pm24.git/kernel/sched.c, branch v2.6.15

[PATCH] m68k: introduce setup_thread_stack() and end_of_stack()

2005-11-14T02:14:13Z

encapsulates the rest of arch-dependent operations with thread_info access. Two new helpers - setup_thread_stack() and end_of_stack(). For normal case the former consists of copying thread_info of parent to new thread_info and the latter returns pointer immediately past the end of thread_info. Signed-off-by: Al Viro Signed-off-by: Roman Zippel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] m68k: introduce task_thread_info

2005-11-14T02:14:13Z

new helper - task_thread_info(task). On platforms that have thread_info allocated separately (i.e. in default case) it simply returns task->thread_info. m68k wants (and for good reasons) to embed its thread_info into task_struct. So it will (in later patch) have task_thread_info() of its own. For now we just add a macro for generic case and convert existing instances of its body in core kernel to uses of new macro. Obviously safe - all normal architectures get the same preprocessor output they used to get. Signed-off-by: Al Viro Signed-off-by: Roman Zippel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] optimize activate_task()

2005-11-10T00:07:44Z

recalc_task_prio() is called from activate_task() to calculate dynamic priority and interactive credit for the activating task. For real-time scheduling process, all that dynamic calculation is thrown away at the end because rt priority is fixed. Patch to optimize recalc_task_prio() away for rt processes. Signed-off-by: Ken Chen Acked-by: Ingo Molnar Cc: Nick Piggin Cc: Con Kolivas Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] sched: resched and cpu_idle rework

2005-11-09T15:56:33Z

Make some changes to the NEED_RESCHED and POLLING_NRFLAG to reduce confusion, and make their semantics rigid. Improves efficiency of resched_task and some cpu_idle routines. * In resched_task: - TIF_NEED_RESCHED is only cleared with the task's runqueue lock held, and as we hold it during resched_task, then there is no need for an atomic test and set there. The only other time this should be set is when the task's quantum expires, in the timer interrupt - this is protected against because the rq lock is irq-safe. - If TIF_NEED_RESCHED is set, then we don't need to do anything. It won't get unset until the task get's schedule()d off. - If we are running on the same CPU as the task we resched, then set TIF_NEED_RESCHED and no further action is required. - If we are running on another CPU, and TIF_POLLING_NRFLAG is *not* set after TIF_NEED_RESCHED has been set, then we need to send an IPI. Using these rules, we are able to remove the test and set operation in resched_task, and make clear the previously vague semantics of POLLING_NRFLAG. * In idle routines: - Enter cpu_idle with preempt disabled. When the need_resched() condition becomes true, explicitly call schedule(). This makes things a bit clearer (IMO), but haven't updated all architectures yet. - Many do a test and clear of TIF_NEED_RESCHED for some reason. According to the resched_task rules, this isn't needed (and actually breaks the assumption that TIF_NEED_RESCHED is only cleared with the runqueue lock held). So remove that. Generally one less locked memory op when switching to the idle thread. - Many idle routines clear TIF_POLLING_NRFLAG, and only set it in the inner most polling idle loops. The above resched_task semantics allow it to be set until before the last time need_resched() is checked before going into a halt requiring interrupt wakeup. Many idle routines simply never enter such a halt, and so POLLING_NRFLAG can be always left set, completely eliminating resched IPIs when rescheduling the idle task. POLLING_NRFLAG width can be increased, to reduce the chance of resched IPIs. Signed-off-by: Nick Piggin Cc: Ingo Molnar Cc: Con Kolivas Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] sched: consider migration thread with smp nice

2005-11-09T15:56:32Z

The intermittent scheduling of the migration thread at ultra high priority makes the smp nice handling see that runqueue as being heavily loaded. The migration thread itself actually handles the balancing so its influence on priority balancing should be ignored. Signed-off-by: Con Kolivas Cc: Ingo Molnar Cc: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] sched: correct smp_nice_bias

2005-11-09T15:56:32Z

The priority biasing was off by mutliplying the total load by the total priority bias and this ruins the ratio of loads between runqueues. This patch should correct the ratios of loads between runqueues to be proportional to overall load. -2nd attempt. From: Dave Kleikamp This patch fixes a divide-by-zero error that I hit on a two-way i386 machine. rq->nr_running is tested to be non-zero, but may change by the time it is used in the division. Saving the value to a local variable ensures that the same value that is checked is used in the division. Signed-off-by: Con Kolivas Signed-off-by: Dave Kleikamp Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] sched: smp nice bias busy queues on idle rebalance

2005-11-09T15:56:32Z

To intensify the 'nice' support across physical cpus on SMP we can bias the loads on idle rebalancing. To prevent idle rebalance from trying to pull tasks from queues that appear heavily loaded we only bias the load if there is more than one task running. Add some minor micro-optimisations and have only one return from __source_load and __target_load functions. Fix the fact that target_load was not biased by priority when type == 0. Signed-off-by: Con Kolivas Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] sched: account rt tasks in prio_bias()

2005-11-09T15:56:32Z

Real time tasks' effect on prio_bias should be based on their real time priority level instead of their static_prio which is based on nice. Signed-off-by: Con Kolivas Cc: Ingo Molnar Cc: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] sched: change prio bias only if queued

2005-11-09T15:56:32Z

prio_bias should only be adjusted in set_user_nice if p is actually currently queued. Signed-off-by: Con Kolivas Cc: Ingo Molnar Cc: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

[PATCH] sched: implement nice support across physical cpus on SMP

2005-11-09T15:56:32Z

This patch implements 'nice' support across physical cpus on SMP. It introduces an extra runqueue variable prio_bias which is the sum of the (inverted) static priorities of all the tasks on the runqueue. This is then used to bias busy rebalancing between runqueues to obtain good distribution of tasks of different nice values. By biasing the balancing only during busy rebalancing we can avoid having any significant loss of throughput by not affecting the carefully tuned idle balancing already in place. If all tasks are running at the same nice level this code should also have minimal effect. The code is optimised out in the !CONFIG_SMP case. Signed-off-by: Con Kolivas Cc: Ingo Molnar Cc: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds