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* [PATCH] m68k: introduce setup_thread_stack() and end_of_stack()Al Viro2005-11-141-2/+2
| | | | | | | | | | | | 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 <viro@parcelfarce.linux.theplanet.co.uk> Signed-off-by: Roman Zippel <zippel@linux-m68k.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] m68k: introduce task_thread_infoAl Viro2005-11-141-3/+3
| | | | | | | | | | | | | | | 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 <viro@parcelfarce.linux.theplanet.co.uk> Signed-off-by: Roman Zippel <zippel@linux-m68k.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] optimize activate_task()Chen, Kenneth W2005-11-101-1/+2
| | | | | | | | | | | | | | | 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 <kenneth.w.chen@intel.com> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Nick Piggin <piggin@cyberone.com.au> Cc: Con Kolivas <kernel@kolivas.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: resched and cpu_idle reworkNick Piggin2005-11-091-7/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <npiggin@suse.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Con Kolivas <kernel@kolivas.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: consider migration thread with smp niceCon Kolivas2005-11-091-9/+26
| | | | | | | | | | | | | 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 <kernel@kolivas.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: correct smp_nice_biasCon Kolivas2005-11-091-6/+8
| | | | | | | | | | | | | | | | | | | 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 <shaggy@austin.ibm.com> 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 <kernel@kolivas.org> Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: smp nice bias busy queues on idle rebalanceCon Kolivas2005-11-091-18/+23
| | | | | | | | | | | | | | | | 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 <kernel@kolivas.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: account rt tasks in prio_bias()Con Kolivas2005-11-091-8/+14
| | | | | | | | | | | 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 <kernel@kolivas.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: change prio bias only if queuedCon Kolivas2005-11-091-5/+4
| | | | | | | | | | | prio_bias should only be adjusted in set_user_nice if p is actually currently queued. Signed-off-by: Con Kolivas <kernel@kolivas.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: implement nice support across physical cpus on SMPCon Kolivas2005-11-091-18/+83
| | | | | | | | | | | | | | | | | | | | 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 <kernel@kolivas.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] unexport idle_cpuAdrian Bunk2005-11-071-2/+0
| | | | | | | | | I didn't find any possible modular usage in the kernel. Signed-off-by: Adrian Bunk <bunk@stusta.de> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] cpu hoptlug: avoid usage of smp_processor_id() in preemptible codeHeiko Carstens2005-11-071-1/+2
| | | | | | | | | | | | | | | | | | | | Replace smp_processor_id() with any_online_cpu(cpu_online_map) in order to avoid lots of "BUG: using smp_processor_id() in preemptible [00000001] code:..." messages in case taking a cpu online fails. All the traces start at the last notifier_call_chain(...) in kernel/cpu.c. Since we hold the cpu_control semaphore it shouldn't be any problem to access cpu_online_map. The reason why cpu_up failed is simply that the cpu that was supposed to be taken online wasn't even there. That is because on s390 we never know when a new cpu comes and therefore cpu_possible_map consists of only ones and doesn't reflect reality. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] improve scheduler fairness a bitOleg Nesterov2005-11-041-1/+1
| | | | | | | | Do not transfer remaining time slice to another cpu on process exit. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: hardcode non-smp set_cpus_allowedPaul Jackson2005-10-311-1/+0
