[dpdk-dev] [PATCH] ethdev: support double precision RED queue weight

[Stephen Hemminger]

On Mon, 10 Dec 2018 05:43:37 +0000
"Rao, Nikhil" <nikhil.rao at intel.com> wrote:

> > -----Original Message-----
> > From: Stephen Hemminger [mailto:stephen at networkplumber.org]
> > Sent: Thursday, November 29, 2018 11:43 AM
> > To: Rao, Nikhil <nikhil.rao at intel.com>
> > Cc: Dumitrescu, Cristian <cristian.dumitrescu at intel.com>; Singh, Jasvinder
> > <jasvinder.singh at intel.com>; dev at dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH] ethdev: support double precision RED queue
> > weight
> > 
> > On Thu, 29 Nov 2018 11:24:42 +0530
> > Nikhil Rao <nikhil.rao at intel.com> wrote:
> >   
> > > RED queue weight is currently specified as a negated log of 2.
> > >
> > > Add support for RED queue weight to be specified in double precision
> > > and TM capability flags for double precision and negated log2 RED
> > > queue weight support.
> > >
> > > Signed-off-by: Nikhil Rao <nikhil.rao at intel.com>  
> > 
> > Since this is an ABI break anyway, why not just commit to the new format?  
> 
> Hi Stephen,
> 
> Can you please provide more detail on your comment ?  are you suggesting replacing the wq_log2/wq_dp with a double ?
> 
> Thanks,
> Nikhil


My comment is that since you are changing a structure layout, which would
break existing users; why not go farther and just fix the API to a better
version. I don't think any projects use this code anyway,
see my talk (https://github.com/shemminger/dpdk-metrics).

Isn't floating point going to be expensive. Or is it only during the setup
process, not enqueue/dequeue.