cfq-iosched: don't check cfqg in choose_service_tree() (7278c9c1) · Commits · 戴 / test

When cfq_choose_cfqg() is called in select_queue(), there must be at least one backlogged CFQ queue waiting for dispatching, hence there must be at least one backlogged CFQ group on service tree. So we never call choose_service_tree() with cfqg == NULL. Signed-off-by:

Gui Jianfeng <guijianfeng@cn.fujitsu.com> Reviewed-by:

Jeff Moyer <jmoyer@redhat.com> Acked-by:

Vivek Goyal <vgoyal@redhat.com> Signed-off-by:

Jens Axboe <jaxboe@fusionio.com>

block/cfq-iosched.c

+0 −6

Original line number	Original line	Diff line number	Diff line
	@@ -2103,12 +2103,6 @@ static void choose_service_tree(struct cfq_data cfqd, struct cfq_group cfqg)
	unsigned group_slice;		unsigned group_slice;
	enum wl_prio_t original_prio = cfqd->serving_prio;		enum wl_prio_t original_prio = cfqd->serving_prio;

	if (!cfqg) {
	cfqd->serving_prio = IDLE_WORKLOAD;
	cfqd->workload_expires = jiffies + 1;
	return;
	}

	/* Choose next priority. RT > BE > IDLE */		/* Choose next priority. RT > BE > IDLE */
	if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))		if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
	cfqd->serving_prio = RT_WORKLOAD;		cfqd->serving_prio = RT_WORKLOAD;

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