From ef87979c273a2348430648ad1d5c2a5e5df50b6e Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Tue, 22 Sep 2009 19:41:43 +0000 Subject: [PATCH] pktgen: better scheduler friendliness Previous update did not resched in inner loop causing watchdogs. Rewrite inner loop to: * account for delays better with less clock calls * more accurate timing of delay: - only delay if packet was successfully sent - if delay is 100ns and it takes 10ns to build packet then account for that * use wait_event_interruptible_timeout rather than open coding it. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/core/pktgen.c | 151 ++++++++++++++++++++++------------------------ 1 file changed, 72 insertions(+), 79 deletions(-) diff --git a/net/core/pktgen.c b/net/core/pktgen.c index 475f52530b6c..4d11c28ca8ca 100644 --- a/net/core/pktgen.c +++ b/net/core/pktgen.c @@ -2104,7 +2104,7 @@ static void pktgen_setup_inject(struct pktgen_dev *pkt_dev) static void spin(struct pktgen_dev *pkt_dev, ktime_t spin_until) { - ktime_t start; + ktime_t start_time, end_time; s32 remaining; struct hrtimer_sleeper t; @@ -2115,7 +2115,7 @@ static void spin(struct pktgen_dev *pkt_dev, ktime_t spin_until) if (remaining <= 0) return; - start = ktime_now(); + start_time = ktime_now(); if (remaining < 100) udelay(remaining); /* really small just spin */ else { @@ -2134,7 +2134,10 @@ static void spin(struct pktgen_dev *pkt_dev, ktime_t spin_until) } while (t.task && pkt_dev->running && !signal_pending(current)); __set_current_state(TASK_RUNNING); } - pkt_dev->idle_acc += ktime_to_ns(ktime_sub(ktime_now(), start)); + end_time = ktime_now(); + + pkt_dev->idle_acc += ktime_to_ns(ktime_sub(end_time, start_time)); + pkt_dev->next_tx = ktime_add_ns(end_time, pkt_dev->delay); } static inline void set_pkt_overhead(struct pktgen_dev *pkt_dev) @@ -3364,19 +3367,29 @@ static void pktgen_rem_thread(struct pktgen_thread *t) mutex_unlock(&pktgen_thread_lock); } -static void idle(struct pktgen_dev *pkt_dev) +static void pktgen_resched(struct pktgen_dev *pkt_dev) { ktime_t idle_start = ktime_now(); + schedule(); + pkt_dev->idle_acc += ktime_to_ns(ktime_sub(ktime_now(), idle_start)); +} - if (need_resched()) - schedule(); - else - cpu_relax(); +static void pktgen_wait_for_skb(struct pktgen_dev *pkt_dev) +{ + ktime_t idle_start = ktime_now(); + while (atomic_read(&(pkt_dev->skb->users)) != 1) { + if (signal_pending(current)) + break; + + if (need_resched()) + pktgen_resched(pkt_dev); + else + cpu_relax(); + } pkt_dev->idle_acc += ktime_to_ns(ktime_sub(ktime_now(), idle_start)); } - static void pktgen_xmit(struct pktgen_dev *pkt_dev) { struct net_device *odev = pkt_dev->odev; @@ -3386,36 +3399,21 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev) u16 queue_map; int ret; - if (pkt_dev->delay) { - spin(pkt_dev, pkt_dev->next_tx); - - /* This is max DELAY, this has special meaning of - * "never transmit" - */ - if (pkt_dev->delay == ULLONG_MAX) { - pkt_dev->next_tx = ktime_add_ns(ktime_now(), ULONG_MAX); - return; - } - } - - if (!pkt_dev->skb) { - set_cur_queue_map(pkt_dev); - queue_map = pkt_dev->cur_queue_map; - } else { - queue_map = skb_get_queue_mapping(pkt_dev->skb); + /* If device is offline, then don't send */ + if (unlikely(!netif_running(odev) || !netif_carrier_ok(odev))) { + pktgen_stop_device(pkt_dev); + return; } - txq = netdev_get_tx_queue(odev, queue_map); - /* Did we saturate the queue already? */ - if (netif_tx_queue_stopped(txq) || netif_tx_queue_frozen(txq)) { - /* If