Chelsio's TCP offload engine supports direct DMA of received TCP payload
into wired user buffers. This feature is known as Direct-Data Placement.
However, to scale well the adapter needs to prepare buffers for DDP
before data arrives. aio_read() is more amenable to this requirement than
read() as applications often call read() only after data is available in
the socket buffer.
When DDP is enabled, TOE sockets use the recently added pru_aio_queue
protocol hook to claim aio_read(2) requests instead of letting them use
the default AIO socket logic. The DDP feature supports scheduling DMA
to two buffers at a time so that the second buffer is ready for use
after the first buffer is filled. The aio/DDP code optimizes the case
of an application ping-ponging between two buffers (similar to the
zero-copy bpf(4) code) by keeping the two most recently used AIO buffers
wired. If a buffer is reused, the aio/DDP code is able to reuse the
vm_page_t array as well as page pod mappings (a kind of MMU mapping the
Chelsio NIC uses to describe user buffers). The generation of the
vmspace of the calling process is used in conjunction with the user
buffer's address and length to determine if a user buffer matches a
previously used buffer. If an application queues a buffer for AIO that
does not match a previously used buffer then the least recently used
buffer is unwired before the new buffer is wired. This ensures that no
more than two user buffers per socket are ever wired.
Note that this feature is best suited to applications sending a steady
stream of data vs short bursts of traffic.
Discussed with: np
Relnotes: yes
Sponsored by: Chelsio Communications
This provides a constant ABI and layout for these structures (especially
struct adapter) avoiding some foot shooting.
Discussed with: np
Sponsored by: Chelsio Communications
Drivers (ULDs) and the base if_cxgbe driver.
Track the per-adapter activation of ULDs in a new "active_ulds" field.
This was done pretty arbitrarily before this change -- via TOM_INIT_DONE
in adapter->flags for TOM, and the (1 << MAX_NPORTS) bit in
adapter->offload_map for iWARP.
iWARP and hw-accelerated iSCSI rely on the TOE (supported by the TOM
ULD). The rules are:
a) If the iWARP and/or iSCSI ULDs are available when TOE is enabled then
iWARP and/or iSCSI are enabled too.
b) When the iWARP and iSCSI modules are loaded they go looking for
adapters with TOE enabled and enable themselves on that adapter.
c) You cannot deactivate or unload the TOM module from underneath iWARP
or iSCSI. Any such attempt will fail with EBUSY.
MFC after: 2 weeks
(I'm committing this on behalf of my colleagues in the Storage team
at Chelsio).
Submitted by: Sreenivasa Honnur <shonnur at chelsio dot com>
Sponsored by: Chelsio Communications.
them up as part of firmware initialization (which the driver gets to do
only if it's the master driver).
Read the range of tids available for the ETHOFLD functionality if it's
enabled.
New is_ftid() and is_etid() functions to test whether a tid falls within
the range of filter tids or ETHOFLD tids respectively.
MFC after: 2 weeks
when the interface is up.
- Add a tunable to control the TOE's rx coalesce feature (enabled by
default as it always has been). Consider the interface MTU or the
coalesce size when deciding which cluster zone to use to fill the
offload rx queue's free list. The tunable is:
dev.{t4nex,t5nex}.<N>.toe.rx_coalesce
MFC after: 1 day
- Add full support for IPv6 addresses.
- Read the size of the L2 table during attach. Do not assume that PCIe
physical function 4 of the card has all of the table to itself.
- Use FNV instead of Jenkins to hash L3 addresses and drop the private
copy of jhash.h from the driver.
MFC after: 1 week
on the fast data path) and use them instead of frobbing the adapter lock
and busy flag directly.
Other changes made while reworking all slow operations:
- Wait for the reply to a filter request (add/delete). This guarantees
that the operation is complete by the time the ioctl returns.
- Tidy up the tid_info structure.
- Do not allow the tx queue size to be set to something that's not a
power of 2.
