[dpdk-dev] [PATCH v5 0/2] Balanced allocation of hugepages

[Jerin Jacob]

-----Original Message-----
> Date: Wed, 21 Jun 2017 11:58:12 +0200
> From: Thomas Monjalon <thomas at monjalon.net>
> To: Jerin Jacob <jerin.jacob at caviumnetworks.com>
> Cc: Sergio Gonzalez Monroy <sergio.gonzalez.monroy at intel.com>, Hemant
>  Agrawal <hemant.agrawal at nxp.com>, Ilya Maximets <i.maximets at samsung.com>,
>  dev at dpdk.org, Bruce Richardson <bruce.richardson at intel.com>, David
>  Marchand <david.marchand at 6wind.com>, Heetae Ahn
>  <heetae82.ahn at samsung.com>, Yuanhan Liu <yliu at fridaylinux.org>, Jianfeng
>  Tan <jianfeng.tan at intel.com>, Neil Horman <nhorman at tuxdriver.com>, Yulong
>  Pei <yulong.pei at intel.com>
> Subject: Re: [PATCH v5 0/2] Balanced allocation of hugepages
> 
> 21/06/2017 11:27, Jerin Jacob:
> > -----Original Message-----
> > > Date: Wed, 21 Jun 2017 10:49:14 +0200
> > > From: Thomas Monjalon <thomas at monjalon.net>
> > > To: Jerin Jacob <jerin.jacob at caviumnetworks.com>
> > > Cc: Sergio Gonzalez Monroy <sergio.gonzalez.monroy at intel.com>, Hemant
> > >  Agrawal <hemant.agrawal at nxp.com>, Ilya Maximets <i.maximets at samsung.com>,
> > >  dev at dpdk.org, Bruce Richardson <bruce.richardson at intel.com>, David
> > >  Marchand <david.marchand at 6wind.com>, Heetae Ahn
> > >  <heetae82.ahn at samsung.com>, Yuanhan Liu <yliu at fridaylinux.org>, Jianfeng
> > >  Tan <jianfeng.tan at intel.com>, Neil Horman <nhorman at tuxdriver.com>, Yulong
> > >  Pei <yulong.pei at intel.com>
> > > Subject: Re: [PATCH v5 0/2] Balanced allocation of hugepages
> > > 
> > > 21/06/2017 10:41, Jerin Jacob:
> > > > > > 1. There are many machines (arm/ppc), which do not support NUMA.
> > > > > > 
> > > > > > https://wiki.linaro.org/LEG/Engineering/Kernel/NUMA
> > > > > > 
> > > > > 
> > > > > I did find that link too, last modified 4 years ago.
> > > > > Despite that, I could not find any ARM references in libnuma sources, but
> > > > > Jerin proved that there is support for it.
> > > > > 
> > > > > http://oss.sgi.com/projects/libnuma/
> > > > > https://github.com/numactl/numactl
> > > > 
> > > > Those Linaro links are very old. ARM64 NUMA supported has been added in 4.7 kernel.
> > > > I guess we are talking about build time time dependency with libnuma here.
> > > > Correct? I think, Even with old arm64 kernel(< 4.6), You can build against
> > > > libnuma if it is present in rootfs. Just that at runtime, it will return
> > > > NUMA support not available. Correct?
> > > > 
> > > > How hard is detect the presence of "numaif.h" if existing build system does not
> > > > support it? If it trivial, we can enable RTE_LIBRTE_EAL_NUMA_AWARE_HUGEPAGES
> > > > if build environment has "numaif.h".
> > > > 
> > > > Some example in linux kernel build system:
> > > > http://lxr.linux.no/linux+v4.10.1/scripts/gcc-goto.sh
> > > 
> > > I think we should not try to detect numaif.h, because it should be
> > > an error on platform supporting NUMA.
> > 
> > I have installed libnuma on a NUMA and non NUMA machine.
> > Compiled and ran following code on those machine and it could detect
> > the numa availability. Could you add more details on the "error on
> > platform supporting NUMA".
> 
> I was saying that we do not need to detect NUMA.
> If we are building DPDK for a NUMA architecture and libnuma is not
> available, then it will be a problem that the user must catch.
> The easiest way to catch it, is to fail on the include of numaif.h.

libnuma is not really _architecture_ depended.

Ilya Maximets patch disables NUMA support in common arm64 config.I
think, It is not correct, We should not disable on any archs generic config.

IMO, It should be enabled by default in common config and then we can
detect the presence of numaif.h, if not available OR a target does not need it
explicitly, proceed with disabling
RTE_LIBRTE_EAL_NUMA_AWARE_HUGEPAGES. I think, That is more portable.

No strong opinion on "failing the build" vs "printing a warning" in the
absence of numaif.h