5  * Codel - The Controlled-Delay Active Queue Management algorithm
7  *  Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com>
8  *  Copyright (C) 2011-2012 Van Jacobson <van@pollere.net>
22  *    derived from this software without specific prior written permission.
25  * software may be distributed under the terms of the GNU General
29  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
39  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
56 	params->interval = MS2TIME(100);  in codel_params_init()
57 	params->target = MS2TIME(5);  in codel_params_init()
58 	params->ce_threshold = CODEL_DISABLED_THRESHOLD;  in codel_params_init()
59 	params->ce_threshold_mask = 0;  in codel_params_init()
60 	params->ce_threshold_selector = 0;  in codel_params_init()
61 	params->ecn = false;  in codel_params_init()
71 	stats->maxpacket = 0;  in codel_stats_init()
76  * new_invsqrt = (invsqrt / 2) * (3 - count * invsqrt^2)
82 	u32 invsqrt = ((u32)vars->rec_inv_sqrt) << REC_INV_SQRT_SHIFT;  in codel_Newton_step()
84 	u64 val = (3LL << 32) - ((u64)vars->count * invsqrt2);  in codel_Newton_step()
87 	val = (val * invsqrt) >> (32 - 2 + 1);  in codel_Newton_step()
89 	vars->rec_inv_sqrt = val >> REC_INV_SQRT_SHIFT;  in codel_Newton_step()
118 		vars->first_above_time = 0;  in codel_should_drop()
123 	vars->ldelay = now - skb_time_func(skb);  in codel_should_drop()
125 	if (unlikely(skb_len > stats->maxpacket))  in codel_should_drop()
126 		stats->maxpacket = skb_len;  in codel_should_drop()
128 	if (codel_time_before(vars->ldelay, params->target) ||  in codel_should_drop()
129 	    *backlog <= params->mtu) {  in codel_should_drop()
130 		/* went below - stay below for at least interval */  in codel_should_drop()
131 		vars->first_above_time = 0;  in codel_should_drop()
135 	if (vars->first_above_time == 0) {  in codel_should_drop()
139 		vars->first_above_time = now + params->interval;  in codel_should_drop()
140 	} else if (codel_time_after(now, vars->first_above_time)) {  in codel_should_drop()
161 		vars->dropping = false;  in codel_dequeue()
167 	if (vars->dropping) {  in codel_dequeue()
169 			/* sojourn time below target - leave dropping state */  in codel_dequeue()
170 			vars->dropping = false;  in codel_dequeue()
171 		} else if (codel_time_after_eq(now, vars->drop_next)) {  in codel_dequeue()
180 			while (vars->dropping &&  in codel_dequeue()
181 			       codel_time_after_eq(now, vars->drop_next)) {  in codel_dequeue()
182 				vars->count++; /* dont care of possible wrap  in codel_dequeue()
186 				if (params->ecn && INET_ECN_set_ce(skb)) {  in codel_dequeue()
187 					stats->ecn_mark++;  in codel_dequeue()
188 					vars->drop_next =  in codel_dequeue()
189 						codel_control_law(vars->drop_next,  in codel_dequeue()
190 								  params->interval,  in codel_dequeue()
191 								  vars->rec_inv_sqrt);  in codel_dequeue()
194 				stats->drop_len += skb_len_func(skb);  in codel_dequeue()
196 				stats->drop_count++;  in codel_dequeue()
204 					vars->dropping = false;  in codel_dequeue()
207 					vars->drop_next =  in codel_dequeue()
208 						codel_control_law(vars->drop_next,  in codel_dequeue()
209 								  params->interval,  in codel_dequeue()
210 								  vars->rec_inv_sqrt);  in codel_dequeue()
217 		if (params->ecn && INET_ECN_set_ce(skb)) {  in codel_dequeue()
218 			stats->ecn_mark++;  in codel_dequeue()
220 			stats->drop_len += skb_len_func(skb);  in codel_dequeue()
222 			stats->drop_count++;  in codel_dequeue()
229 		vars->dropping = true;  in codel_dequeue()
231 		 * assume that the drop rate that controlled the queue on the  in codel_dequeue()
234 		delta = vars->count - vars->lastcount;  in codel_dequeue()
236 		    codel_time_before(now - vars->drop_next,  in codel_dequeue()
237 				      16 * params->interval)) {  in codel_dequeue()
238 			vars->count = delta;  in codel_dequeue()
245 			vars->count = 1;  in codel_dequeue()
246 			vars->rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT;  in codel_dequeue()
248 		vars->lastcount = vars->count;  in codel_dequeue()
249 		vars->drop_next = codel_control_law(now, params->interval,  in codel_dequeue()
250 						    vars->rec_inv_sqrt);  in codel_dequeue()
253 	if (skb && codel_time_after(vars->ldelay, params->ce_threshold)) {  in codel_dequeue()
256 		if (params->ce_threshold_mask) {  in codel_dequeue()
260 				  (((u8)dsfield & params->ce_threshold_mask) ==  in codel_dequeue()
261 				   params->ce_threshold_selector));  in codel_dequeue()
264 			stats->ce_mark++;  in codel_dequeue()