Messages in this thread | | | Date | Thu, 22 Feb 2007 11:00:16 +0800 | From | "Dong Feng" <> | Subject | PREEMP_ACTIVE in cond_resched |
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cond_resched() checks and conditionally sets PREEMPT_ACTIVE flag for the current task. The comments says,
/* * The BKS might be reacquired before we have dropped * PREEMPT_ACTIVE, which could trigger a second * cond_resched() call. */
My understanding is that cond_resched() would be indirectly invoked twice recursively, through the following path,
cond_resched() -> schedule() -> reacquire_kernel_lock() -> down() -> might_sleep() -> might_resched() -> cond_resched().
However, the above path is possible only in a voluntary-preemptive kernel. In a full-preemptive kernel, I do not find any possible path to cause recursive cond_resched(). Does that mean we can actually remove the check and setting of PREEMPT_ACTIVE for a full-preemptive kernel? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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