[dpdk-dev] [PATCH 2/2] build: find max lcore programmatically

[Juraj Linkeš]

> -----Original Message-----
> From: dev <dev-bounces at dpdk.org> On Behalf Of Dharmik Thakkar
> Sent: Wednesday, August 26, 2020 6:56 AM
> To: Jerin Jacob <jerinjacobk at gmail.com>
> Cc: thomas at monjalon.net; dpdk-dev <dev at dpdk.org>; nd <nd at arm.com>
> Subject: Re: [dpdk-dev] [PATCH 2/2] build: find max lcore programmatically
> 
> 
> 
> > On Aug 25, 2020, at 11:47 PM, Jerin Jacob <jerinjacobk at gmail.com> wrote:
> >
> > On Wed, Aug 26, 2020 at 2:44 AM Dharmik Thakkar
> <dharmik.thakkar at arm.com> wrote:
> >>
> >> For Arm, RTE_MAX_LCORE is hard-coded into the config. It leads to
> >> incorrect RTE_MAX_LCORE when machines have same Implemener and part
> >> number but different number of CPUs.
> >> For x86, RTE_MAX_LCORE is always set to 128 (using the value set in
> >> meson_options.txt)
> >>
> >> Use python script to find max lcore when using native build to
> >> correctly set RTE_MAX_LCORE.
> >
> > We may need to build on the native arm64 machine and use it on another
> > arm64 machine(Just like x86).
> > So I think, at least for default config(which will be used by
> > distribution) to support max
> > lcores as fixed. I am not sure this patch changes those aspects or
> > not? Please check.
> 
> This patch does *not* affect ‘default’ build type and cross-compilation.
> 
> >
> >>
> >> Signed-off-by: Dharmik Thakkar <dharmik.thakkar at arm.com>
> >> Reviewed-by: Ruifeng Wang <ruifeng.wang at arm.com>
> >> ---
> >> config/get_max_lcores.py | 13 +++++++++++++
> >> config/meson.build       | 13 ++++++++++++-
> >> 2 files changed, 25 insertions(+), 1 deletion(-) create mode 100755
> >> config/get_max_lcores.py
> >>
> >> diff --git a/config/get_max_lcores.py b/config/get_max_lcores.py new
> >> file mode 100755 index 000000000000..ebf1c7efdadd
> >> --- /dev/null
> >> +++ b/config/get_max_lcores.py
> >> @@ -0,0 +1,13 @@
> >> +#!/usr/bin/python3
> >> +# SPDX-License-Identifier: BSD-3-Clause # Copyright(c) 2020 Arm
> >> +Limited
> >> +
> >> +import os
> >> +
> >> +max_lcores = []
> >> +
> >> +nCPU = os.cpu_count()
> >> +
> >> +max_lcores.append(str(nCPU & 0xFFF))             # Number of CPUs
> >> +
> >> +print(' '.join(max_lcores))
> >> diff --git a/config/meson.build b/config/meson.build index
> >> 6996e5cbeaa5..80c05bc15d2f 100644
> >> --- a/config/meson.build
> >> +++ b/config/meson.build
> >> @@ -237,11 +237,22 @@ else # for 32-bit we need smaller reserved memory
> areas
> >>        dpdk_conf.set('RTE_MAX_MEM_MB', 2048) endif
> >>
> >> -
> >> compile_time_cpuflags = []
> >> subdir(arch_subdir)
> >> dpdk_conf.set('RTE_COMPILE_TIME_CPUFLAGS',
> >> ','.join(compile_time_cpuflags))
> >>
> >> +# set max lcores
> >> +if machine != 'default' and not meson.is_cross_build()
> >> +       # The script returns max lcores
> >> +       params = files('get_max_lcores.py')
> >> +       cmd_out = run_command(params)

Have you considered running just a shell command, such as "nproc --all"?

> >> +       if cmd_out.returncode() == 0
> >> +               cmd_lcore = cmd_out.stdout().to_lower().strip().split(' ')
> >> +       endif
> >> +       max_lcore = cmd_lcore[0].to_int()
> >> +       dpdk_conf.set('RTE_MAX_LCORE', max_lcore) endif
> >> +
> >> # set the install path for the drivers
> >> dpdk_conf.set_quoted('RTE_EAL_PMD_PATH', eal_pmd_path)
> >>
> >> --
> >> 2.17.1
> >>