xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Koodi Ongelmat Pull-pyynnöt Actions Paketit Projektit Julkaisut Wiki Toiminta

s390/qeth: stop/wake TX queues based on their fill level

Selaa lähdekoodia 
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>
This commit is contained in:
Julian Wiedmann
2019-04-17 18:17:35 +02:00
committed by David S. Miller
vanhempi e6c15b5f34
commit 54a50941b7
5 muutettua tiedostoa jossa 71 lisäystä ja 48 poistoa
Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/s390/net/qeth_l2_main.c
Näytä tiedosto

@@ -607,11 +607,8 @@ static netdev_tx_t qeth_l2_hard_start_xmit(struct sk_buff *skb,
int rc;
if (IS_IQD(card))
queue = card->qdio.out_qs[qeth_iqd_translate_txq(dev, txq)];
else
queue = card->qdio.out_qs[txq];
netif_stop_subqueue(dev, txq);
txq = qeth_iqd_translate_txq(dev, txq);
queue = card->qdio.out_qs[txq];
if (IS_OSN(card))
rc = qeth_l2_xmit_osn(card, skb, queue);
@@ -622,15 +619,11 @@ static netdev_tx_t qeth_l2_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 */
}
QETH_TXQ_STAT_INC(queue, tx_dropped);
kfree_skb(skb);
netif_wake_subqueue(dev, txq);
return NETDEV_TX_OK;
}