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Commit c16632ba authored by Corrado Zoccolo's avatar Corrado Zoccolo Committed by Jens Axboe
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cfq-iosched: cleanup unreachable code 



cfq_should_idle returns false for no-idle queues that are not the last,
so the control flow will never reach the removed code in a state that
satisfies the if condition.
The unreachable code was added to emulate previous cfq behaviour for
non-NCQ rotational devices. My tests show that even without it, the
performances and fairness are comparable with previous cfq, thanks to
the fact that all seeky queues are grouped together, and that we idle at
the end of the tree.

Signed-off-by: default avatarCorrado Zoccolo <czoccolo@gmail.com>
Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 2d4dc890

block/cfq-iosched.c

+0 −13
Original line number Original line Diff line number Diff line
@@ -1269,19 +1269,6 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd) 
	cfq_mark_cfqq_wait_request(cfqq);

	cfq_mark_cfqq_wait_request(cfqq);





	sl = cfqd->cfq_slice_idle;

	sl = cfqd->cfq_slice_idle;

	/* are we servicing noidle tree, and there are more queues?

	 * non-rotational or NCQ: no idle

	 * non-NCQ rotational : very small idle, to allow

	 *     fair distribution of slice time for a process doing back-to-back

	 *     seeks.

	 */

	if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&

	    service_tree_for(cfqd->serving_prio, SYNC_NOIDLE_WORKLOAD, cfqd)

		->count > 0) {

		if (blk_queue_nonrot(cfqd->queue) || cfqd->hw_tag)

			return;

		sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));

	}





	mod_timer(&cfqd->idle_slice_timer, jiffies + sl);

	mod_timer(&cfqd->idle_slice_timer, jiffies + sl);

	cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);

	cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);