On Thu, 30 Nov 2006 12:03:15 +0100 Ingo Molnar <[EMAIL PROTECTED]> wrote:
> > * Gautham R Shenoy <[EMAIL PROTECTED]> wrote: > > > a) cpufreq maintain's it's own cpumask in the variable > > policy->affected_cpus and says : If a frequency change is issued to > > any one of the cpu's in the affected_cpus mask, you change frequency > > on all cpus in the mask. So this needs to be consistent with > > cpu_online map and hence cpu hotplug aware. Furthermore, we don't want > > cpus in this mask to go down when we are trying to change frequencies > > on them. The function which drives the frequency change in > > cpufreq-core is cpufreq_driver_target and it needs cpu-hotplug > > protection. > > couldnt this complexity be radically simplified by having new kernel > infrastructure that does something like: > > " 'gather' all CPUs mentioned in <mask> via scheduling a separate > helper-kthread on every CPU that <mask> specifies, disable all > interrupts, and execute function <fn> once all CPUs have been > 'gathered' - and release all CPUs once <fn> has executed on each of > them." > > ? How does this differ from stop_machine_run(), which hot-unplug presently uses? > This would be done totally serialized and while holding the hotplug > lock, so no CPU could go away or arrive while this operation is going > on. You said "the hotplug lock". That is the problem. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/