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author | Julian Wiedmann <jwi@linux.ibm.com> | 2019-04-17 18:17:35 +0200 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2019-04-17 10:33:59 -0700 |
commit | 54a50941b7db8726732919daa859b931a9f496e2 (patch) | |
tree | 8d34ae098a862a52ff80102c5344d959e2998c79 /drivers/s390/net/qeth_l3_main.c | |
parent | s390/qeth: simplify QoS code (diff) | |
download | linux-dev-54a50941b7db8726732919daa859b931a9f496e2.tar.xz linux-dev-54a50941b7db8726732919daa859b931a9f496e2.zip |
s390/qeth: stop/wake TX queues based on their fill level
Current xmit code only stops the txq after attempting to fill an
IO buffer that hasn't been TX-completed yet. In many-connection
scenarios, this can result in frequent rejected TX attempts, requeuing
of skbs with NETDEV_TX_BUSY and extra overhead.
Now that we have a proper 1-to-1 relation between stack-side txqs and
our HW Queues, overhaul the stop/wake logic so that the xmit code
stops the txq as needed.
Given that we might map multiple skbs into a single buffer, it's crucial
to ensure that the queue always provides an _entirely_ empty IO buffer.
Otherwise large skbs (eg TSO) might not fit into the last available
buffer. So whenever qeth_do_send_packet() first utilizes an _empty_
buffer, it updates & checks the used_buffers count.
This now ensures that an skb passed to qeth_xmit() can always be mapped
into an IO buffer, so remove all of the -EBUSY roll-back handling in the
TX path. We preserve the minimal safety-checks ("Is this IO buffer
really available?"), just in case some nasty future bug ever attempts to
corrupt an in-use buffer.
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
-rw-r--r-- | drivers/s390/net/qeth_l3_main.c | 18 |
1 files changed, 2 insertions, 16 deletions
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c index 65244da4f415..4c9394105138 100644 --- a/drivers/s390/net/qeth_l3_main.c +++ b/drivers/s390/net/qeth_l3_main.c @@ -2036,7 +2036,6 @@ static void qeth_l3_fixup_headers(struct sk_buff *skb) static int qeth_l3_xmit(struct qeth_card *card, struct sk_buff *skb, struct qeth_qdio_out_q *queue, int ipv, int cast_type) { - unsigned char eth_hdr[ETH_HLEN]; unsigned int hw_hdr_len; int rc; @@ -2046,17 +2045,10 @@ static int qeth_l3_xmit(struct qeth_card *card, struct sk_buff *skb, rc = skb_cow_head(skb, hw_hdr_len - ETH_HLEN); if (rc) return rc; - skb_copy_from_linear_data(skb, eth_hdr, ETH_HLEN); skb_pull(skb, ETH_HLEN); qeth_l3_fixup_headers(skb); - rc = qeth_xmit(card, skb, queue, ipv, cast_type, qeth_l3_fill_header); - if (rc == -EBUSY) { - /* roll back to ETH header */ - skb_push(skb, ETH_HLEN); - skb_copy_to_linear_data(skb, eth_hdr, ETH_HLEN); - } - return rc; + return qeth_xmit(card, skb, queue, ipv, cast_type, qeth_l3_fill_header); } static netdev_tx_t qeth_l3_hard_start_xmit(struct sk_buff *skb, @@ -2091,8 +2083,6 @@ static netdev_tx_t qeth_l3_hard_start_xmit(struct sk_buff *skb, if (cast_type == RTN_BROADCAST && !card->info.broadcast_capable) goto tx_drop; - netif_stop_subqueue(dev, txq); - if (ipv == 4 || IS_IQD(card)) rc = qeth_l3_xmit(card, skb, queue, ipv, cast_type); else @@ -2102,16 +2092,12 @@ static netdev_tx_t qeth_l3_hard_start_xmit(struct sk_buff *skb, if (!rc) { QETH_TXQ_STAT_INC(queue, tx_packets); QETH_TXQ_STAT_ADD(queue, tx_bytes, tx_bytes); - netif_wake_subqueue(dev, txq); return NETDEV_TX_OK; - } else if (rc == -EBUSY) { - return NETDEV_TX_BUSY; - } /* else fall through */ + } tx_drop: QETH_TXQ_STAT_INC(queue, tx_dropped); kfree_skb(skb); - netif_wake_subqueue(dev, txq); return NETDEV_TX_OK; } |