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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_core.h | |
parent | e6c15b5f34a9c7dede9ba4b251f90abe5fbd40f6 (diff) | |
download | linux-54a50941b7db8726732919daa859b931a9f496e2.tar.gz linux-54a50941b7db8726732919daa859b931a9f496e2.tar.bz2 linux-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 'drivers/s390/net/qeth_core.h')
-rw-r--r-- | drivers/s390/net/qeth_core.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/s390/net/qeth_core.h b/drivers/s390/net/qeth_core.h index 4989dc7b58c1..fbaf434e2e34 100644 --- a/drivers/s390/net/qeth_core.h +++ b/drivers/s390/net/qeth_core.h @@ -481,6 +481,7 @@ struct qeth_out_q_stats { u64 skbs_linearized_fail; u64 tso_bytes; u64 packing_mode_switch; + u64 stopped; /* rtnl_link_stats64 */ u64 tx_packets; @@ -511,6 +512,11 @@ struct qeth_qdio_out_q { atomic_t set_pci_flags_count; }; +static inline bool qeth_out_queue_is_full(struct qeth_qdio_out_q *queue) +{ + return atomic_read(&queue->used_buffers) >= QDIO_MAX_BUFFERS_PER_Q; +} + struct qeth_qdio_info { atomic_t state; /* input */ |