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

["Dumitrescu, Cristian" <cristian.dumitrescu@intel.com>]

Maybe we could simplify this discussion by simply creating a new function to return the mask of all enabled cores (as provided through -c coremask EAL option) and have the user utilize this mask to derive whatever info it needs?

Right now, to get the mask of enabled cores, a for loop is required to test each core index one by one and re-create the mask.

In several instances, I needed to know just the number of enabled cores (i.e. number of bits set in -c coremask), and there was no alternative to the for loop above. But given such a function, we can quickly do:
	uint64_t coremask = rte_eal_coremask();
	n_lcores = __builtin_popcountll(coremask);

For what Patrick needs: 
	uint32_t lcore_enabled_pos = __builtin_popcountll(coremask & RTE_LEN2MASK(lcore_index));

Regards,
Cristian

-----Original Message-----
From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Richardson, Bruce
Sent: Thursday, June 12, 2014 12:28 AM
To: Thomas Monjalon
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH] Add an API to query enabled core index

> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> Sent: Wednesday, June 11, 2014 3:50 PM
> To: Richardson, Bruce
> Cc: Lu, Patrick; dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] Add an API to query enabled core index
> 
> 2014-06-11 21:57, Richardson, Bruce:
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Thomas Monjalon
> > > 2014-06-11 13:45, Patrick Lu:
> > > > The new API rte_lcore_id2() will return an index from enabled lcores
> > > > starting from zero.
> > >
> > > 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.
> 
> I think it would be not easy to distinguish id and index. So I prefer
> hwid/index. And lcore is more precise than core.
> 

The function is already called "rte_lcore_id()" so there is no need to change it to make it an "lcore" function. That function has been around for a long time and is commonly used, so I'd prefer it not be changed unless it really is necessary. "rte_lcore_index" is a sufficiently different function name, in my opinion. The API documentation should clear up any confusion for the user anyway.
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