched call is superfluous.
Cheers,
--
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Email: Herbert Xu ~{PmV>HI~} <[EMAIL PROTECTED]>
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