Re: Inquiry: Should we remove "isolcpus= kernel boot option? (mayhave realtime uses)

[Peter Zijlstra]

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.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/