Re: Question about CPU affinity for interrupts

[Livio Ricciulli <livio () metaflows com>]

Yes, sure.
On 03/11/2014 04:49 PM, Roger Campbell wrote:
> Thanks for the response Livio!  Should I avoid assigning an IRQ to a 
> hyper-thread for this task?
>
>
> On Tue, Mar 11, 2014 at 12:57 PM, Livio Ricciulli <livio () metaflows com 
> <mailto:livio () metaflows com>> wrote:
>
>     The driver usually copies the packets from the NIC to the memory
>     of the node (or hardware thread) where the IRQ' affinity is mapped.
>
>     If you do
>     numactl --hardware
>
>     You will see your memory architecture.
>     I am guessing all nodes use the same memory in your case; if so, I
>     would map the IRQ to the free CPUs. If not, see below:
>
>     If your NIC driver/chipset can do symmetric RSS, then you would
>     want to map each interrupt to a node with the smallest distance to
>     the node where Snort will consume the packets from that IRQ. If
>     your NIC cannot do RSS, it does not matter since the packets from
>     each interrupt will be consumed by all Snort processes.
>
>     Livio.
>
>
>     On 03/10/2014 07:38 PM, Roger Campbell wrote:
> >     Hi everyone, had a question about IRQs and PF_RING.
> >
> >     Currently I'm testing out PF_RING and snort 2.9.6 on a 1Gb/s link
> >     that usually tops out around 800Mb/s.  The system has 16 physical
> >     cores (32 Hyper-Threads).
> >
> >     If I run 8 snort instances in the format below, load is handled
> >     pretty well.
> >
> >     snort -R 1 --daq-dir=/usr/local/lib/daq --daq pfring --daq-mode
> >     passive --daq-var clusterid=10 --daq-var bindcpu=4 -c
> >     /IDS/snort/etc/snort.conf -l /IDS/snort/log1 -u snort -g snort -i
> >     eth4 -D
> >     snort -R 2 --daq-dir=/usr/local/lib/daq --daq pfring --daq-mode
> >     passive --daq-var clusterid=10 --daq-var bindcpu=6 -c
> >     /IDS/snort/etc/snort.conf -l /IDS/snort/log2 -u snort -g snort -i
> >     eth4 -D
> >     (continues using CPU 8,10,12,14,16,18)
> >
> >     I know that I should set CPU affinity for interrupts for each rx
> >     queue to a specific CPU or set of CPUs.  My question is, should I
> >     bind these to 8 free cores, or should I bind them to cores which
> >     are already hosting a snort process?
> >
> >     All of the IRQs are currently being processed by ksoftirqd/0 on
> >     CPU 0 which is not optimal.
> >
> >
> >
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