Mailinglist Archive: opensuse-support (159 mails)

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Re: [opensuse-support] Leap 15 performance issue
On 2018-06-25 13:17, Bengt Gördén wrote:
Den 2018-06-25 kl. 11:56, skrev Carlos E. R.:
Interrupts are tied to a certain core?
I thought they were dynamically assigned to a non busy core.

Yes. Your right. I think I was a bit unclear. What I meant was that if
you have the need to redirect one interrupt source to a certain core it
can be done via smp-affinity. Normally you shouldn't need that but there
are cases where it is of great importance. The two cases I referred to
(router and DAW) is such cases. They are real time cases. Under heavy
load in a recording (audio) situation you do not want disturbance in any
way and as low latency as possible. In the case of router it's crucial
if you have a production system and you don't have an out-of-band
solution to access the router and the traffic is very high. We did this
in three different projects about 11-13 years ago where we showed that
10Gbit/s forwarding in a Linux router is possible. There we redirected
the ssh-port to CPU0 and the rest of the packets were handled by core
CPU1-CPU7 so that the control plane were separated from data plane.

I see :-)

But to get back to the "watch cat /proc/interrupts". It's to see were
the interrupts comes from.

Yes, it is a good idea.

Long ago, my computer was running very slow one day (perhaps SuSE 7.x).
The process "init" was very, very busy. Single core CPU. I don't
remember how I found out, but the modem was sending a flurry of
interrupts over the serial port. I power cycled the modem and problem
solved. :-)

It never happened again.

Cheers / Saludos,

Carlos E. R.
(from 42.3 x86_64 "Malachite" at Telcontar)

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