codel: refine one condition to avoid a nul rec_inv_sqrt
One condition before codel_Newton_step() was not good if we never left the dropping state for a flow. As a result rec_inv_sqrt was 0, instead of the ~0 initial value. codel control law was then set to a very aggressive mode, dropping many packets before reaching 'target' and recovering from this problem. To keep codel_vars_init() as efficient as possible, refine the condition to make sure rec_inv_sqrt initial value is correct Many thanks to Anton Mich for discovering the issue and suggesting a fix. Reported-by: Anton Mich <lp2s1h@gmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
55461ddbcb
commit
2359a47671
|
@ -305,6 +305,8 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
|
||||||
}
|
}
|
||||||
}
|
}
|
||||||
} else if (drop) {
|
} else if (drop) {
|
||||||
|
u32 delta;
|
||||||
|
|
||||||
if (params->ecn && INET_ECN_set_ce(skb)) {
|
if (params->ecn && INET_ECN_set_ce(skb)) {
|
||||||
stats->ecn_mark++;
|
stats->ecn_mark++;
|
||||||
} else {
|
} else {
|
||||||
|
@ -320,9 +322,11 @@ static struct sk_buff *codel_dequeue(struct Qdisc *sch,
|
||||||
* assume that the drop rate that controlled the queue on the
|
* assume that the drop rate that controlled the queue on the
|
||||||
* last cycle is a good starting point to control it now.
|
* last cycle is a good starting point to control it now.
|
||||||
*/
|
*/
|
||||||
if (codel_time_before(now - vars->drop_next,
|
delta = vars->count - vars->lastcount;
|
||||||
|
if (delta > 1 &&
|
||||||
|
codel_time_before(now - vars->drop_next,
|
||||||
16 * params->interval)) {
|
16 * params->interval)) {
|
||||||
vars->count = (vars->count - vars->lastcount) | 1;
|
vars->count = delta;
|
||||||
/* we dont care if rec_inv_sqrt approximation
|
/* we dont care if rec_inv_sqrt approximation
|
||||||
* is not very precise :
|
* is not very precise :
|
||||||
* Next Newton steps will correct it quadratically.
|
* Next Newton steps will correct it quadratically.
|
||||||
|
|
Reference in New Issue