svn commit: r323516 - in head/sys: dev/bnxt dev/e1000 kern net sys

Wed Sep 13 07:11:56 UTC 2017

In message <4D5AE475-5A38-4429-8B71-DBECDFB0A1FF at gmail.com>, Ngie Cooper 
writes
:
> 
> > On Sep 12, 2017, at 18:18, Stephen Hurd <shurd at FreeBSD.org> wrote:
> > 
> > Author: shurd
> > Date: Wed Sep 13 01:18:42 2017
> > New Revision: 323516
> > URL: https://svnweb.freebsd.org/changeset/base/323516
> > 
> > Log:
> >  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
> 
> *gasps at the LoC count and number of changed drivers*
> 
> Could someone please better break this up in the future..?

Agreed. Down the road parsing out individual commits in this jumbo commit 
will be difficult to parse. IMO this may as well have simply been, import 
from https://github.com/mattmacy/networking/, just like Mr. Torvalds does 
at kernel.org. I expect to see a commit like this there but not here. Can 
we break this down to its functional commits?

-- 
Cheers,
Cy Schubert <Cy.Schubert at cschubert.com>
FreeBSD UNIX:  <cy at FreeBSD.org>   Web:  http://www.FreeBSD.org

	The need of the many outweighs the greed of the few.