[dpdk-dev] [PATCH] ethdev: avoid blocking telemetry callback for link status

[Bruce Richardson]

On Tue, Jan 19, 2021 at 10:58:42AM +0800, Min Hu (Connor) wrote:
> Thank Stephen,
> but in which the scenarios, it should wait link to up, in which
> scenarios, it should not ?
> By the way, how to define the "wait" time value ?
> 

I believe the documentation somewhere refers to a wait time of up to 9
seconds, but I don't think it's terribly well defined. Some Intel NICs will
stall for a few seconds if the link is not yet stable or if the link
is down. With the link up, I don't think any NIC fails to return
immediately.
However, if delays in the app are something you want to avoid, the _nowait
varient is the one to call to be sure.

/Bruce

> 
> 
> 在 2021/1/19 10:26, Stephen Hemminger 写道:
> > On Tue, 19 Jan 2021 09:06:48 +0800
> > "Min Hu (Connor)" <humin29 at huawei.com> wrote:
> > 
> > > Hi, Bruce and all,
> > > 	Do you know the difference between "rte_eth_link_get" and
> > > "rte_eth_link_get_nowait"? I know they call funciton "link_update"
> > > with differenct parameter "wait_to_complete"(set 1 means wait, set 0
> > >    means not wait). But how to define the "wait" time, and why it shoud wait?
> > > 	On the further, What are the application scenarios of the two
> > > APIs?
> > > 
> > 
> > The default behavior of rte_eth_link_get (in some drivers) is to wait
> > for link to come up.  Many drivers don't do this. It seems mostly the
> > Intel ones that do.
> > .
> >