On Tue, Jul 06, 2021 at 08:56:37AM +0000, Juraj Linkeš wrote:
>
>
> > -----Original Message-----
> > From: Bruce Richardson <bruce.richard...@intel.com>
> > Sent: Tuesday, June 29, 2021 1:29 PM
> > To: Juraj Linkeš <juraj.lin...@pantheon.tech>
> > Cc: tho...@monjalon.net; david.march...@redhat.com;
> > honnappa.nagaraha...@arm.com; ruifeng.w...@arm.com;
> > ferruh.yi...@intel.com; jerinjac...@gmail.com; dev@dpdk.org
> > Subject: Re: [PATCH v4] build: optional NUMA and cpu counts detection
> >
> > On Tue, Jun 29, 2021 at 12:55:05PM +0200, Juraj Linkeš wrote:
> > > Add an option to automatically discover the host's numa and cpu counts
> > > and use those values for a non cross-build.
> > > Give users the option to override the per-arch default values or
> > > values from cross files by specifying them on the command line with
> > > -Dmax_lcores and -Dmax_numa_nodes.
> > >
> > > Signed-off-by: Juraj Linkeš <juraj.lin...@pantheon.tech>
> > > Reviewed-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>
> > > ---
> > Two very minor suggestions inline below.
> >
> > Acked-by: Bruce Richardson <bruce.richard...@intel.com>
> >
> > >
> > <snip>
> > > +max_lcores = get_option('max_lcores') if max_lcores == 'auto'
> >
> > Rather than "auto", would "detect" be a clearer name for this option value?
> >
> > <snip>
> > > +option('max_lcores', type: 'string', value: 'default', description:
> > > + 'Set maximum number of cores/threads supported by EAL. The
> > > +default is different per-arch. Set to auto to detect the number of cores
> > > on the
> > build machine.') option('max_numa_nodes', type: 'string', value: 'default',
> > description:
> > > + 'Set highest NUMA node supported by EAL. The default is
> > > +different per-arch. Set to auto to detect the highest numa node on
> > > +the build machine.')
> >
> > I'd put the explicit values of "default" and "auto"(or "detect") in quotes
> > "" to
> > make clear they are literal values.
> >
>
> Thanks, Bruce, I'll change it. I have one extra question now that I'm looking
> at the patch:
> What does subprocess.run(['sysctl', '-n', 'vm.ndomains'], check=False) return
> exactly? Is the the number of NUMA nodes (looks like it) or the highest NUMA
> node on the system (the highest number of all NUMA nodes)? I'm asking because
> of how NUMA works on P9:
> NUMA node0 CPU(s): 0-63
> NUMA node8 CPU(s): 64-127
> NUMA node252 CPU(s):
> NUMA node253 CPU(s):
> NUMA node254 CPU(s):
> NUMA node255 CPU(s):
>
> Here we need not just two NUMA nodes, but at least 9 (0-8). Linux and Windows
> should return the highest NUMA, not sure about FreeBSD. Or maybe we should
> return the highest NUMA on which there are actual CPUs?
I'm not sure, and I think to be really sure we'd need it tested on a P9
system. The help text for the sysctl node says "Number of physical memory
domains available", which would imply 2 in the case above. [However, we also
would need to find out how BSD numbers the domains, too, as it's possible
an OS could just call them 0 and 1, rather than 0 and 8 if it wanted to.]
In short, we'd need to test to be sure. Is FreeBSD on P9 a supported
config, and if so can the P9 maintainer perhaps help out with testing?
/Bruce