| | | | | | | | | | | | | | Simplify the UP (1 CPU) implementatin of set_cpus_allowed. The one CPU is hardcoded to be cpu 0 - so just test for that bit, and avoid having to pick up the cpu_online_map. Also, unexport cpu_online_map: it was only needed for set_cpus_allowed(). Signed-off-by: Paul Jackson <pj@sgi.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: update_hiwaters just in timeHugh Dickins2005-10-301-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | update_mem_hiwater has attracted various criticisms, in particular from those concerned with mm scalability. Originally it was called whenever rss or total_vm got raised. Then many of those callsites were replaced by a timer tick call from account_system_time. Now Frank van Maarseveen reports that to be found inadequate. How about this? Works for Frank. Replace update_mem_hiwater, a poor combination of two unrelated ops, by macros update_hiwater_rss and update_hiwater_vm. Don't attempt to keep mm->hiwater_rss up to date at timer tick, nor every time we raise rss (usually by 1): those are hot paths. Do the opposite, update only when about to lower rss (usually by many), or just before final accounting in do_exit. Handle mm->hiwater_vm in the same way, though it's much less of an issue. Demand that whoever collects these hiwater statistics do the work of taking the maximum with rss or total_vm. And there has been no collector of these hiwater statistics in the tree. The new convention needs an example, so match Frank's usage by adding a VmPeak line above VmSize to /proc/<pid>/status, and also a VmHWM line above VmRSS (High-Water-Mark or High-Water-Memory). There was a particular anomaly during mremap move, that hiwater_vm might be captured too high. A fleeting such anomaly remains, but it's quickly corrected now, whereas before it would stick. What locking? None: if the app is racy then these statistics will be racy, it's not worth any overhead to make them exact. But whenever it suits, hiwater_vm is updated under exclusive mmap_sem, and hiwater_rss under page_table_lock (for now) or with preemption disabled (later on): without going to any trouble, minimize the time between reading current values and updating, to minimize those occasions when a racing thread bumps a count up and back down in between. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] export cpu_online_mapAndrew Morton2005-10-261-0/+1
| | | | | | | | | | | With CONFIG_SMP=n: *** Warning: "cpu_online_map" [drivers/firmware/dcdbas.ko] undefined! due to set_cpus_allowed(). Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Fix spinlock owner debuggingIngo Molnar2005-09-131-4/+4
| | | | | | | | fix up the runqueue lock owner only if we truly did a context-switch with the runqueue lock held. Impacts ia64, mips, sparc64 and arm. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Mark ia64-specific MCA/INIT scheduler hooks as dangerousLinus Torvalds2005-09-121-26/+44
| | | | | | | | | | | | ..and only enable them for ia64. The functions are only valid when the whole system has been totally stopped and no scheduler activity is ongoing on any CPU, and interrupts are globally disabled. In other words, they aren't useful for anything else. So make sure that nobody can use them by mistake. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] MCA/INIT: scheduler hooksKeith Owens2005-09-111-0/+26
| | | | | | | Scheduler hooks to see/change which process is deemed to be on a cpu. Signed-off-by: Keith Owens <kaos@sgi.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
* [PATCH] sched: allow the load to grow upto its cpu_powerSiddha, Suresh B2005-09-101-2/+7
| | | | | | | | | | | Don't pull tasks from a group if that would cause the group's total load to drop below its total cpu_power (ie. cause the group to start going idle). Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: don't kick ALB in the presence of pinned taskSiddha, Suresh B2005-09-101-1/+14
| | | | | | | | | | | | | | | Jack Steiner brought this issue at my OLS talk. Take a scenario where two tasks are pinned to two HT threads in a physical package. Idle packages in the system will keep kicking migration_thread on the busy package with out any success. We will run into similar scenarios in the presence of CMP/NUMA. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: use cached variable in sys_sched_yield()Renaud Lienhart2005-09-101-1/+1
| | | | | | | | | In sys_sched_yield(), we cache current->array in the "array" variable, thus there's no need to dereference "current" again later. Signed-Off-By: Renaud Lienhart <renaud.lienhart@free.fr> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: HT optimisationNick Piggin2005-09-101-6/+28
