> On 18 Mar 2015, at 16:53, Traynor, Kevin <kevin.tray...@intel.com> wrote:
>
>>
>> -----Original Message-----
>> From: Daniele Di Proietto [mailto:diproiet...@vmware.com]
>> Sent: Monday, March 16, 2015 6:16 PM
>> To: Traynor, Kevin
>> Cc: dev@openvswitch.org
>> Subject: Re: [ovs-dev] [PATCH 0/6] DPDK: simplify configuration
>>
>>
>>> On 16 Mar 2015, at 15:18, Traynor, Kevin <kevin.tray...@intel.com> wrote:
>>>
>>>> -----Original Message-----
>>>> From: dev [mailto:dev-boun...@openvswitch.org] On Behalf Of Daniele Di
>>>> Proietto
>>>> Sent: Thursday, March 12, 2015 6:05 PM
>>>> To: dev@openvswitch.org
>>>> Subject: [ovs-dev] [PATCH 0/6] DPDK: simplify configuration
>>>>
>>>> This series improves OVS configuration with DPDK in three ways:
>>>>
>>>> * netdev-dpdk is patched to work on smaller systems (without 1GB
>> hugepages)
>>>> or with smaller NICs (without lots of transmission queues).
>>>> * the 'other_config:nonpmd-cpu-mask' key is introduced: it can be used to
>>>> limit OVS non PMD threads to a particular set of cores.
>>>> * the 'other_config:n-pmd-cores' key is introduced: it allows setting the
>>>> number of PMD threads without specifing a CPU mask.
>>>
>>> Hi, I've reviewed this patchset - few comments/questions on it…
>>
>> Hi Kevin, thanks
>>
>>> I haven't tested yet - but I'm wondering what is the impact to the dpdk -c
>>> parameter. Is it no longer used for OVS?
>>>
>>
>> Yes, that’s correct. It should have no impact on OVS. I think we
>> should also provide a default, i.e. generate the parameters passed to
>> dpdk_eal_init at some point.
>>
>>> At present the NON_PMD_CORE_ID define overrides the db settings (which is
>>> clearly documented). Is it needed now that a db key is available? Perhaps
>>> it would make things simpler that the define is overridden when a key is
>>> specified?
>>>
>>
>> We check NON_PMD_CORE_ID often in the fast path. I would prefer leaving it
>> as
>> it is right now and removing this limitation later, making sure that it has
>> no
>> impact on performance.
>
> Hi, I've tested the core pinning. Everything worked as I expected with a
> couple of exceptions. There was no noticeable negative effect on datapath
> performance.
>
> - the NON_PMD_CORE_ID is used *in addition* to the mask for nonpmd's - I
> think
> this should get a mention in the docs.
I mentioned it in vswitchd/vswitch.xml:
<p>
Please note that core 0 (NON_PMD_CORE_ID in the code) is always used
for non PMD threads, even if unset in this mask.
</p>
and in INSTALL.DPDK.md:
`ovs-vsctl set Open_vSwitch . other_config:nonpmd-cpu-mask=<hex string>`
The above command will limit OVS non PMD threads on the CPU set specified
by the hex string. Please note that core 0 is always used by non PMD
threads, even if it is unset in this mask. For more information,
please refer to `man ovs-vswitchd.conf.db`
I thought it was clear enough, but we can always improve it
> - I haven't done it before, so I'm not sure if it's related to these changes,
> but I wasn't able to get pmd's setup on the second socket. Getting this
> error "dpif_netdev|ERR|Cannot create pmd threads due to out of unpinned
> cores on numa node”.
If you’re trying to use a NIC attached to NUMA socket 0 and you’re specifying
a CPU mask without any core attached to NUMA socket 0, then the error makes
sense.
If you specify a CPU mask I expect that you know what you’re doing, you know
about
NUMA and stuff.
To prevent this kind of errors the series introduces the far simpler
’n-pmd-cores’
parameter: the user doesn’t need to be aware of the NUMA configuration at all.
Does this make sense?
> - There is still a few requirements regarding the -c option as it's not
> completely 'don't care' now. e.g. it can't be set to 0. These would be
> redundant if you do remove from it the cmd line - if they end up staying
> I can update the docs.
You’re right, it cannot be zero. I was hoping to remove it anyway.
Thanks for the testing,
Daniele
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