Hello, guys. I'm wondering why cpuset_cpus_allowed_fallback() is necessary. This is called from, e.g., try_to_wake_up()->select_task_rq() when none of the cpus in ->cpus_allowed is useable. The cpuset callback invokes do_set_cpus_allowed() w/ the cpuset's cpus_allowed. This was added by the following commit,
commit 9084bb8246ea935b98320554229e2f371f7f52fa Author: Oleg Nesterov <[email protected]> Date: Mon Mar 15 10:10:27 2010 +0100 sched: Make select_fallback_rq() cpuset friendly Introduce cpuset_cpus_allowed_fallback() helper to fix the cpuset problems with select_fallback_rq(). It can be called from any context and can't use any cpuset locks including task_lock(). It is called when the task doesn't have online cpus in ->cpus_allowed but ttwu/etc must be able to find a suitable cpu. .... The problem is, nothing's explaining what "the cpuset problems with select_fallback_rq()" are. Oleg, do you remember? Why do we need this? Thanks. -- tejun -- 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/
