Re: [PATCH] sched: Give cpusets exclusive control over sched domains (ie remove cpu_isolated_map)

Peter Zijlstra
2008-06-01T09:23:15Z

On Sat, 2008-05-31 at 12:12 -0700, Max Krasnyansky wrote:
>
> Paul Jackson wrote:
> > Max replied:
> >>> I did not see your reply. Did you send it to me or lkml?
> >> http://marc.info/?l=linux-kernel&m=121207910616332&w=2
> >
> > Ah - ok - I got that reply, and then lost track of it. My bad.
> >
> > Max wrote, in that earlier reply:
> >> Since we do not plan on supporting it I'd say lets get rid of it.
> >
> > This doesn't make sense to me. We don't just decree that we aren't
> > planning on supporting something that's already out there and being
> > used, and then remove it, on the grounds we aren't supporting it.
> >
> > Faceless beauracracies can get away with that ... we can do better.
>
> Ok. Let me ask you this. Would you be ok with a patch that exposes (via sysctl
> for example) scheduler balancer mask when cpusets are disabled ?
> In other words it will look something like this:
> - Rename cpu_isolated_map to sched_balancer_map
> - If cpusets are enabled
> o balancer map is compiled out or a noop
> o isolcpus= boot param is compiled out
>
> - If cpusets are disabled
> o balancer map can be changed via /proc/sys/kernel/sched_balancer_mask
> writing to it rebuilds scheduler domains
> cpus not in the mask will be put into NULL domain
> o isolcpus= boot param is available for compatibility
>
> Why do this ?
> Two reasons. It would not longer be a hack, it simply exposes scheduler
> feature that is not otherwise available without cpusets. And there is no
> conflict with sched domain management when cpusets are enabled. ie cpuset have
> exclusive control on domains).

Uhm, might be me but those two answers are not an answer to the question
posed.

Anyway, no, yuck! - let just get rid of it.