Hi
Thanks for the reply.
I control the smp affinity in userspace but I want to improve performance
on very high performance oriented machines.
I have several CPU (sockets) and it's important to create the queue vectors
"near" the memory of the socket of the CPU affinity.
the affinity_hint doesn't quite do the trick there.
I may use drivers with less queues than my cores count (like igb) and the
machines can even have 80 cores. so changing the weights is a good solution
but won't allways do the trick.
I generally use one queue affinity per core so no need to mask. but to make
my solution more general I'm willing to pass the cpu mask.
For example,
ethtool –set-cpu-mask <device> <queue> <cpu-mask> #to set the affinity
hint for the first 4
ethtool –set-cpu-mask eth1 0 1
ethtool –set-cpu-mask eth1 1 2
ethtool –set-cpu-mask eth1 2 4
Thanks,
Tal Abudi
On Sun, Mar 5, 2017 at 8:06 PM, Alexander Duyck <alexander.du...@gmail.com>
wrote:
> On Sun, Mar 5, 2017 at 8:47 AM, Tal Abudi <talab...@gmail.com> wrote:
> > Hi All
> >
> > I’m looking for a nice way to pass parameters (list of integers) to each
> > ixgbe interface.
> >
> > Creating /sys entries seems too complex and so I thought about ethtool.
>
> Why mess around with /sys when there is already
> /proc/irq/*/smp_affinity? It seems a bit convoluted to try to add an
> interface to set something that is then used by a user-space daemon to
> set something else that is already writable.
>
> > How can I pass private data (a list) to each nic with minimal driver code
> > change ?
>
> What you are talking about would be really invasive. In addition
> integers assume a single CPU mapping, or fewer than 32 CPUs. In most
> cases all affinities use a bitmask that is nr_cpus in size.
>
> > To clarify, I want to use a customized affinity hint with multi queue.
> >
> > For example, on a machine with 12 cores and RSS of 4 I want to set the
> > RX/TX queues to CPUs 8-11, It would look something like:
> >
> > ethtool –set-cpu eth0 8 9 10 11 #to set the affinity hint for the first
> 4
> > queues to cpus 8-11
> >
> > ethtool –set-channels eth0 combined 4 #Recreate 4 Rx/Tx vectors and use
> the
> > new and customized affinity hint.
> >
> > <Set the regular RX IRQ affinity to the same CPUs>
>
> I have what I believe would be a better suggestion.
>
> You could leave all 12 queues enabled, and should be able to limit RSS
> to 4 queues with ethtool -X eth0 equal 4, or if you really want to
> just restrict RSS to the last 4 queues you could do that by messing
> with the weights and just restricting the first 8 weights to 0, and
> the last 4 to 1. The only downside is non-RSS flows are still
> defaulted to queue 0.
>
> If you want to shuffle the queues around then it is just a matter of
> reprogramming the XPS maps "/sys/class/net/eth0/queues/tx-*/xps_cpus"
> and IRQ affinities so you could shift the maps around by 4 CPUs. That
> way queues 4-12 are serviced by CPUs 0-7, and queues 0-3 would be
> serviced by CPUs 8-11.
>
--
Best regards,
Tal Abudi
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