linux-kernel - [PATCH 0/4] Drivers: hv: ring_buffer: make in-place consumption always possible

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Date:	Fri, 10 Jun 2016 11:47:08 +0200
From:	Vitaly Kuznetsov <vkuznets@...hat.com>
To:	devel@...uxdriverproject.org
Cc:	linux-kernel@...r.kernel.org,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Haiyang Zhang <haiyangz@...rosoft.com>
Subject: [PATCH 0/4] Drivers: hv: ring_buffer: make in-place consumption always possible

K. Y.,

I'd like to accompany your netvsc performance improvement work by making
in-place consumption of VMBus packets always possible. Currently we forbid
it when a packet 'wraps around' the ring so we can't provide a single
pointer to it.

The idea if this series is dead simple: let's make a single virtual mapping
for two copies (actually, two sets of pages which consist the ring buffer)
of the ring buffer. With such a mapping we can always provide a pointers
for in-place consumption to drivers. Copy path can also benefit from such
mappings as we eliminate the need for conditional checking in copy_to/
copy_from functions and use a single memcpy().

Lightly tested with 'netvsc: Use the new in-place consumption APIs in the
rx path' patch and with storvsc driver.

Vitaly Kuznetsov (4):
  Drivers: hv: cleanup vmbus_open() for wrap around mappings
  Drivers: hv: ring_buffer: wrap around mappings for ring buffers
  Drivers: hv: ring_buffer: use wrap around mappings in
    hv_copy{from,to}_ringbuffer()
  Drivers: hv: ring_buffer: count on wrap around mappings in
    get_next_pkt_raw()

 drivers/hv/channel.c      | 68 ++++++++++++++++++++++++-----------------------
 drivers/hv/hyperv_vmbus.h |  4 +--
 drivers/hv/ring_buffer.c  | 61 ++++++++++++++++++++++++------------------
 include/linux/hyperv.h    | 32 ++++++++--------------
 4 files changed, 83 insertions(+), 82 deletions(-)

-- 
2.5.5