[ovs-dev] [PATCH v3 3/3] netdev-dpdk: Autofill lcore coremask if absent

[Traynor, Kevin]

> -----Original Message-----
> From: dev [mailto:dev-bounces at openvswitch.org] On Behalf Of Aaron Conole
> Sent: Tuesday, January 19, 2016 1:28 PM
> To: Qiu, Michael
> Cc: dev at openvswitch.org; Flavio Leitner; Zoltan Kiss
> Subject: Re: [ovs-dev] [PATCH v3 3/3] netdev-dpdk: Autofill lcore coremask if
> absent
> 
> "Qiu, Michael" <michael.qiu at intel.com> writes:
> > On 1/14/2016 5:18 AM, Aaron Conole wrote:
> >> The user has control over the DPDK internal lcore coremask, but this
> >> parameter can be autofilled with a bit more intelligence. If the user
> >> does not fill this parameter in, we use the lowest set bit in the
> >> current task CPU affinity. Otherwise, we will reassign the current
> >> thread to the specified lcore mask, in addition to the dpdk lcore
> >> threads.
> >
> > It's not a good idea to use the lowest set bit in the current task CPU
> > affinity,
> >
> > I think numa info should be considered as the NIC could belongs to
> > different Socket.
> >
> > If remote socket, it will lead bad performance.
> 
> I agree with your concerns, but they are tuning and optimization. The
> point of defaults is to get something up and running "good enough."
> Without an auto-assigned coremask, the user is forced to pick one and
> that is something of an inconvenience just to try out DPDK. So we have a
> default mechanism in place to tide over the user.
> 
> This default exists to handle the case where the user does not tune
> appropriately to their system. See
> http://openvswitch.org/pipermail/dev/2015-December/063626.html for some
> additonal context. Also keep in mind, this is solely for the lcore
> threads - PMD threads have their own CPU mask.

+1

> 
> > Thanks,
> > Michael
> 
> Thanks for the review, Michael!
> 
> -Aaron
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