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SubjectRe: Inquiry: Should we remove "isolcpus= kernel boot option? (may have realtime uses)
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On Wed, 2008-06-04 at 11:29 -0700, Max Krasnyansky wrote:
>
> Paul Jackson wrote:
> > Andi wrote:
> >> Right now the system boot could put pages from some daemon in there before any
> >> cpusets are set up and there's no easy way to get them away again
> >
> > We (SGI) routinely handle that need with a custom init program,
> > invoked with the init= parameter to the booting kernel, which
> > sets up cpusets and then invokes the normal (real) init program
> > in a cpuset configured to exclude those CPUs and nodes which we
> > want to remain unloaded. For example, on a 256 CPU, 64 node
> > system, we might have init running on a single node of 4 CPUs,
> > and leave the remaining 63 nodes and 252 CPUs isolated from all
> > the usual user level daemons started by init.
> >
> > There is no need for additional kernel changes to accomplish this.
>
> You do not even need to replace /sbin/init for this, no ?
> Simply installing custom
> /etc/init.d/create_cpusets
> with priority 0
> # chkconfig: 12345 0 99
> will do the job.
>
> That script will move init itself into the appropriate cpuset and from then on
> everything will inherit it.

The advantage of using a replacement /sbin/init is that you execute
before the rest of userspace, unlike what you propose.



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