[Starlingx-discuss] CPU Affinity Kernel Patch

Jones, Bruce E bruce.e.jones at intel.com
Wed Mar 4 19:49:41 UTC 2020


+ StarlingX community

James, thank you!

          brucej

-----Original Message-----
From: Gauld, James [mailto:James.Gauld at windriver.com] 
Sent: Wednesday, March 4, 2020 8:21 AM
To: Somerville, Jim <Jim.Somerville at windriver.com>; Wold, Saul <saul.wold at intel.com>; Rowsell, Brent <Brent.Rowsell at windriver.com>; Jones, Bruce E <bruce.e.jones at intel.com>
Subject: RE: CPU Affinity Kernel Patch

Regarding CPU affinity specific configuration:

We need to keep the functionality provided by the following kernel patches:
- affine-compute-kernel-threads.patch
- Affine-irqs-and-workqueues-with-kthread_cpus.patch

These ensure kernel threads and all IRQs get the specified 'kthread_cpus=<cpulist>' kernel option at boot, and IRQs have this affinity as new devices are inserted.

In addition to the above, we configure settings at runtime via:
workqueue settings for writeback and virtual devices,
  /sys/bus/workqueue/devices/writeback/cpumask and  /sys/bus/virtual/workqueue/cpumask 

irq affinity settings for pci devices,
  /proc/irq/*/smp_affinity_list

-jim

-----Original Message-----
From: Jim Somerville [mailto:jim.somerville at windriver.com]
Sent: March-03-20 3:18 PM
To: Saul Wold; Rowsell, Brent; Jones, Bruce E; Gauld, James
Subject: Re: CPU Affinity Kernel Patch

I'm adding the other Jim, our cpu affinity guy.

-Jim

On 2020-03-03 3:11 p.m., Saul Wold wrote:
> 
> Hi Jim,
> 
> As we are moving to CentOS8 and the 4.18 kernel, I wanted to 
> double/triple check regarding the CPU affinity work.  I seem to recall 
> that StarlingX now uses the /sys workqueue masks. We we still need the 
> kernel patches?
> 
> I hope this is making some sense.
> 
> Thanks
> Sau!


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