Re: [PATCH RFC] ioctl based CAT interface

Marcelo Tosatti
2015-11-13T17:33:26Z

On Fri, Nov 13, 2015 at 05:51:00PM +0100, Peter Zijlstra wrote:
> On Fri, Nov 13, 2015 at 02:39:33PM -0200, Marcelo Tosatti wrote:
> > + * * one tcrid entry can be in different locations
> > + * in different sockets.
>
> NAK on that without cpuset integration.
>
> I do not want freely migratable tasks having radically different
> performance profiles depending on which CPU they land.

Ok, so, configuration:

Socket-1 Socket-2

pinned thread-A with 100% L3 free
80% of L3
reserved

So it is a problem if a thread running on socket-2 is scheduled to
socket-1 because performance is radically different, fine.

Then one way to avoid that is to not allow freely migratable tasks
to move to Socket-1. Fine.

Then you want to use cpusets for that.

Can you fill in the blanks what is missing here?