DPDK on isolated cores but I still see interrupts

DPDK on isolated cores but I still see interrupts

[Antonio Di Bacco]

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I am trying to run a DPDK application on x86_64 Machine (Ubuntu 20.04) on
isolated cores.
I expected not to have interrupts on isolated cores but I still have a lot
of CAL (*Function call interrupts*) interrupts and LOC interrupts (*Local
timer interrupts*). Is there any setting in DPDK to stop those too?

Regards.

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RE: DPDK on isolated cores but I still see interrupts

[Kinsella, Ray]

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Can you supply “cat /proc/cmdline” please?

Ray K

From: Antonio Di Bacco <a.dibacco.ks@gmail.com>
Sent: Tuesday 1 March 2022 14:52
To: users@dpdk.org
Subject: DPDK on isolated cores but I still see interrupts

I am trying to run a DPDK application on x86_64 Machine (Ubuntu 20.04) on isolated cores.
I expected not to have interrupts on isolated cores but I still have a lot of CAL (Function call interrupts) interrupts and LOC interrupts (Local timer interrupts). Is there any setting in DPDK to stop those too?

Regards.

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Re: DPDK on isolated cores but I still see interrupts

[Cliff Burdick]

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One thing you can try is using the irqaffinity boot parameter to force
interrupts onto your non-isolated cores: For timer interrupts you can try
running in NO_HZ_FULL mode, but that may not work if you have other
userspace processes running on those cores. It might be worth confirming
that the interrupts are actually causing noticeable problems first before
trying to move the interrupts.

On Tue, Mar 1, 2022 at 6:52 AM Antonio Di Bacco <a.dibacco.ks@gmail.com>
wrote:

> I am trying to run a DPDK application on x86_64 Machine (Ubuntu 20.04) on
> isolated cores.
> I expected not to have interrupts on isolated cores but I still have a lot
> of CAL (*Function call interrupts*) interrupts and LOC interrupts (*Local
> timer interrupts*). Is there any setting in DPDK to stop those too?
>
> Regards.
>

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Re: DPDK on isolated cores but I still see interrupts

[Stephen Hemminger]

On Tue, 1 Mar 2022 15:16:32 +0000
"Kinsella, Ray" <ray.kinsella@intel.com> wrote:

> Can you supply “cat /proc/cmdline” please?
> 
> Ray K
> 
> From: Antonio Di Bacco <a.dibacco.ks@gmail.com>
> Sent: Tuesday 1 March 2022 14:52
> To: users@dpdk.org
> Subject: DPDK on isolated cores but I still see interrupts
> 
> I am trying to run a DPDK application on x86_64 Machine (Ubuntu 20.04) on isolated cores.
> I expected not to have interrupts on isolated cores but I still have a lot of CAL (Function call interrupts) interrupts and LOC interrupts (Local timer interrupts). Is there any setting in DPDK to stop those too?
> 
> Regards.

Some other notes:
  - don't use CPU 0. The kernel needs/wants to run things there
  - You may need to change softirq and workqueue settings (see /sys/devices/virtual/workqueue)