Re: [PATCH] Add an API to query enabled core index

[Patrick Lu <patrick.lu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On Thu, Jun 12, 2014 at 08:54:11AM -0700, Richardson, Bruce wrote:
> 
> 
> > -----Original Message-----
> > From: Olivier MATZ [mailto:olivier.matz-pdR9zngts4EAvxtiuMwx3w@public.gmane.org]
> > Sent: Thursday, June 12, 2014 1:20 AM
> > To: Richardson, Bruce; Thomas Monjalon; Lu, Patrick
> > Cc: dev-VfR2kkLFssw@public.gmane.org
> > Subject: Re: [dpdk-dev] [PATCH] Add an API to query enabled core index
> > 
> > Hello,
> > 
> > On 06/11/2014 11:57 PM, Richardson, Bruce wrote:
> > >> I think core_id2 is not a representative name.
> > >> What do you think of renaming core_id as lcore_hwid and core_id2 as
> > >> lcore_index?
> > >>
> > >> --
> > > I like lcore_index as the name for the new function. However, I'm not sure in
> > that case that we want/need to rename the old one.
> > 
> > What about lcore_rank ?
> > It may avoid confusion between "id" and "index", which are quite
> > close visually and phonetically.
> 
> Not sure about rank, index is more correct. How about making it "app_index" or "app_idx", to indicate that it's not a global id but rather the idx that's local to the running app instance.
> 
> Other alternative approach would be rte_lcore_position() API that takes a hardware lcore id, and tells you it's "position" in the coremask for the application, i.e. lcore 6 is in position 2 (of e.g. 5) lcores, for instance. [It would obviously return -1 on non-active cores.]
The main purpose of this API is for a running thread know its relative
index in all enabled core, so it can access the shared data structure
with correct index. I don't know if we necessarily need to pass in a
hardware lcore id, I suggest the API will implicit call rte_lcore_id.

I think either position or index is a much appropriated name for this
API.
> 
> > 
> > I agree that we should not change the old lcore_id, its name is already
> > appropriate.
> > 
> And it's so widely used that changing it would break the code of probably every single Intel DPDK application ever written!