topic Re: Kernel driver lock down processor in Operating System - HP-UX

Kernel driver lock down processor

Jon Ashburn — Wed, 09 Nov 2005 13:40:06 GMT

On hpux 11i v1 (11.11) is it possible to have
a given kernel driver for a PCI card only execute
on one CPU in an SMP system? Is there a system
call into the kernel that can affect the scheduler to only execute this drivers kernel threads (ISR and/or user context) on a given CPU in an SMP system?

Re: Kernel driver lock down processor

Steven E. Protter — Wed, 09 Nov 2005 14:13:38 GMT

Probably its possible. Problem would be that the OS is pretty good at deciding what happens on what CPU and this plan would defeat that.

I'm pretty sure you'd have to write it yourself.

SEP

Re: Kernel driver lock down processor

Ted Buis — Thu, 10 Nov 2005 10:26:16 GMT

My belief is that this is possible with psets, but I have never tried it. The logic is that if the interrupts occur frequently enough it is best to keep the context on a single CPU to take advantage of the processors cache. Check it out at:

http://h20293.www2.hp.com/portal/swdepot/displayProductInfo.do?productNumber=PSETS

Or also check www.docs.hp.com for psets.

Re: Kernel driver lock down processor

Ted Buis — Thu, 10 Nov 2005 10:30:20 GMT

From http://docs.hp.com/en/5185-4322/5185-4322.pdf :

"Real time applications expect somewhat deterministic responses or workload completion times, and hence want zero-to-minimal interference from other running applications in the system. In the past, there was no way to achieve this, so customers set up separate systems for real-time applications. With processor sets, however, customers can now use a single system to achieve the same objectives. Within the system, they can configure a processor set with the required number of processors and bind only the real-time application to that
processor set."

Re: Kernel driver lock down processor

Ted Buis — Thu, 10 Nov 2005 10:35:43 GMT

Robert F. Sauers addresses using psets with interrupts in his book "HP-UX 11i Tuning and Performance" on pages 188-189.