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

[KY Srinivasan]

> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@xxxxxxxxxx]
> Sent: Friday, June 10, 2016 2:47 AM
> To: devel@xxxxxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx; KY Srinivasan <kys@xxxxxxxxxxxxx>; Haiyang
> Zhang <haiyangz@xxxxxxxxxxxxx>
> 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.

Thank you Vitaly. We will further test it.

K. Y
> 
> 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