| | | | | | | | | | | | | | | | | | If an idle sibling of an HT queue encounters a busy sibling, then make higher level load balancing of the non-idle variety. Performance of multiprocessor HT systems with low numbers of tasks (generally < number of virtual CPUs) can be significantly worse than the exact same workloads when running in non-HT mode. The reason is largely due to poor scheduling behaviour. This patch improves the situation, making the performance gap far less significant on one problematic test case (tbench). Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: less lockingNick Piggin2005-09-101-7/+2
| | | | | | | | | | | | | | | | | | | | During periodic load balancing, don't hold this runqueue's lock while scanning remote runqueues, which can take a non trivial amount of time especially on very large systems. Holding the runqueue lock will only help to stabilise ->nr_running, however this doesn't do much to help because tasks being woken will simply get held up on the runqueue lock, so ->nr_running would not provide a really accurate picture of runqueue load in that case anyway. What's more, ->nr_running (and possibly the cpu_load averages) of remote runqueues won't be stable anyway, so load balancing is always an inexact operation. Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: less newidle lockingNick Piggin2005-09-101-7/+10
| | | | | | | | | | | | Similarly to the earlier change in load_balance, only lock the runqueue in load_balance_newidle if the busiest queue found has a nr_running > 1. This will reduce frequency of expensive remote runqueue lock aquisitions in the schedule() path on some workloads. Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: fix SMT scheduler latency bugIngo Molnar2005-09-101-4/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | William Weston reported unusually high scheduling latencies on his x86 HT box, on the -RT kernel. I managed to reproduce it on my HT box and the latency tracer shows the incident in action: _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / du-2803 3Dnh2 0us : __trace_start_sched_wakeup (try_to_wake_up) .............................................................. ... we are running on CPU#3, PID 2778 gets woken to CPU#1: ... .............................................................. du-2803 3Dnh2 0us : __trace_start_sched_wakeup <<...>-2778> (73 1) du-2803 3Dnh2 0us : _raw_spin_unlock (try_to_wake_up) ................................................ ... still on CPU#3, we send an IPI to CPU#1: ... ................................................ du-2803 3Dnh1 0us : resched_task (try_to_wake_up) du-2803 3Dnh1 1us : smp_send_reschedule (try_to_wake_up) du-2803 3Dnh1 1us : send_IPI_mask_bitmask (smp_send_reschedule) du-2803 3Dnh1 2us : _raw_spin_unlock_irqrestore (try_to_wake_up) ............................................... ... 1 usec later, the IPI arrives on CPU#1: ... ............................................... <idle>-0 1Dnh. 2us : smp_reschedule_interrupt (c0100c5a 0 0) So far so good, this is the normal wakeup/preemption mechanism. But here comes the scheduler anomaly on CPU#1: <idle>-0 1Dnh. 2us : preempt_schedule_irq (need_resched) <idle>-0 1Dnh. 2us : preempt_schedule_irq (need_resched) <idle>-0 1Dnh. 3us : __schedule (preempt_schedule_irq) <idle>-0 1Dnh. 3us : profile_hit (__schedule) <idle>-0 1Dnh1 3us : sched_clock (__schedule) <idle>-0 1Dnh1 4us : _raw_spin_lock_irq (__schedule) <idle>-0 1Dnh1 4us : _raw_spin_lock_irqsave (__schedule) <idle>-0 1Dnh2 5us : _raw_spin_unlock (__schedule) <idle>-0 1Dnh1 5us : preempt_schedule (__schedule) <idle>-0 1Dnh1 6us : _raw_spin_lock (__schedule) <idle>-0 1Dnh2 6us : find_next_bit (__schedule) <idle>-0 1Dnh2 6us : _raw_spin_lock (__schedule) <idle>-0 1Dnh3 7us : find_next_bit (__schedule) <idle>-0 1Dnh3 7us : find_next_bit (__schedule) <idle>-0 1Dnh3 8us : _raw_spin_unlock (__schedule) <idle>-0 1Dnh2 8us : preempt_schedule (__schedule) <idle>-0 1Dnh2 8us : find_next_bit (__schedule) <idle>-0 1Dnh2 9us : trace_stop_sched_switched (__schedule) <idle>-0 1Dnh2 9us : _raw_spin_lock (trace_stop_sched_switched) <idle>-0 1Dnh3 10us : trace_stop_sched_switched <<...>-2778> (73 8c) <idle>-0 1Dnh3 10us : _raw_spin_unlock (trace_stop_sched_switched) <idle>-0 1Dnh1 10us : _raw_spin_unlock (__schedule) <idle>-0 1Dnh. 11us : local_irq_enable_noresched (preempt_schedule_irq) <idle>-0 1Dnh. 11us < (0) we didnt pick up pid 2778! It only gets scheduled much later: <...>-2778 1Dnh2 412us : __switch_to (__schedule) <...>-2778 1Dnh2 413us : __schedule <<idle>-0> (8c 73) <...>-2778 1Dnh2 413us : _raw_spin_unlock (__schedule) <...>-2778 1Dnh1 413us : trace_stop_sched_switched (__schedule) <...>-2778 1Dnh1 414us : _raw_spin_lock (trace_stop_sched_switched) <...