[dpdk-dev] [PATCH v4 3/6] build: optional NUMA and cpu counts detection

[Bruce Richardson]

On Tue, Oct 27, 2020 at 03:50:46PM +0000, Juraj Linkeš wrote:
> 
> 
> > -----Original Message-----
> > From: Bruce Richardson <bruce.richardson at intel.com>
> > Sent: Tuesday, October 27, 2020 12:21 PM
> > To: Juraj Linkeš <juraj.linkes at pantheon.tech>
> > Cc: Ruifeng.Wang at arm.com; Honnappa.Nagarahalli at arm.com;
> > Phil.Yang at arm.com; vcchunga at amazon.com; Dharmik.Thakkar at arm.com;
> > jerinjacobk at gmail.com; hemant.agrawal at nxp.com; dev at dpdk.org
> > Subject: Re: [PATCH v4 3/6] build: optional NUMA and cpu counts detection
> > 
> > On Fri, Oct 23, 2020 at 04:48:05PM +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.linkes at pantheon.tech>
> > > ---
> > >  buildtools/get_cpu_count.py  |  7 ++++++
> > > buildtools/get_numa_count.py | 22 +++++++++++++++++
> > >  buildtools/meson.build       |  2 ++
> > >  config/meson.build           | 48 ++++++++++++++++++++++++++++++++++--
> > >  meson_options.txt            |  8 +++---
> > >  5 files changed, 81 insertions(+), 6 deletions(-)  create mode 100644
> > > buildtools/get_cpu_count.py  create mode 100644
> > > buildtools/get_numa_count.py
> > >
> > > diff --git a/buildtools/get_cpu_count.py b/buildtools/get_cpu_count.py
> > > new file mode 100644 index 000000000..386f85f8b
> > > --- /dev/null
> > > +++ b/buildtools/get_cpu_count.py
> > > @@ -0,0 +1,7 @@
> > > +#!/usr/bin/python3
> > > +# SPDX-License-Identifier: BSD-3-Clause # Copyright (c) 2020
> > > +PANTHEON.tech s.r.o.
> > > +
> > > +import os
> > > +
> > > +print(os.cpu_count())
> > > diff --git a/buildtools/get_numa_count.py
> > > b/buildtools/get_numa_count.py new file mode 100644 index
> > > 000000000..f0c49973a
> > > --- /dev/null
> > > +++ b/buildtools/get_numa_count.py
> > > @@ -0,0 +1,22 @@
> > > +#!/usr/bin/python3
> > > +# SPDX-License-Identifier: BSD-3-Clause # Copyright (c) 2020
> > > +PANTHEON.tech s.r.o.
> > > +
> > > +import ctypes
> > > +import glob
> > > +import os
> > > +import subprocess
> > > +
> > > +if os.name == 'posix':
> > > +    if os.path.isdir('/sys/devices/system/node'):
> > > +        print(len(glob.glob('/sys/devices/system/node/node*')))
> > > +    else:
> > > +        print(subprocess.run(['sysctl', 'vm.ndomains'],
> > > +capture_output=True).stdout)
> > 
> > I think you can shorten this, by just calling subprocess.run and not capturing
> > anything, in which case the stdout will be printed as normal.
> > 
> > 	subprocess.run(['sysctl', 'vm.ndomains'])
> > 
> 
> This will also print out the resulting object (e.g. CompletedProcess(args=['ls', '-ls', '/sys/devices/system/node'], returncode=0)), but an assignment will take care of that. I'll make the change.
> 

Not unless you are running interactively in the python3 REPL.
For example:

$ cat test_meminfo.py
#! /usr/bin/env python3

from subprocess import run
run(['cat', '/proc/meminfo'])

$ python3 test_meminfo.py | tail -n 5
Hugepagesize:       2048 kB
Hugetlb:        17825792 kB
DirectMap4k:     1056788 kB
DirectMap2M:     9758720 kB
DirectMap1G:    88080384 kB

$