On 10/3/07, Paul Jackson <[EMAIL PROTECTED]> wrote: > > Yes, something in user space has to do it. It's part of the > kernel-user cpuset API. If you change a cpuset's 'cpus', then > you have to rewrite each pid in its 'tasks' file back to that > 'tasks' file in order to get that 'cpus' change to be applied > to the task struct cpus_allowed of each task, and thereby visible > to the scheduler.
What's the rationale for this? Given that later in cpusets.txt you say: >If hotplug functionality is used >to remove all the CPUs that are currently assigned to a cpuset, >then the kernel will automatically update the cpus_allowed of all >tasks attached to CPUs in that cpuset to allow all CPUs why can't the same thing be done when changing the 'cpus' file manually. What's wrong with, in update_cpumask(), doing a loop across all members of the cgroup and updating their cpus_allowed fields? The existing cpusets API is broken, since a new child can always be forked between reading the tasks file and doing the writes. Paul - 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/
