Re: [PATCH] vhost: remove lockless enqueue to the virtio ring

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

On Wed, Mar 16, 2016 at 08:20:37AM +0000, Xie, Huawei wrote:
> On 3/15/2016 7:14 AM, Thomas Monjalon wrote:
> > 2016-01-05 07:16, Xie, Huawei:
> >> On 1/5/2016 2:42 PM, Xie, Huawei wrote:
> >>> This patch removes the internal lockless enqueue implmentation.
> >>> DPDK doesn't support receiving/transmitting packets from/to the same
> >>> queue. Vhost PMD wraps vhost device as normal DPDK port. DPDK
> >>> applications normally have their own lock implmentation when enqueue
> >>> packets to the same queue of a port.
> >>>
> >>> The atomic cmpset is a costly operation. This patch should help
> >>> performance a bit.
> >>>
> >>> Signed-off-by: Huawei Xie <huawei.xie@intel.com>
> >> This patch modifies the API's behavior, which is also a trivial ABI
> >> change. In my opinion, application shouldn't rely on previous behavior.
> >> Anyway, i am checking how to declare the ABI change.
> > I guess this patch is now obsolete?
> 
> How about we delay this to next release after more considerations,

I'd suggest so.

> whether we should keep this behavior, and what is the best way for
> concurrency in vhost.

I'm wondering should we do an announcement first, to notify user the
behaviour change?

	--yliu