>-2778 1Dnh2 414us : trace_stop_sched_switched <<...>-2778> (73 1) <...>-2778 1Dnh2 414us : _raw_spin_unlock (trace_stop_sched_switched) <...>-2778 1Dnh1 415us : trace_stop_sched_switched (__schedule) the reason for this anomaly is the following code in dependent_sleeper(): /* * If a user task with lower static priority than the * running task on the SMT sibling is trying to schedule, * delay it till there is proportionately less timeslice * left of the sibling task to prevent a lower priority * task from using an unfair proportion of the * physical cpu's resources. -ck */ [...] if (((smt_curr->time_slice * (100 - sd->per_cpu_gain) / 100) > task_timeslice(p))) ret = 1; Note that in contrast to the comment above, we dont actually do the check based on static priority, we do the check based on timeslices. But timeslices go up and down, and even highprio tasks can randomly have very low timeslices (just before their next refill) and can thus be judged as 'lowprio' by the above piece of code. This condition is clearly buggy. The correct test is to check for static_prio _and_ to check for the preemption priority. Even on different static priority levels, a higher-prio interactive task should not be delayed due to a higher-static-prio CPU hog. There is a symmetric bug in the 'kick SMT sibling' code of this function as well, which can be solved in a similar way. The patch below (against the current scheduler queue in -mm) fixes both bugs. I have build and boot-tested this on x86 SMT, and nice +20 tasks still get properly throttled - so the dependent-sleeper logic is still in action. btw., these bugs pessimised the SMT scheduler because the 'delay wakeup' property was applied too liberally, so this fix is likely a throughput improvement as well. I separated out a smt_slice() function to make the code easier to read. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: TASK_NONINTERACTIVEIngo Molnar2005-09-101-1/+10
| | | | | | | | | | | | | This patch implements a task state bit (TASK_NONINTERACTIVE), which can be used by blocking points to mark the task's wait as "non-interactive". This does not mean the task will be considered a CPU-hog - the wait will simply not have an effect on the waiting task's priority - positive or negative alike. Right now only pipe_wait() will make use of it, because it's a common source of not-so-interactive waits (kernel compilation jobs, etc.). Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched cleanupsIngo Molnar2005-09-101-19/+25
| | | | | | | whitespace cleanups. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: make idlest_group/cpu cpus_allowed-awareM.Baris Demiray2005-09-101-4/+13
| | | | | | | | | | | Add relevant checks into find_idlest_group() and find_idlest_cpu() to make them return only the groups that have allowed CPUs and allowed CPUs respectively. Signed-off-by: M.Baris Demiray <baris@labristeknoloji.com> Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] sched: run SCHED_NORMAL tasks with real time tasks on SMT siblingsCon Kolivas2005-09-101-18/+47
| | | | | | | | | | | | | | | | | | | | | The hyperthread aware nice handling currently puts to sleep any non real time task when a real time task is running on its sibling cpu. This can lead to prolonged starvation by having the non real time task pegged to the cpu with load balancing not pulling that task away. Currently we force lower priority hyperthread tasks to run a percentage of time difference based on timeslice differences which is meaningless when comparing real time tasks to SCHED_NORMAL tasks. We can allow non real time tasks to run with real time tasks on the sibling up to per_cpu_gain% if we use jiffies as a counter. Cleanups and micro-optimisations to the relevant code section should make it more understandable as well. Signed-off-by: Con Kolivas <kernel@kolivas.org> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] spinlock consolidationIngo Molnar2005-09-101-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch (written by me and also containing many suggestions of Arjan van de Ven) does a major cleanup of the spinlock code. It does the following things: - consolidates and enhances the spinlock/rwlock debugging code - simplifies the asm/spinlock.h files - encapsulates the raw spinlock type and moves generic spinlock features (such as ->break_lock) into the generic code. - cleans up the spinlock code hierarchy to get rid of the spaghetti. Most notably there's now only a single