MFC after: 1 week
Basically, this is automatic rx zero copy when feasible. TCP payload is
DMA'd directly into the userspace buffer described by the uio submitted
in soreceive by an application.
- Works with sockets that are being handled by the TCP offload engine
of a T4 chip (you need t4_tom.ko module loaded after cxgbe, and an
"ifconfig +toe" on the cxgbe interface).
- Does not require any modification to the application.
- Not enabled by default. Use hw.t4nex.<X>.toe.ddp="1" to enable it.
- Stateful TCP offload drivers for Terminator 3 and 4 (T3 and T4) ASICs.
These are available as t3_tom and t4_tom modules that augment cxgb(4)
and cxgbe(4) respectively. The cxgb/cxgbe drivers continue to work as
usual with or without these extra features.
- iWARP driver for Terminator 3 ASIC (kernel verbs). T4 iWARP in the
works and will follow soon.
Build-tested with make universe.
30s overview
============
What interfaces support TCP offload? Look for TOE4 and/or TOE6 in the
capabilities of an interface:
# ifconfig -m | grep TOE
Enable/disable TCP offload on an interface (just like any other ifnet
capability):
# ifconfig cxgbe0 toe
# ifconfig cxgbe0 -toe
Which connections are offloaded? Look for toe4 and/or toe6 in the
output of netstat and sockstat:
# netstat -np tcp | grep toe
# sockstat -46c | grep toe
Reviewed by: bz, gnn
Sponsored by: Chelsio communications.
MFC after: ~3 months (after 9.1, and after ensuring MFC is feasible)
- Device configuration via plain text config file. Also able to operate
when not attached to the chip as the master driver.
- Generic "work request" queue that serves as the base for both ctrl and
ofld tx queues.
- Generic interrupt handler routine that can process any event on any
kind of ingress queue (via a dispatch table).
- A couple of new driver ioctls. cxgbetool can now install a firmware
to the card ("loadfw" command) and can read the card's memory
("memdump" and "tcb" commands).
- Lots of assorted information within dev.t4nex.X.misc.* This is
primarily for debugging and won't show up in sysctl -a.
- Code to manage the L2 tables on the chip.
- Updates to cxgbe(4) man page to go with the tunables that have changed.
- Updates to the shared code in common/
- Updates to the driver-firmware interface (now at fw 1.4.16.0)
MFC after: 1 month
filters working. (All other filters - switch without L2 info rewrite,
steer, and drop - were already fully-functional).
Some contrived examples of "switch" filters with L2 rewriting:
# cxgbetool t4nex0 iport 0 dport 80 action switch vlan +9 eport 3
Intercept all packets received on physical port 0 with TCP port 80 as
destination, insert a vlan tag with VID 9, and send them out of port 3.
# cxgbetool t4nex0 sip 192.168.1.1/32 ivlan 5 action switch \
vlan =9 smac aa:bb:cc:dd:ee:ff eport 0
Intercept all packets (received on any port) with source IP address
192.168.1.1 and VLAN id 5, rewrite the VLAN id to 9, rewrite source mac
to aa:bb:cc:dd:ee:ff, and send it out of port 0.
MFC after: 1 week
- Enable 5-tuple and every-packet lookup.
- Setup the default filter mode to allow filtering/steering based on IP
protocol, ingress port, inner VLAN ID, IP frag, FCoE, and MPS match
type; all combined together. You can also filter based on MAC index,
Ethernet type, IP TOS/IPv6 Traffic Class, and outer VLAN ID but you'll
have to modify the default filter mode and exclude some of the
match-fields in it.
IPv4 and IPv6 SIP/DIP/SPORT/DPORT are always available in all filter
rules.
- Add driver ioctls to get/set the global filter mode.
- Add driver ioctls to program and delete hardware filters. A couple of
the "switch" actions that rewrite Ethernet and VLAN information and
switch the packet out of another port may not work as the L2 code is not
yet in place. Everything else, including all "drop" and "pass" rules
with RSS or absolute qid, should work.
Obtained from: Chelsio Communications
