Re: [dpdk-dev] [PATCH v8 2/2] config: enable vhost numa awareness by default

[Hemant Agrawal <hemant.agrawal@nxp.com>]

On 6/27/2017 3:29 PM, Jerin Jacob wrote:
> -----Original Message-----
>> Date: Tue, 27 Jun 2017 15:11:07 +0530
>> From: Hemant Agrawal <hemant.agrawal@nxp.com>
>> To: Thomas Monjalon <thomas@monjalon.net>
>> CC: Ilya Maximets <i.maximets@samsung.com>, dev@dpdk.org, David Marchand
>>  <david.marchand@6wind.com>, Sergio Gonzalez Monroy
>>  <sergio.gonzalez.monroy@intel.com>, Heetae Ahn <heetae82.ahn@samsung.com>,
>>  Yuanhan Liu <yliu@fridaylinux.org>, Jianfeng Tan <jianfeng.tan@intel.com>,
>>  Neil Horman <nhorman@tuxdriver.com>, Yulong Pei <yulong.pei@intel.com>,
>>  Bruce Richardson <bruce.richardson@intel.com>, Jerin Jacob
>>  <jerin.jacob@caviumnetworks.com>
>> Subject: Re: [PATCH v8 2/2] config: enable vhost numa awareness by default
>> User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101
>>  Thunderbird/45.8.0
>>
>> On 6/27/2017 2:51 PM, Thomas Monjalon wrote:
>>> 27/06/2017 11:18, Hemant Agrawal:
>>>> On 6/27/2017 2:16 PM, Ilya Maximets wrote:
>>>>> It is safe to enable LIBRTE_VHOST_NUMA by default for all
>>>>> configurations where libnuma is already a default dependency.
>>>>>
>>>>> Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
>>>>> ---
>>>>>  config/common_linuxapp                    | 1 +
>>>>>  config/defconfig_arm-armv7a-linuxapp-gcc  | 1 +
>>>>>  config/defconfig_arm64-dpaa2-linuxapp-gcc | 1 +
>>>>>  3 files changed, 3 insertions(+)
>>> [...]
>>>>> --- a/config/defconfig_arm64-dpaa2-linuxapp-gcc
>>>>> +++ b/config/defconfig_arm64-dpaa2-linuxapp-gcc
>>>>> @@ -47,6 +47,7 @@ CONFIG_RTE_PKTMBUF_HEADROOM=256
>>>>>
>>>>>  # Doesn't support NUMA
>>>>>  CONFIG_RTE_EAL_NUMA_AWARE_HUGEPAGES=y
>>>>> +CONFIG_RTE_LIBRTE_VHOST_NUMA=n
>>>>>
>>>>>  #
>>>>>  # Compile Support Libraries for DPAA2
>>>>>
>>>>
>>>> -1
>>>> It should also be disabled for generic ARM64. This patch is breaking
>>>> generic arm64 config tests on our platforms and creating a unnecessary
>>>> dependency.
>>>
>>> What do you mean? Which ARM64 platform is it breaking?
>>> We can specifically disable it on more platforms.
>>>
>> Unlike x86, ARM only represent a core architecture.
>> Different platforms can integrate these cores differently in their SoCs.
>> The stock ARM v8 cores do not provide support for NUMA in my knowledge.
>
> A72 is just _an_ implementation of armv8. Not ARMv8 specification
> itself. By specification it is NUMA capable and there are NUMA
> implementation too.
>
>> Some vendors have modified ARM cores (e.g. Cavium) to support NUMA
>> architecture. However that is not a common phenomena.
>> NUMA config should not be default for generic ARM config. It should be
>> enabled only for architecture supporting it.
>
> It just an build time dependency. Right? If you feed the libnuma package,
> it will NON NUMA as well. Right? ARM64 libnuma package is already
> available for major distributions.

yes, libnuma will work for non-NUMA.
>
> My point is, I don't want to make arm64 generic config an exceptional case,
> If DPDK common config creates libnuma dependency then there is no reason
> for arm64 not have it. It is same for x86 and powerpc, non numa systems
> too. Right?

x86 and powerpc configs are single vendor based.
Common should be common and generic.

Why to create a unnecessary dependency, when we know that the support is 
not uniform?  It adds difficulties e.g. For the ARM cross compilation, 
will also have to cross compile libnuma-dev. Makefile will need a path 
for specifying the lib and include paths for libnuma and numa.h.


>
>>
>> So, *arm64-armv8a-linuxapp-gcc* config is being used by several vendors
>> include NXP. e.g. We use this config on several of our low end systems
>> (non-dpaa). Also, we use it when running in VM with virtio interfaces on all
>> of our different platforms (non-dpaa, dpaa1, dpaa2 etc).
>
> On the same note, arm64-armv8a-linuxapp-gcc used by other vendors for Server machines
> with NUMA and if want to keep creating new targets there is no end to it.
>
> How hard is to install libnuma on VM? There is already package for it.
>
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