Re: [net-next rfc V3 0/9] Multiqueue API for macvtap

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jun 05, 2013 at 02:36:23PM +0800, Jason Wang wrote:
> Hi all:
> 
> This series implements a v3 of fully tuntap compatiable API which could be used
> by userspace to manage multiple macvtap queues. The main parts is to add
> TUNSETQUEUE ioctl support for macvtap.
> 
> Patch 1 - 5 was some tuntap compatibility and misc cleanups.
> Patch 6 removes the linear search in macvtap by reshuffling the macvtaps array
> each time a queue is removed. After this, we could store both enabled and
> disabled queues in the same array without introducing extra data structure.
> Patch 7 let TUNSETIFF can create multiqueue device, nothing but some check
> were added.
> Patch 8 implement TUNSETQUEUE ioctl
> Patch 9 reports IFF_MULTI_QUEUE to userspace to notify the userspace that the
> multiqueue API is completed.
> 
> Flow caches implememtation were missed in this version, since I am doing
> rework on the tuntap flow caches. Have some some stress test with both netperf
> and pktgen.
> 
> Please review, thanks.

FYI by netdev rules RFC means "don't apply yet".

> Changes from V2:
> - Don't place disabled taps in the array and use a linked like to track all taps
> - Remove unnecessary best-effort barriers
> - Add ACCESS_ONCE() for vlan->numvtaps to prevent compiler generate unexpected
>   codes
> - Add a comment to explain that numvtaps is just a hint in macvtap_get_queue()
> - blank line fixes
> 
> Changes from V1:
> - Drop the patch of "return -EBADFD when TUNGETIFF fails" to preserve backward
>   compatibility
> - Add a small patch of optimizing macvtap_do_read() (see patch 1/8)
> - Use different functions to do tap enabling and creating
> - Use different functions to do tap disabling and closing
> - Remove the emtpy line in patch 6/8
> - Add a line in patch 3/8
> - Add a comment to explain the checking when doing TUNSETIFF with
>   IFF_MULTI_QUEUE
> - Add comments to explian the second swapping when moving taps between disabled
>   areas and enabled areas.
> - Fix the commit log of patch 7/8 ( v1 says the linked list were used which is
>   wrong )
> - Other minor bug fixes
> 
> Jason Wang (9):
>   macvtap: fix a possible race between queue selection and changing
>     queues
>   macvtap: do not add self to waitqueue if doing a nonblock read
>   macvlan: switch to use IS_ENABLED()
>   macvtap: introduce macvtap_get_vlan()
>   macvlan: change the max number of queues to 16
>   macvtap: eliminate linear search
>   macvtap: allow TUNSETIFF to create multiqueue device
>   macvtap: add TUNSETQUEUE ioctl
>   macvtap: enable multiqueue flag
> 
>  drivers/net/macvtap.c      |  261 ++++++++++++++++++++++++++++++++------------
>  include/linux/if_macvlan.h |    8 +-
>  2 files changed, 197 insertions(+), 72 deletions(-)