variant of the debugging code, located in lib/spinlock_debug.c. (previously we had one SMP debugging variant per architecture, plus a separate generic one for UP builds) Also, i've enhanced the rwlock debugging facility, it will now track write-owners. There is new spinlock-owner/CPU-tracking on SMP builds too. All locks have lockup detection now, which will work for both soft and hard spin/rwlock lockups. The arch-level include files now only contain the minimally necessary subset of the spinlock code - all the rest that can be generalized now lives in the generic headers: include/asm-i386/spinlock_types.h | 16 include/asm-x86_64/spinlock_types.h | 16 I have also split up the various spinlock variants into separate files, making it easier to see which does what. The new layout is: SMP | UP ----------------------------|----------------------------------- asm/spinlock_types_smp.h | linux/spinlock_types_up.h linux/spinlock_types.h | linux/spinlock_types.h asm/spinlock_smp.h | linux/spinlock_up.h linux/spinlock_api_smp.h | linux/spinlock_api_up.h linux/spinlock.h | linux/spinlock.h /* * here's the role of the various spinlock/rwlock related include files: * * on SMP builds: * * asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the * initializers * * linux/spinlock_types.h: * defines the generic type and initializers * * asm/spinlock.h: contains the __raw_spin_*()/etc. lowlevel * implementations, mostly inline assembly code * * (also included on UP-debug builds:) * * linux/spinlock_api_smp.h: * contains the prototypes for the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. * * on UP builds: * * linux/spinlock_type_up.h: * contains the generic, simplified UP spinlock type. * (which is an empty structure on non-debug builds) * * linux/spinlock_types.h: * defines the generic type and initializers * * linux/spinlock_up.h: * contains the __raw_spin_*()/etc. version of UP * builds. (which are NOPs on non-debug, non-preempt * builds) * * (included on UP-non-debug builds:) * * linux/spinlock_api_up.h: * builds the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. */ All SMP and UP architectures are converted by this patch. arm, i386, ia64, ppc, ppc64, s390/s390x, x64 was build-tested via crosscompilers. m32r, mips, sh, sparc, have not been tested yet, but should be mostly fine. From: Grant Grundler <grundler@parisc-linux.org> Booted and lightly tested on a500-44 (64-bit, SMP kernel, dual CPU). Builds 32-bit SMP kernel (not booted or tested). I did not try to build non-SMP kernels. That should be trivial to fix up later if necessary. I converted bit ops atomic_hash lock to raw_spinlock_t. Doing so avoids some ugly nesting of linux/*.h and asm/*.h files. Those particular locks are well tested and contained entirely inside arch specific code. I do NOT expect any new issues to arise with them. If someone does ever need to use debug/metrics with them, then they will need to unravel this hairball between spinlocks, atomic ops, and bit ops that exist only because parisc has exactly one atomic instruction: LDCW (load and clear word). From: "Luck, Tony" <tony.luck@intel.com> ia64 fix Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjanv@infradead.org> Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Cc: Matthew Wilcox <willy@debian.org> Signed-off-by: Hirokazu Takata <takata@linux-m32r.org> Signed-off-by: Mikael Pettersson <mikpe@csd.uu.se> Signed-off-by: Benoit Boissinot <benoit.boissinot@ens-lyon.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Prefetch kernel stacks to speed up context switchChen, Kenneth W2005-09-091-0/+1
| | | | | | | | | | | | | | | For architecture like ia64, the switch stack structure is fairly large (currently 528 bytes). For context switch intensive application, we found that significant amount of cache misses occurs in switch_to() function. The following patch adds a hook in the schedule() function to prefetch switch stack structure as soon as 'next' task is determined. This allows maximum overlap in prefetch cache lines for that structure. Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Merge branch 'upstream' of ↵Linus Torvalds2005-09-081-0/+1
|\ | | | | | | master.kernel.org:/pub/scm/linux/kernel/git/jgarzik/misc-2.6
| * [kernel-doc] fix various DocBook build problems/warningsJeff Garzik2005-09-071-0/+1
| | | | | | | | | | | | | | Most serious is fixing include/sound/pcm.h, which breaks the DocBook build. The other stuff is just filling in things that cause warnings.
