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Filename Latest commit message Latest commit date
Paolo Abeni ba27b4cdaa net: dev: introduce support for sch BYPASS for lockless qdisc
With commit c5ad119fb6 ("net: sched: pfifo_fast use skb_array")
pfifo_fast no longer benefit from the TCQ_F_CAN_BYPASS optimization.
Due to retpolines the cost of the enqueue()/dequeue() pair has become
relevant and we observe measurable regression for the uncontended
scenario when the packet-rate is below line rate.

After commit 46b1c18f9d ("net: sched: put back q.qlen into a
single location") we can check for empty qdisc with a reasonably
fast operation even for nolock qdiscs.

This change extends TCQ_F_CAN_BYPASS support to nolock qdisc.
The new chunk of code mirrors closely the existing one for traditional
qdisc, leveraging a newly introduced helper to read atomically the
qdisc length.

Tested with pktgen in queue xmit mode, with pfifo_fast, a MQ
device, and MQ root qdisc:

threads         vanilla         patched
                kpps            kpps
1               2465            2889
2               4304            5188
4               7898            9589

Same as above, but with a single queue device:

threads         vanilla         patched
                kpps            kpps
1               2556            2827
2               2900            2900
4               5000            5000
8               4700            4700

No mesaurable changes in the contended scenarios, and more 10%
improvement in the uncontended ones.

 v1 -> v2:
  - rebased after flag name change

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Tested-by: Ivan Vecera <ivecera@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-03-23 21:52:36 -04:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2019-03-16 12:20:08 -07:00
block
certs
crypto
Documentation ipv4: Allow amount of dirty memory from fib resizing to be controllable 2019-03-21 13:29:53 -07:00
drivers net: phy: Correct Cygnus/Omega PHY driver prompt 2019-03-23 20:54:18 -04:00
fs
include net: sched: add empty status flag for NOLOCK qdisc 2019-03-23 21:52:36 -04:00
init
ipc
kernel genetlink: make policy common to family 2019-03-22 10:38:23 -04:00
lib rhashtable: rename rht_for_each*continue as *from. 2019-03-21 14:01:10 -07:00
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net net: dev: introduce support for sch BYPASS for lockless qdisc 2019-03-23 21:52:36 -04:00
samples
scripts
security
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tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2019-03-16 12:20:08 -07:00
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.