Commit Graph

9 Commits

Author SHA1 Message Date
Matt Macy
5881181d8c mp_ring: avoid items offset difference between iflib and mp_ring
on architectures without 64-bit atomics

Reported by:	Augustin Cavalier <waddlesplash@gmail.com>
2019-01-03 23:06:05 +00:00
Stephen Hurd
fe51d4cdfe Add knob to control tx ring abdication.
r323954 changed the mp ring behaviour when 64-bit atomics were
available to abdicate the TX ring rather than having one become a
consumer thereby running to completion on TX. The consumer of the mp
ring was then triggered in the tx task rather than blocking the TX call.
While this significantly lowered the number of RX drops in small-packet
forwarding, it also negatively impacts TX performance.

With this change, the default behaviour is reverted, causing one TX ring
to become a consumer during the enqueue call. A new sysctl,
dev.X.Y.iflib.tx_abdicate is added to control this behaviour.

Reviewed by:	gallatin
Sponsored by:	Limelight Networks
Differential Revision:	https://reviews.freebsd.org/D16302
2018-07-20 17:45:26 +00:00
Matt Macy
e335651e1e mp_ring: fix i386
Even though 64-bit atomics are supported on i386 there are panics
indicating that the code does not work correctly there. Switch
to mutex based variant (and fix that while we're here).

Reported by:	pho, kib
2018-05-19 16:44:12 +00:00
Stephen Hurd
1225d9da9f Have ifmp_ring_enqueue() abdicate instead of switch to a consumer
Move TX out of the enqueue() path. As a result, we need
to have ifmp_ring_check_drainage() pick up from the abdicate state.

We also need to either enqueue the TX task, or check drainage
after calling ifmp_ring_enqueue() to ensure it's sent.

This change results in a 30% small packet forwarding improvement.

Reviewed by:	olivier, sbruno
Approved by:	sbruno (mentor)
Sponsored by:	Limelight Networks
Differential Revision:	https://reviews.freebsd.org/D12439
2017-09-23 16:46:30 +00:00
Stephen Hurd
ab2e3f7958 Revert r323516 (iflib rollup)
This was really too big of a commit even if everything worked, but there
are multiple new issues introduced in the one huge commit, so it's not
worth keeping this until it's fixed.

I'll work on splitting this up into logical chunks and introduce them one
at a time over the next week or two.

Approved by:	sbruno (mentor)
Sponsored by:	Limelight Networks
2017-09-16 02:41:38 +00:00
Stephen Hurd
d300df0182 Roll up iflib commits from github. This pulls in most of the work done
by Matt Macy as well as other changes which he has accepted via pull
request to his github repo at https://github.com/mattmacy/networking/

This should bring -CURRENT and the github repo into close enough sync to
allow small feature branches rather than a large chain of interdependant
patches being developed out of tree.  The reset of the synchronization
should be able to be completed on github by splitting the remaining
changes that are not yet ready into short feature branches for later
review as smaller commits.

Here is a summary of changes included in this patch:

1)  More checks when INVARIANTS are enabled for eariler problem
    detection
2)  Group Task Queue cleanups
    - Fix use of duplicate shortdesc for gtaskqueue malloc type.
      Some interfaces such as memguard(9) use the short description to
      identify malloc types, so duplicates should be avoided.
3)  Allow gtaskqueues to use ithreads in addition to taskqueues
    - In some cases, this can improve performance
4)  Better logging when taskqgroup_attach*() fails to set interrupt
    affinity.
5)  Do not start gtaskqueues until they're needed
6)  Have mp_ring enqueue function enter the ABDICATED rather than BUSY
    state.  This moves the TX to the gtaskq and allows processing to
    continue faster as well as make TX batching more likely.
7)  Add an ift_txd_errata function to struct if_txrx.  This allows
    drivers to inspect/modify mbufs before transmission.
8)  Add a new IFLIB_NEED_ZERO_CSUM for drivers to indicate they need
    checksums zeroed for checksum offload to work.  This avoids modifying
    packet data in the TX path when possible.
9)  Use ithreads for iflib I/O instead of taskqueues
10) Clean up ioctl and support async ioctl functions
11) Prefetch two cachlines from each mbuf instead of one up to 128B.  We
    often need to parse packet header info beyond 64B.
12) Fix potential memory corruption due to fence post error in
    bit_nclear() usage.
13) Improved hang detection and handling
14) If the packet is smaller than MTU, disable the TSO flags.
    This avoids extra packet parsing when not needed.
15) Move TCP header parsing inside the IS_TSO?() test.
    This avoids extra packet parsing when not needed.
16) Pass chains of mbufs that are not consumed by lro to if_input()
    rather call if_input() for each mbuf.
17) Re-arrange packet header loads to get as much work as possible done
    before a cache stall.
18) Lock the context when calling IFDI_ATTACH_PRE()/IFDI_ATTACH_POST()/
    IFDI_DETACH();
19) Attempt to distribute RX/TX tasks across cores more sensibly,
    especially when RX and TX share an interrupt.  RX will attempt to
    take the first threads on a core, and TX will attempt to take
    successive threads.
20) Allow iflib_softirq_alloc_generic() to request affinity to the same
    cpus an interrupt has affinity with.  This allows TX queues to
    ensure they are serviced by the socket the device is on.
21) Add new iflib sysctls to net.iflib:
    - timer_int - interval at which to run per-queue timers in ticks
    - force_busdma
22) Add new per-device iflib sysctls to dev.X.Y.iflib
    - rx_budget allows tuning the batch size on the RX path
    - watchdog_events Count of watchdog events seen since load
23) Fix error where netmap_rxq_init() could get called before
    IFDI_INIT()
24) e1000: Fixed version of r323008: post-cold sleep instead of DELAY
    when waiting for firmware
    - After interrupts are enabled, convert all waits to sleeps
    - Eliminates e1000 software/firmware synchronization busy waits after
      startup
25) e1000: Remove special case for budget=1 in em_txrx.c
    - Premature optimization which may actually be incorrect with
      multi-segment packets
26) e1000: Split out TX interrupt rather than share an interrupt for
    RX and TX.
    - Allows better performance by keeping RX and TX paths separate
27) e1000: Separate igb from em code where suitable
    Much easier to understand separate functions and "if (is_igb)" than
    previous tests like "if (reg_icr & (E1000_ICR_RXSEQ | E1000_ICR_LSC))"

#blamebruno

Reviewed by:	sbruno
Approved by:	sbruno (mentor)
Sponsored by:	Limelight Networks
Differential Revision:	https://reviews.freebsd.org/D12235
2017-09-13 01:18:42 +00:00
Pedro F. Giffuni
efc457e1bc sys/net: more spelling. 2016-05-19 16:28:05 +00:00
Scott Long
fc614c29c1 Activate the NO_64BIT_ATOMICS code for mips and powerpc 2016-05-18 15:45:12 +00:00
Scott Long
4c7070db25 Import the 'iflib' API library for network drivers. From the author:
"iflib is a library to eliminate the need for frequently duplicated device
independent logic propagated (poorly) across many network drivers."

Participation is purely optional.  The IFLIB kernel config option is
provided for drivers that want to transition between legacy and iflib
modes of operation.  ixl and ixgbe driver conversions will be committed
shortly.  We hope to see participation from the Broadcom and maybe
Chelsio drivers in the near future.

Submitted by:   mmacy@nextbsd.org
Reviewed by:    gallatin
Differential Revision:  D5211
2016-05-18 04:35:58 +00:00