[dpdk-dev] [PATCH v4 0/6] add Tx preparation
Tomasz Kulasek
tomaszx.kulasek at intel.com
Fri Sep 30 11:00:33 CEST 2016
As discussed in that thread:
http://dpdk.org/ml/archives/dev/2015-September/023603.html
Different NIC models depending on HW offload requested might impose
different requirements on packets to be TX-ed in terms of:
- Max number of fragments per packet allowed
- Max number of fragments per TSO segments
- The way pseudo-header checksum should be pre-calculated
- L3/L4 header fields filling
- etc.
MOTIVATION:
-----------
1) Some work cannot (and didn't should) be done in rte_eth_tx_burst.
However, this work is sometimes required, and now, it's an
application issue.
2) Different hardware may have different requirements for TX offloads,
other subset can be supported and so on.
3) Some parameters (e.g. number of segments in ixgbe driver) may hung
device. These parameters may be vary for different devices.
For example i40e HW allows 8 fragments per packet, but that is after
TSO segmentation. While ixgbe has a 38-fragment pre-TSO limit.
4) Fields in packet may require different initialization (like e.g. will
require pseudo-header checksum precalculation, sometimes in a
different way depending on packet type, and so on). Now application
needs to care about it.
5) Using additional API (rte_eth_tx_prep) before rte_eth_tx_burst let to
prepare packet burst in acceptable form for specific device.
6) Some additional checks may be done in debug mode keeping tx_burst
implementation clean.
PROPOSAL:
---------
To help user to deal with all these varieties we propose to:
1) Introduce rte_eth_tx_prep() function to do necessary preparations of
packet burst to be safely transmitted on device for desired HW
offloads (set/reset checksum field according to the hardware
requirements) and check HW constraints (number of segments per
packet, etc).
While the limitations and requirements may differ for devices, it
requires to extend rte_eth_dev structure with new function pointer
"tx_pkt_prep" which can be implemented in the driver to prepare and
verify packets, in devices specific way, before burst, what should to
prevent application to send malformed packets.
2) Also new fields will be introduced in rte_eth_desc_lim:
nb_seg_max and nb_mtu_seg_max, providing an information about max
segments in TSO and non-TSO packets acceptable by device.
This information is useful for application to not create/limit
malicious packet.
APPLICATION (CASE OF USE):
--------------------------
1) Application should to initialize burst of packets to send, set
required tx offload flags and required fields, like l2_len, l3_len,
l4_len, and tso_segsz
2) Application passes burst to the rte_eth_tx_prep to check conditions
required to send packets through the NIC.
3) The result of rte_eth_tx_prep can be used to send valid packets
and/or restore invalid if function fails.
e.g.
for (i = 0; i < nb_pkts; i++) {
/* initialize or process packet */
bufs[i]->tso_segsz = 800;
bufs[i]->ol_flags = PKT_TX_TCP_SEG | PKT_TX_IPV4
| PKT_TX_IP_CKSUM;
bufs[i]->l2_len = sizeof(struct ether_hdr);
bufs[i]->l3_len = sizeof(struct ipv4_hdr);
bufs[i]->l4_len = sizeof(struct tcp_hdr);
}
/* Prepare burst of TX packets */
nb_prep = rte_eth_tx_prep(port, 0, bufs, nb_pkts);
if (nb_prep < nb_pkts) {
printf("tx_prep failed\n");
/* nb_prep indicates here first invalid packet. rte_eth_tx_prep
* can be used on remaining packets to find another ones.
*/
}
/* Send burst of TX packets */
nb_tx = rte_eth_tx_burst(port, 0, bufs, nb_prep);
/* Free any unsent packets. */
v4 changes:
- tx_prep is now set to default behavior (NULL) for simple/vector path
in fm10k, i40e and ixgbe drivers to increase performance, when
Tx offloads are not intentionally available
v3 changes:
- reworked csum testpmd engine instead adding new one,
- fixed checksum initialization procedure to include also outer
checksum offloads,
- some minor formattings and optimalizations
v2 changes:
- rte_eth_tx_prep() returns number of packets when device doesn't
support tx_prep functionality,
- introduced CONFIG_RTE_ETHDEV_TX_PREP allowing to turn off tx_prep
Tomasz Kulasek (6):
ethdev: add Tx preparation
e1000: add Tx preparation
fm10k: add Tx preparation
i40e: add Tx preparation
ixgbe: add Tx preparation
testpmd: use Tx preparation in csum engine
app/test-pmd/csumonly.c | 97 +++++++++++++++------------
config/common_base | 1 +
drivers/net/e1000/e1000_ethdev.h | 11 ++++
drivers/net/e1000/em_ethdev.c | 5 +-
drivers/net/e1000/em_rxtx.c | 48 +++++++++++++-
drivers/net/e1000/igb_ethdev.c | 4 ++
drivers/net/e1000/igb_rxtx.c | 52 ++++++++++++++-
drivers/net/fm10k/fm10k.h | 6 ++
drivers/net/fm10k/fm10k_ethdev.c | 5 ++
drivers/net/fm10k/fm10k_rxtx.c | 50 +++++++++++++-
drivers/net/i40e/i40e_ethdev.c | 3 +
drivers/net/i40e/i40e_rxtx.c | 72 ++++++++++++++++++++-
drivers/net/i40e/i40e_rxtx.h | 8 +++
drivers/net/ixgbe/ixgbe_ethdev.c | 3 +
drivers/net/ixgbe/ixgbe_ethdev.h | 5 +-
drivers/net/ixgbe/ixgbe_rxtx.c | 56 +++++++++++++++-
drivers/net/ixgbe/ixgbe_rxtx.h | 2 +
lib/librte_ether/rte_ethdev.h | 85 ++++++++++++++++++++++++
lib/librte_mbuf/rte_mbuf.h | 8 +++
lib/librte_net/Makefile | 2 +-
lib/librte_net/rte_pkt.h | 133 ++++++++++++++++++++++++++++++++++++++
21 files changed, 605 insertions(+), 51 deletions(-)
create mode 100644 lib/librte_net/rte_pkt.h
--
1.7.9.5
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