* | [PATCH] cpusets: fix the "dynamic sched domains" bugJohn Hawkes2005-09-081-20/+69
| | | | | | | | | | | | | | | | | | | | | | For a NUMA system with multiple CPUs per node, declaring a cpu-exclusive cpuset that includes only some, but not all, of the CPUs in a node will mangle the sched domain structures. Signed-off-by: John Hawkes <hawkes@sgi.com> Cc; Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* | [PATCH] cpusets: Move the ia64 domain setup code to the generic codeJohn Hawkes2005-09-081-54/+236
|/ | | | | | | Signed-off-by: John Hawkes <hawkes@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Make RLIMIT_NICE ranges consistent with getpriority(2)Matt Mackall2005-08-181-2/+2
| | | | | | | | | | | As suggested by Michael Kerrisk <mtk-manpages@gmx.net>, make RLIMIT_NICE consistent with getpriority before it becomes available in released glibc. Signed-off-by: Matt Mackall <mpm@selenic.com> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Chris Wright <chrisw@osdl.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] fix MAX_USER_RT_PRIO and MAX_RT_PRIOSteven Rostedt2005-07-271-2/+3
| | | | | | | | | | | | | Here's the patch again to fix the code to handle if the values between MAX_USER_RT_PRIO and MAX_RT_PRIO are different. Without this patch, an SMP system will crash if the values are different. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Dean Nelson <dcn@sgi.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Fix RLIMIT_RTPRIO breakageAndreas Steinmetz2005-07-271-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | RLIMIT_RTPRIO is supposed to grant non privileged users the right to use SCHED_FIFO/SCHED_RR scheduling policies with priorites bounded by the RLIMIT_RTPRIO value via sched_setscheduler(). This is usually used by audio users. Unfortunately this is broken in 2.6.13rc3 as you can see in the excerpt from sched_setscheduler below: /* * Allow unprivileged RT tasks to decrease priority: */ if (!capable(CAP_SYS_NICE)) { /* can't change policy */ if (policy != p->policy) return -EPERM; After the above unconditional test which causes sched_setscheduler to fail with no regard to the RLIMIT_RTPRIO value the following check is made: /* can't increase priority */ if (policy != SCHED_NORMAL && param->sched_priority > p->rt_priority && param->sched_priority > p->signal->rlim[RLIMIT_RTPRIO].rlim_cur) return -EPERM; Thus I do believe that the RLIMIT_RTPRIO value must be taken into account for the policy check, especially as the RLIMIT_RTPRIO limit is of no use without this change. The attached patch fixes this problem. Signed-off-by: Andreas Steinmetz <ast@domdv.de> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] cond_resched(): fix bogus might_sleep() warningIngo Molnar2005-07-081-0/+7
| | | | | | | | | | The BKS might be reacquired before we have dropped PREEMPT_ACTIVE, which could trigger a second could trigger a second cond_resched() call. Bug found by Hirofumi Ogawa. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Tweak idle thread setup semanticsIngo Molnar2005-06-281-1/+8
| | | | | | | | | | | | | | This patch tweaks idle thread setup semantics a bit: instead of setting NEED_RESCHED in init_idle(), we do an explicit schedule() before calling into cpu_idle(). This patch, while having no negative side-effects, enables wider use of cond_resched()s. (which might happen in the stock kernel too, but it's particulary important for voluntary-preempt) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Update cfq io scheduler to time sliced designJens Axboe2005-06-271-8/+0
| | | | | | | | | | | | | | This updates the CFQ io scheduler to the new time sliced design (cfq v3). It provides full process fairness, while giving excellent aggregate system throughput even for many competing processes. It supports io priorities, either inherited from the cpu nice value or set directly with the ioprio_get/set syscalls. The latter closely mimic set/getpriority. This import is based on my latest from -mm. Signed-off-by: Jens Axboe <axboe@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Merge Christoph's freeze cleanup patchLinus Torvalds2005-06-261-2/+1
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| * [PATCH] Cleanup patch for process freezingChristoph Lameter2005-06-261-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 1. Establish a simple API for process freezing defined in linux/include/sched.h: frozen(process) Check for frozen process freezing(process) Check if a process is being frozen freeze(process) Tell a process to freeze (go to refrigerator) thaw_process(process) Restart process frozen_process(process) Process is frozen now 2. Remove all references to PF_FREEZE and PF_FROZEN from all kernel sources except sched.h 3. Fix numerous locations where try_to_freeze is manually done by a driver 4. Remove the argument that is no longer necessary from two function calls. 5. Some whitespace cleanup 6. Clear potential race in refrigerator (provides an open window of PF_FREEZE cleared before setting PF_FROZEN, recalc_sigpending does not check PF_FROZEN). This patch does not address the problem of freeze_processes() violating the rule that a task may only modify its own flags by setting PF_FREEZE. This is not clean in an SMP environment. freeze(process) is therefore not SMP safe! Signed-off-by: Christoph Lameter <christoph@lameter.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* | [PATCH] Dynamic sched domains: sched changesDinakar Guniguntala2005-06-261-46/+86
