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  1. 11 6月, 2013 11 次提交
    • C
      net: remove last caller of skb_tail_offset() and itself · 30f3a40f
      由 Cong Wang 提交于 
      Similar to the following commits:

commit 00f97da1 (netpoll: fix position of network header)
commit 525cebed (pktgen: Fix position of ip and udp header)

using skb_tail_offset() seems not correct since the offset
is based on head pointer.

With the last caller removed, skb_tail_offset() can be killed
finally.

Cc: Thomas Graf <tgraf@suug.ch>
Cc: Daniel Borkmann <dborkmann@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: NCong Wang <amwang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      30f3a40f
    • D
      Merge branch 'll_poll' · 0a4db187
      由 David S. Miller 提交于 
      Eliezer Tamir says:

====================
This patch set adds the ability for the socket layer code to
poll directly on an Ethernet device's RX queue.
This eliminates the cost of the interrupt and context switch
and with proper tuning allows us to get very close to the HW latency.

This is a follow up to Jesse Brandeburg's Kernel Plumbers talk from
last year
http://www.linuxplumbersconf.org/2012/wp-content/uploads/2012/09/2012-lpc-Low-Latency-Sockets-slides-brandeburg.pdf

Patch 1 adds a napi_id and a hashing mechanism to lookup a napi by id.
Patch 2 adds an ndo_ll_poll method and the code that supports it.
Patch 3 adds support for busy-polling on UDP sockets.
Patch 4 adds support for TCP.
Patch 5 adds the ixgbe driver code implementing ndo_ll_poll.
Patch 6 adds additional statistics to the ixgbe driver for ndo_ll_poll.

Performance numbers:
     setup                         TCP_RR           UDP_RR
kernel  Config     C3/6 rx-usecs tps cpu% S.dem  tps cpu% S.dem
patched optimized  on   100      87k 3.13 11.4   94K 3.17 10.7
patched optimized  on   0        71k 3.12 14.0   84k 3.19 12.0
patched optimized  on   adaptive 80k 3.13 12.5   90k 3.46 12.2
patched typical    on   100      72  3.13 14.0   79k 3.17 12.8
patched typical    on   0        60k 2.13 16.5   71k 3.18 14.0
patched typical    on   adaptive 67k 3.51 16.7   75k 3.36 14.5
3.9     optimized  on   adaptive 25k 1.0  12.7   28k 0.98 11.2
3.9     typical    off  0        48k 1.09  7.3   52k 1.11 4.18
3.9     typical    0ff  adaptive 35k 1.12 4.08   38k 0.65 5.49
3.9     optimized  off  adaptive 40k 0.82 4.83   43k 0.70 5.23
3.9     optimized  off  0        57k 1.17 4.08   62k 1.04 3.95

Test setup details:
Machines: each with two Intel Xeon 2680 CPUs and X520 (82599) optical
NICs
Tests: Netperf tcp_rr and udp_rr, 1 byte (round trips per second)
Kernel: unmodified 3.9 and patched 3.9
Config: typical is derived from RH6.2, optimized is a stripped down
config.
Interrupt coalescing (ethtool rx-usecs) settings: 0=off, 1=adaptive,
100 us
When C3/6 states were turned on (via BIOS) the performance governor
was used.

These performance numbers were measured with v2 of the patch set.
Performance of the optimized config with an rx-usecs setting of 100
(the first line in the table above) was tracked during the evolution
of the patches and has never varied by more than 1%.

Design:
A global hash table that allows us to look up a struct napi by a
unique id was added.

A napi_id field was added both to struct sk_buff and struct sk.
This is used to track which NAPI we need to poll for a specific
socket.

The device driver marks every incoming skb with this id.
This is propagated to the sk when the socket is looked up in the
protocol handler.

When the socket code does not find any more data on the socket queue,
it now may call ndo_ll_poll which will crank the device's rx queue and
feed incoming packets to the stack directly from the context of the
socket.

A sysctl value (net.core4.low_latency_poll) controls how many
microseconds we busy-wait before giving up. (setting to 0 globally
disables busy-polling)

Locking:

1. Locking between napi poll and ndo_ll_poll:
Since what needs to be locked between a device's NAPI poll and
ndo_ll_poll, is highly device / configuration dependent, we do this
inside the Ethernet driver.
For example, when packets for high priority connections are sent to
separate rx queues, you might not need locking between napi poll and
ndo_ll_poll at all.

For ixgbe we only lock the RX queue.
ndo_ll_poll does not touch the interrupt state or the TX queues.
(earlier versions of this patchset did touch them,
but this design is simpler and works better.)

