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

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

On 6/27/2017 6:15 PM, Jerin Jacob wrote:
> -----Original Message-----
>> Date: Tue, 27 Jun 2017 17:47:44 +0530
>> From: Hemant Agrawal <hemant.agrawal@nxp.com>
>> To: Jerin Jacob <jerin.jacob@caviumnetworks.com>
>> CC: Thomas Monjalon <thomas@monjalon.net>, 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>
>> 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 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.
>
> Yes. What I understand by common is that it should work on functionality on _all_ the
> armv8 targets. If you don't include NUMA then it will have functionality issue
> with NUMA targets.
>
> The ARM64 Linux kernel took the similar approach. The default config has all
> options and NUMA is _enabled_ even it is not supported on A72.
>
> http://elixir.free-electrons.com/linux/latest/source/arch/arm64/configs/defconfig#L77
>

Ok!  Not able to think of any other issue for now.

>
>>
>> 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.
>
> Yes. I agree. Cross compilation needs additional step. On the other
> hand, If we don't include NUMA in common config, We need to add new targets on
> all new SoCs(like thunderx2). IMO, In order to reduce the config, I think,
> this is the better way.(and it is not hard to disable NUMA for cross
> compilation mode if not interested)
>
>>
>>
>>>
>>>>
>>>> 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.
>>>
>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>
>>
>