[dpdk-dev] [PATCH v12 09/14] build: optional NUMA and cpu counts detection

Thomas Monjalon thomas at monjalon.net
Mon Nov 16 10:23:50 CET 2020


16/11/2020 10:13, Bruce Richardson:
> On Mon, Nov 16, 2020 at 08:24:48AM +0100, Thomas Monjalon wrote:
> > 13/11/2020 15:31, Juraj Linkeš:
> > > +option('max_lcores', type: 'integer', value: 0,
> > > +	description: 'maximum number of cores/threads supported by EAL. Set to positive integer to overwrite per-arch or cross-compilation defaults. Set to -1 to detect the number of cores on the build machine.')
> > > +option('max_numa_nodes', type: 'integer', value: 0,
> > > +	description: 'maximum number of NUMA nodes supported by EAL. Set to positive integer to overwrite per-arch or cross-compilation defaults. Set to -1 to detect the number of numa nodes on the build machine.')
> > 
> > First comment: I don't like having so long description.
> > Second: I don't understand.
> > 
> > It is said the default value is 0 so I expect it means automatic detection.
> > But later it is said -1 is for detection. So ?
> > 
> Zero is for the "per-arch or cross-compilation default". This was discussed
> quite a bit in previous versions and this was te best compromise we could
> come up with. Having a default of auto-detect is definitely not something I
> think we should go with - just thinking of all the build CI jobs running on
> 2 or 4 core VMs! However, Juraj really felt there was value in having
> auto-detection, so it's set as a -1 value, which I'm ok with.

The problem is that I don't understand what 0 means.

> As I flagged in a previous mail thread, the whole config of DPDK builds is
> something we need to take a bigger look at in 21.02 and beyond.

Yes definitely.




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