Re: [dpdk-stable] [PATCH v2] net/ixgbevf: add an option pflink_fullchk to get link status nowait

["Zhang, Qi Z" <qi.z.zhang@intel.com>]

> -----Original Message-----
> From: Zhang, Qi Z
> Sent: Monday, June 10, 2019 7:17 PM
> To: Wang, Haiyue <haiyue.wang@intel.com>; dev@dpdk.org; Lu, Wenzhuo
> <wenzhuo.lu@intel.com>; Wang, Liang-min <liang-min.wang@intel.com>;
> daniels@research.att.com; ktraynor@redhat.com
> Cc: stable@dpdk.org
> Subject: RE: [PATCH v2] net/ixgbevf: add an option pflink_fullchk to get link
> status nowait
> 
> 
> 
> > -----Original Message-----
> > From: Wang, Haiyue
> > Sent: Friday, June 7, 2019 11:56 PM
> > To: dev@dpdk.org; Zhang, Qi Z <qi.z.zhang@intel.com>; Lu, Wenzhuo
> > <wenzhuo.lu@intel.com>; Wang, Liang-min <liang-min.wang@intel.com>;
> > daniels@research.att.com; ktraynor@redhat.com
> > Cc: Wang, Haiyue <haiyue.wang@intel.com>; stable@dpdk.org
> > Subject: [PATCH v2] net/ixgbevf: add an option pflink_fullchk to get
> > link status nowait
> >
> > To get the VF's link status by calling 'rte_eth_link_get_nowait()',
> > the VF not only check PF's physical link status, but also check the mailbox
> running status.
> > And mailbox checking will generate mailbox interrupt in PF, it will be
> > worse if many VFs are running in the system, the PF will have to
> > handle many interrrupts.


interrupts

> >
> > Normally, checking the PF's physical link status is enough for nowait.
> > For different scenarios, adding an 'pflink_fullchk' option to control
> > whether to check the link fully or not.
> 
> Seems the patch change the default behavior which is always "fully check", I
> assume a no fully check does not guarantee the link status is synced correctly,
> right?
> should we implement this devargs in an inverse way to avoid the inconsistent
> with previous version?
> From my view correctness should take high priority than performance.

Checked with author, actually below patch change the default behavior on nowait case
Fixes: 91546fb62e67 ("net/ixgbevf: fix link state")
The patch roll it back and add devarg option for specific requirement, that make sense.

Applied to dpdk-next-net-intel.

Thanks
Qi