diff options
Diffstat (limited to 'include/net/codel_impl.h')
| -rw-r--r-- | include/net/codel_impl.h | 62 |
1 files changed, 40 insertions, 22 deletions
diff --git a/include/net/codel_impl.h b/include/net/codel_impl.h index 78a27ac73070..8f26132d45b7 100644 --- a/include/net/codel_impl.h +++ b/include/net/codel_impl.h @@ -93,12 +93,17 @@ static void codel_Newton_step(struct codel_vars *vars) * CoDel control_law is t + interval/sqrt(count) * We maintain in rec_inv_sqrt the reciprocal value of sqrt(count) to avoid * both sqrt() and divide operation. + * + * Clamp the increment to at least 1 tick: a very small interval (or a + * large count) can truncate it to zero, stalling the dropping loop. */ static codel_time_t codel_control_law(codel_time_t t, codel_time_t interval, u32 rec_inv_sqrt) { - return t + reciprocal_scale(interval, rec_inv_sqrt << REC_INV_SQRT_SHIFT); + return t + max_t(u32, 1, + reciprocal_scale(interval, + rec_inv_sqrt << REC_INV_SQRT_SHIFT)); } static bool codel_should_drop(const struct sk_buff *skb, @@ -120,10 +125,10 @@ static bool codel_should_drop(const struct sk_buff *skb, } skb_len = skb_len_func(skb); - vars->ldelay = now - skb_time_func(skb); + WRITE_ONCE(vars->ldelay, now - skb_time_func(skb)); if (unlikely(skb_len > stats->maxpacket)) - stats->maxpacket = skb_len; + WRITE_ONCE(stats->maxpacket, skb_len); if (codel_time_before(vars->ldelay, params->target) || *backlog <= params->mtu) { @@ -154,11 +159,13 @@ static struct sk_buff *codel_dequeue(void *ctx, codel_skb_dequeue_t dequeue_func) { struct sk_buff *skb = dequeue_func(vars, ctx); + unsigned int drops = 0; codel_time_t now; bool drop; if (!skb) { - vars->dropping = false; + vars->first_above_time = 0; + WRITE_ONCE(vars->dropping, false); return skb; } now = codel_get_time(); @@ -167,7 +174,7 @@ static struct sk_buff *codel_dequeue(void *ctx, if (vars->dropping) { if (!drop) { /* sojourn time below target - leave dropping state */ - vars->dropping = false; + WRITE_ONCE(vars->dropping, false); } else if (codel_time_after_eq(now, vars->drop_next)) { /* It's time for the next drop. Drop the current * packet and dequeue the next. The dequeue might @@ -179,16 +186,26 @@ static struct sk_buff *codel_dequeue(void *ctx, */ while (vars->dropping && codel_time_after_eq(now, vars->drop_next)) { - vars->count++; /* dont care of possible wrap - * since there is no more divide - */ + if (++drops > CODEL_MAX_DROPS_PER_DEQUEUE) { + /* fell far behind the schedule */ + WRITE_ONCE(vars->drop_next, + codel_control_law(now, + params->interval, + vars->rec_inv_sqrt)); + break; + } + /* dont care of possible wrap + * since there is no more divide. + */ + WRITE_ONCE(vars->count, vars->count + 1); codel_Newton_step(vars); if (params->ecn && INET_ECN_set_ce(skb)) { - stats->ecn_mark++; - vars->drop_next = + WRITE_ONCE(stats->ecn_mark, + stats->ecn_mark + 1); + WRITE_ONCE(vars->drop_next, codel_control_law(vars->drop_next, params->interval, - vars->rec_inv_sqrt); + vars->rec_inv_sqrt)); goto end; } stats->drop_len += skb_len_func(skb); @@ -201,13 +218,13 @@ static struct sk_buff *codel_dequeue(void *ctx, skb_time_func, backlog, now)) { /* leave dropping state */ - vars->dropping = false; + WRITE_ONCE(vars->dropping, false); } else { /* and schedule the next drop */ - vars->drop_next = + WRITE_ONCE(vars->drop_next, codel_control_law(vars->drop_next, params->interval, - vars->rec_inv_sqrt); + vars->rec_inv_sqrt)); } } } @@ -215,7 +232,7 @@ static struct sk_buff *codel_dequeue(void *ctx, u32 delta; if (params->ecn && INET_ECN_set_ce(skb)) { - stats->ecn_mark++; + WRITE_ONCE(stats->ecn_mark, stats->ecn_mark + 1); } else { stats->drop_len += skb_len_func(skb); drop_func(skb, ctx); @@ -226,7 +243,7 @@ static struct sk_buff *codel_dequeue(void *ctx, stats, skb_len_func, skb_time_func, backlog, now); } - vars->dropping = true; + WRITE_ONCE(vars->dropping, true); /* if min went above target close to when we last went below it * assume that the drop rate that controlled the queue on the * last cycle is a good starting point to control it now. @@ -235,19 +252,20 @@ static struct sk_buff *codel_dequeue(void *ctx, if (delta > 1 && codel_time_before(now - vars->drop_next, 16 * params->interval)) { - vars->count = delta; + WRITE_ONCE(vars->count, delta); /* we dont care if rec_inv_sqrt approximation * is not very precise : * Next Newton steps will correct it quadratically. */ codel_Newton_step(vars); } else { - vars->count = 1; + WRITE_ONCE(vars->count, 1); vars->rec_inv_sqrt = ~0U >> REC_INV_SQRT_SHIFT; } - vars->lastcount = vars->count; - vars->drop_next = codel_control_law(now, params->interval, - vars->rec_inv_sqrt); + WRITE_ONCE(vars->lastcount, vars->count); + WRITE_ONCE(vars->drop_next, + codel_control_law(now, params->interval, + vars->rec_inv_sqrt)); } end: if (skb && codel_time_after(vars->ldelay, params->ce_threshold)) { @@ -261,7 +279,7 @@ end: params->ce_threshold_selector)); } if (set_ce && INET_ECN_set_ce(skb)) - stats->ce_mark++; + WRITE_ONCE(stats->ce_mark, stats->ce_mark + 1); } return skb; } |