If a queue is actively polled by a socket (on another CPU) napi poll
will not service it, but will wait until the queue can be locked
and cleaned before doing a napi_complete().
If a socket can't lock the queue because another CPU has it,
either from napi or from another socket polling on the queue,
the socket code can busy wait on the socket's skb queue.

Ndo_ll_poll does not have preferential treatment for the data from the
calling socket vs. data from others, so if another CPU is polling,
you will see your data on this socket's queue when it arrives.

Ndo_ll_poll is called with local BHs disabled, so it won't race on
the same CPU with net_rx_action, which calls the napi poll method.

2. Napi_hash
The napi hash mechanism uses RCU.
napi_by_id() must be called under rcu_read_lock().
After a call to napi_hash_del(), caller must take care to wait an rcu
grace period before freeing the memory containing the napi struct.
(Ixgbe already had this because the queue vector structure uses rcu to
protect the statistics counters in it.)

how to test:

1. The patchset should apply cleanly to net-next.
(don't forget to configure INET_LL_RX_POLL).

2. The ethtool -c setting for rx-usecs should be on the order of 100.

3. Use ethtool -K to disable GRO and LRO
(You are encouraged to try it both ways. If you find that your
workload
does better with GRO on do tell us.)

4. Sysctl value net.core.low_latency_poll controls how long
(in us) to busy-wait for more data, You are encouraged to play
with this and see what works for you. The default is now 0 so you need
to
set it to turn the feature on. I recommend a value around 50.

4. benchmark thread and IRQ should be bound to separate cores.
Both cores should be on the same CPU NUMA node as the NIC.
When the app and the IRQ run on the same CPU  you get a small penalty.
If interrupt coalescing is set to a low value this penalty can be very
large.

5. If you suspect that your machine is not configured properly,
use numademo to make sure that the CPU to memory BW is OK.
numademo 128m memcpy local copy numbers should be more than
8GB/s on a properly configured machine.

Change log:
v10
- removed select/poll support. (we will work on this some more and try again)
v9
- correct sysctl proc_handler, reported by Eric Dumazet and Amir Vadai.
- more int -> bool changes, reported by Eric Dumazet.
- better mask testing in sock_poll(), reported by Eric Dumazet.

v8
- split out udp and select/poll into separate patches.
  what used to be patch 2/5 is now three patches.
- type corrections from Amir Vadai and Cong Wang:
  one unsigned long that was left when changing to cycles_t
  int -> bool
- more detailed patch descriptions.

v7
- suggested by Ben Hutchings and Eric Dumazet:
  type fixes, static for globals in net/core.c,
  avoid napi_id collisions in napi_hash_add()

v6
- many small fixes suggested by Eric Dumazet:
  data locality, typos, documentation
  protect napi_hash insert/delete with a spinlock (napi_gen_id is no
  longer atomic_t since it's only accessed with the spinlock held.)
- added IPv6 TCP and UDP support (only minimally tested)

v5
- corrections suggested by Ben Hutchings:
  fixed typos, moved the config option and sysctl value from IPv4 to net
- moved sk_mark_ll() to the protocol handlers
- removed global id mechanism, replaced with a hashed napi_id.
  based on code sample from Eric Dumazet
  Note that ixgbe_free_q_vector() already waits an rcu grace period
  before freeing the q_vector, so nothing additional needs to be done
  when adding a call to napi_hash_del().
- simple poll/select support

v4
- removed separate config option for TCP as suggested Eric Dumazet.
- added linux mib counter for packets received through the low latency path,
  as suggested by Andi Kleen.
- re-allow module unloading, remove module param, use a global generation id
  instead to prevent the use of a stale napi pointer, as suggested
  by Eric Dumazet
- updated Documentation/networking/ip-sysctl.txt text

v3
- coding style changes suggested by Dave Miller

v2
- the sysctl knob is now in microseconds. The default value is now 0 (off).
- for now the code depends at configure time on CONFIG_I86_TSC
- the napi reference in struct skb is now a union with the dma cookie
  since the former is only used on RX and the latter on TX,
  as suggested by Eric Dumazet.
- we do a better job at honoring non-blocking operations.
- removed busy-polling support for tcp_read_sock()
- remove dynamic disabling of GRO
- coding style fixes
- disallow unloading the device module after the feature has been used

