netdev - [RFC net-next PATCH V3 0/2] qdisc bulk dequeuing and utilizing delayed tailptr updates

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Message-ID: <20140919204706.3231.59125.stgit@dragon>
Date:	Fri, 19 Sep 2014 22:49:08 +0200
From:	Jesper Dangaard Brouer <brouer@...hat.com>
To:	Jesper Dangaard Brouer <brouer@...hat.com>, netdev@...r.kernel.org,
	"David S. Miller" <davem@...emloft.net>,
	Tom Herbert <therbert@...gle.com>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	Florian Westphal <fw@...len.de>,
	Daniel Borkmann <dborkman@...hat.com>
Cc:	Jamal Hadi Salim <jhs@...atatu.com>,
	Alexander Duyck <alexander.duyck@...il.com>,
	John Fastabend <john.r.fastabend@...el.com>,
	Dave Taht <dave.taht@...il.com>, toke@...e.dk
Subject: [RFC net-next PATCH V3 0/2] qdisc bulk dequeuing and utilizing
	delayed tailptr updates

This patchset uses DaveM's recent API changes to dev_hard_start_xmit(),
from the qdisc layer, to implement dequeue bulking.

RFC V3: Keeping the ball rolling.

This patchset should now use BQL correctly.  I've done lots of testing
for Head-of-Line blocking issues that can occur due to requeue of a
SKB bulk list.  I've not been able to provoke any HoL blocking
situation, simply because BQL is doing such a good job, thus I'm
unable to "overshoot" HW/BQL limits with more than a single packet.

This patch chooses a very conservative approach, as by default only
allowing dequeue of one extra packet, besides the normal dequeue.

Open questions:

- How do we expose tuning to userspace?
  Patch adds /proc/sys/net/core/qdisc_bulk_dequeue_limit but I don't like it...
  Per device tunable?

- Can/should we limit dequeue bulking to devices supporting BQL?


Based on top of net-next:
 commit cb93471acc (tcp: do not fake tcp headers in tcp_send_rcvq())


---

Jesper Dangaard Brouer (1):
      qdisc: bulk dequeue support for qdiscs with TCQ_F_ONETXQUEUE

Tom Herbert (1):
      net: Functions to report space available in device TX queues


 include/linux/netdevice.h  |   28 ++++++++++++++++--
 include/net/sch_generic.h  |    2 +
 net/core/sysctl_net_core.c |    9 ++++++
 net/sched/sch_generic.c    |   70 ++++++++++++++++++++++++++++++++++++++++++--
 4 files changed, 104 insertions(+), 5 deletions(-)

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