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The following patches add dynamic sched domains functionality that was extensively discussed on lkml and lse-tech. I would like to see this added to -mm o The main advantage with this feature is that it ensures that the scheduler load balacing code only balances against the cpus that are in the sched domain as defined by an exclusive cpuset and not all of the cpus in the system. This removes any overhead due to load balancing code trying to pull tasks outside of the cpu exclusive cpuset only to be prevented by the tasks' cpus_allowed mask. o cpu exclusive cpusets are useful for servers running orthogonal workloads such as RT applications requiring low latency and HPC applications that are throughput sensitive o It provides a new API partition_sched_domains in sched.c that makes dynamic sched domains possible. o cpu_exclusive cpusets sets are now associated with a sched domain. Which means that the users can dynamically modify the sched domains through the cpuset file system interface o ia64 sched domain code has been updated to support this feature as well o Currently, this does not support hotplug. (However some of my tests indicate hotplug+preempt is currently broken) o I have tested it extensively on x86. o This should have very minimal impact on performance as none of the fast paths are affected Signed-off-by: Dinakar Guniguntala <dino@in.ibm.com> Acked-by: Paul Jackson <pj@sgi.com> Acked-by: Nick Piggin <nickpiggin@yahoo.com.au> Acked-by: Matthew Dobson <colpatch@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* | [PATCH] Changing RT priority without CAP_SYS_NICEOlivier Croquette2005-06-261-7/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Presently, a process without the capability CAP_SYS_NICE can not change its own policy, which is OK. But it can also not decrease its RT priority (if scheduled with policy SCHED_RR or SCHED_FIFO), which is what this patch changes. The rationale is the same as for the nice value: a process should be able to require less priority for itself. Increasing the priority is still not allowed. This is for example useful if you give a multithreaded user process a RT priority, and the process would like to organize its internal threads using priorities also. Then you can give the process the highest priority needed N, and the process starts its threads with lower priorities: N-1, N-2... The POSIX norm says that the permissions are implementation specific, so I think we can do that. In a sense, it makes the permissions consistent whatever the policy is: with this patch, process scheduled by SCHED_FIFO, SCHED_RR and SCHED_OTHER can all decrease their priority. From: Ingo Molnar <mingo@elte.hu> cleaned up and merged to -mm. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* | [PATCH] sched: micro-optimize task requeueing in schedule()Chen Shang2005-06-261-7/+12
| | | | | | | | | | | | | | | | micro-optimize task requeueing in schedule() & clean up recalc_task_prio(). Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* | [PATCH] sched: relax pinned balancingNick Piggin2005-06-261-2/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The maximum rebalance interval allowed by the multiprocessor balancing backoff is often not large enough to handle corner cases where there are lots of tasks pinned on a CPU. Suresh reported: I see system livelock's if for example I have 7000 processes pinned onto one cpu (this is on the fastest 8-way system I have access to). After this patch, the machine is reported to go well above this number. Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* | [PATCH] sched: consolidate sbe sbfNick Piggin2005-06-261-106/+68
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Consolidate balance-on-exec with balance-on-fork. This is made easy by the sched-domains RCU patches. As well as the general goodness of code reduction, this allows the runqueues to be unlocked during balance-on-fork. schedstats is a problem. Maybe just have balance-on-event instead of distinguishing fork and exec? Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* | [PATCH] sched: RCU domainsNick Piggin2005-06-261-45/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | One of the problems with the multilevel balance-on-fork/exec is that it needs to jump through hoops to satisfy sched-domain's locking semantics (that is, you may traverse your own domain when not preemptable, and you may traverse others' domains when holding their runqueue lock). balance-on-exec had to potentially migrate between more than one CPU before finding a final CPU to migrate to, and balance-on-fork needed to potentially take multiple runqueue locks. So bite the bullet and make sched-domains go completely RCU. This actually simplifies the code quite a bit. From: Ingo Molnar <mingo@elte.hu> schedstats RCU fix, and a nice comment on for_each_domain, from Ingo. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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