Credit:
Jesse Brandeburg, Arun Chekhov Ilango, Julie Cummings,
Alexander Duyck, Eric Geisler, Jason Neighbors, Yadong Li,
Mike Polehn, Anil Vasudevan, Don Wood
Special thanks for finding bugs in earlier versions:
Willem de Bruijn and Andi Kleen
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      0a4db187
    • E
      ixgbe: add extra stats for ndo_ll_poll · 7e15b90f
      由 Eliezer Tamir 提交于 
      Add additional statistics to the ixgbe driver for ndo_ll_poll
Defined under LL_EXTENDED_STATS
Signed-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: NJesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      7e15b90f
    • E
      ixgbe: add support for ndo_ll_poll · 5a85e737
      由 Eliezer Tamir 提交于 
      Add the ixgbe driver code implementing ndo_ll_poll.
Adds ndo_ll_poll method and locking between it and the napi poll.
When receiving a packet we use skb_mark_ll to record the napi it came from.
Add each napi to the napi_hash right after netif_napi_add().
Signed-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: NJesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      5a85e737
    • E
      tcp: add low latency socket poll support. · d30e383b
      由 Eliezer Tamir 提交于 
      Adds low latency socket poll support for TCP.
In tcp_v[46]_rcv() add a call to sk_mark_ll() to copy the napi_id
from the skb to the sk.
In tcp_recvmsg(), when there is no data in the socket we busy-poll.
This is a good example of how to add busy-poll support to more protocols.
Signed-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: NJesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Tested-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      d30e383b
    • E
      udp: add low latency socket poll support · a5b50476
      由 Eliezer Tamir 提交于 
      Add upport for busy-polling on UDP sockets.
In __udp[46]_lib_rcv add a call to sk_mark_ll() to copy the napi_id
from the skb into the sk.
This is done at the earliest possible moment, right after we identify
which socket this skb is for.
In __skb_recv_datagram When there is no data and the user
tries to read we busy poll.
Signed-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: NJesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Tested-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      a5b50476
    • E
      net: add low latency socket poll · 06021292
      由 Eliezer Tamir 提交于 
      Adds an ndo_ll_poll method and the code that supports it.
This method can be used by low latency applications to busy-poll
Ethernet device queues directly from the socket code.
sysctl_net_ll_poll controls how many microseconds to poll.
Default is zero (disabled).
Individual protocol support will be added by subsequent patches.
Signed-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: NJesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Tested-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      06021292
    • E
      net: add napi_id and hash · af12fa6e
      由 Eliezer Tamir 提交于 
      Adds a napi_id and a hashing mechanism to lookup a napi by id.
This will be used by subsequent patches to implement low latency
Ethernet device polling.
Based on a code sample by Eric Dumazet.
Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Tested-by: NWillem de Bruijn <willemb@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      af12fa6e
    • M
      bcm63xx_enet: add support for Broadcom BCM63xx integrated gigabit switch · 6f00a022
      由 Maxime Bizon 提交于 
      Newer Broadcom BCM63xx SoCs: 6328, 6362 and 6368 have an integrated switch
which needs to be driven slightly differently from the traditional
external switches. This patch introduces changes in arch/mips/bcm63xx in order
to:

- register a bcm63xx_enetsw driver instead of bcm63xx_enet driver
- update DMA channels configuration & state RAM base addresses
- add a new platform data configuration knob to define the number of
  ports per switch/device and force link on some ports
- define the required switch registers

On the driver side, the following changes are required:

- the switch ports need to be polled to ensure the link is up and
  running and RX/TX can properly work
- basic switch configuration needs to be performed for the switch to
  forward packets to the CPU
- update the MIB counters since the integrated
Signed-off-by: NMaxime Bizon <mbizon@freebox.fr>
Signed-off-by: NJonas Gorski <jogo@openwrt.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      6f00a022
    • M
      bcm63xx_enet: split DMA channel register accesses · 0ae99b5f
      由 Maxime Bizon 提交于 
      The current bcm63xx_enet driver always uses bcmenet_shared_base whenever
it needs to access DMA channel configuration space or access the DMA
channel state RAM. Split these register in 3 parts to be more accurate:

- global DMA configuration
- per DMA channel configuration space
- per DMA channel state RAM space

This is preliminary to support new chips where the global DMA
configuration remains the same, but there is a varying number of DMA
channels located at a different memory offset.
Signed-off-by: NMaxime Bizon <mbizon@freebox.fr>
Signed-off-by: NJonas Gorski <jogo@openwrt.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      0ae99b5f
    • M
      bcm63xx_enet: implement reset autoneg ethtool callback · 7260aac9
      由 Maxime Bizon 提交于 
      Implement the rset_nway ethtool callback which uses libphy generic
autonegotiation restart function.
Signed-off-by: NMaxime Bizon <mbizon@freebox.fr>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      7260aac9
  3. 08 6月, 2013 27 次提交
  5. 07 6月, 2013 2 次提交