device is down, then all queues are permnantly frozen */ - if (netif_running(odev)) - idle(pkt_dev); - else - pktgen_stop_device(pkt_dev); + /* This is max DELAY, this has special meaning of + * "never transmit" + */ + if (unlikely(pkt_dev->delay == ULLONG_MAX)) { + pkt_dev->next_tx = ktime_add_ns(ktime_now(), ULONG_MAX); return; } + /* If no skb or clone count exhausted then get new one */ if (!pkt_dev->skb || (pkt_dev->last_ok && ++pkt_dev->clone_count >= pkt_dev->clone_skb)) { /* build a new pkt */ @@ -3434,54 +3432,45 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev) pkt_dev->clone_count = 0; /* reset counter */ } - /* fill_packet() might have changed the queue */ + if (pkt_dev->delay && pkt_dev->last_ok) + spin(pkt_dev, pkt_dev->next_tx); + queue_map = skb_get_queue_mapping(pkt_dev->skb); txq = netdev_get_tx_queue(odev, queue_map); __netif_tx_lock_bh(txq); - if (unlikely(netif_tx_queue_stopped(txq) || netif_tx_queue_frozen(txq))) - pkt_dev->last_ok = 0; - else { - atomic_inc(&(pkt_dev->skb->users)); + atomic_inc(&(pkt_dev->skb->users)); - retry_now: + if (unlikely(netif_tx_queue_stopped(txq) || netif_tx_queue_frozen(txq))) + ret = NETDEV_TX_BUSY; + else ret = (*xmit)(pkt_dev->skb, odev); - switch (ret) { - case NETDEV_TX_OK: - txq_trans_update(txq); - pkt_dev->last_ok = 1; - pkt_dev->sofar++; - pkt_dev->seq_num++; - pkt_dev->tx_bytes += pkt_dev->cur_pkt_size; - break; - case NETDEV_TX_LOCKED: - cpu_relax(); - goto retry_now; - default: /* Drivers are not supposed to return other values! */ - if (net_ratelimit()) - pr_info("pktgen: %s xmit error: %d\n", - odev->name, ret); - pkt_dev->errors++; - /* fallthru */ - case NETDEV_TX_BUSY: - /* Retry it next time */ - atomic_dec(&(pkt_dev->skb->users)); - pkt_dev->last_ok = 0; - } - - if (pkt_dev->delay) - pkt_dev->next_tx = ktime_add_ns(ktime_now(), - pkt_dev->delay); + + switch (ret) { + case NETDEV_TX_OK: + txq_trans_update(txq); + pkt_dev->last_ok = 1; + pkt_dev->sofar++; + pkt_dev->seq_num++; + pkt_dev->tx_bytes += pkt_dev->cur_pkt_size; + break; + default: /* Drivers are not supposed to return other values! */ + if (net_ratelimit()) + pr_info("pktgen: %s xmit error: %d\n", + odev->name, ret); + pkt_dev->errors++; + /* fallthru */ + case NETDEV_TX_LOCKED: + case NETDEV_TX_BUSY: + /* Retry it next time */ + atomic_dec(&(pkt_dev->skb->users)); + pkt_dev->last_ok = 0; } __netif_tx_unlock_bh(txq); /* If pkt_dev->count is zero, then run forever */ if ((pkt_dev->count != 0) && (pkt_dev->sofar >= pkt_dev->count)) { - while (atomic_read(&(pkt_dev->skb->users)) != 1) { - if (signal_pending(current)) - break; - idle(pkt_dev); - } + pktgen_wait_for_skb(pkt_dev); /* Done with this */ pktgen_stop_device(pkt_dev); @@ -3514,20 +3503,24 @@ static int pktgen_thread_worker(void *arg) while (!kthread_should_stop()) { pkt_dev = next_to_run(t); - if (!pkt_dev && - (t->control & (T_STOP | T_RUN | T_REMDEVALL | T_REMDEV)) - == 0) { - prepare_to_wait(&(t->queue), &wait, - TASK_INTERRUPTIBLE); - schedule_timeout(HZ / 10); - finish_wait(&(t->queue), &wait); + if (unlikely(!pkt_dev && t->control == 0)) { + wait_event_interruptible_timeout(t->queue, + t->control != 0, + HZ/10); + continue; } __set_current_state(TASK_RUNNING); - if (pkt_dev) + if (likely(pkt_dev)) { pktgen_xmit(pkt_dev); + if (need_resched()) + pktgen_resched(pkt_dev); + else + cpu_relax(); + } + if (t->control & T_STOP) { pktgen_stop(t); t->control &= ~(T_STOP); -- 2.25.1