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- 18 Aug, 2005 1 commit
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Matt Mackall authored
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>
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- 26 Jul, 2005 2 commits
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Steven Rostedt authored
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:
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Andreas Steinmetz authored
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:
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- 08 Jul, 2005 1 commit
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Ingo Molnar authored
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:
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- 28 Jun, 2005 1 commit
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Ingo Molnar authored
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:
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- 27 Jun, 2005 1 commit
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Jens Axboe authored
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:
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- 26 Jun, 2005 1 commit
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Christoph Lameter authored
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:
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- 25 Jun, 2005 22 commits
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Dinakar Guniguntala authored
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:
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Olivier Croquette authored
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:
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Chen Shang authored
micro-optimize task requeueing in schedule() & clean up recalc_task_prio(). Signed-off-by:
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Nick Piggin authored
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:
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Nick Piggin authored
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:
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Nick Piggin authored
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:
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Nick Piggin authored
The fundamental problem that Suresh has with balance on exec and fork is that it only tries to balance the top level domain with the flag set. This was worked around by removing degenerate domains, but is still a problem if people want to start using more complex sched-domains, especially multilevel NUMA that ia64 is already using. This patch makes balance on fork and exec try balancing over not just the top most domain with the flag set, but all the way down the domain tree. Signed-off-by:
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Suresh Siddha authored
Remove degenerate scheduler domains during the sched-domain init. For example on x86_64, we always have NUMA configured in. On Intel EM64T systems, top most sched domain will be of NUMA and with only one sched_group in it. With fork/exec balances(recent Nick's fixes in -mm tree), we always endup taking wrong decisions because of this topmost domain (as it contains only one group and find_idlest_group always returns NULL). We will endup loading HT package completely first, letting active load balance kickin and correct it. In general, this patch also makes sense with out recent Nick's fixes in -mm. From: Nick Piggin <nickpiggin@yahoo.com.au> Modified to account for more than just sched_groups when scanning for degenerate domains by Nick Piggin. And allow a runqueue's sd to go NULL rather than keep a single degenerate domain around (this happens when you run with maxcpus=1). Signed-off-by:
Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by:
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Nick Piggin authored
Fix the last 2 places that directly access a runqueue's sched-domain and assume it cannot be NULL. That allows the use of NULL for domain, instead of a dummy domain, to signify no balancing is to happen. No functional changes. Signed-off-by:
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Nick Piggin authored
Instead of requiring architecture code to interact with the scheduler's locking implementation, provide a couple of defines that can be used by the architecture to request runqueue unlocked context switches, and ask for interrupts to be enabled over the context switch. Also replaces the "switch_lock" used by these architectures with an oncpu flag (note, not a potentially slow bitflag). This eliminates one bus locked memory operation when context switching, and simplifies the task_running function. Signed-off-by:
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Ingo Molnar authored
"Chen, Kenneth W" <kenneth.w.chen@intel.com> uninline task_timeslice() - reduces code footprint noticeably, and it's slowpath code. Signed-off-by:
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Nick Piggin authored
Add SCHEDSTAT statistics for sched-balance-fork. Signed-off-by:
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Nick Piggin authored
Reimplement the balance on exec balancing to be sched-domains aware. Use this to also do balance on fork balancing. Make x86_64 do balance on fork over the NUMA domain. The problem that the non sched domains aware blancing became apparent on dual core, multi socket opterons. What we want is for the new tasks to be sent to a different socket, but more often than not, we would first load up our sibling core, or fill two cores of a single remote socket before selecting a new one. This gives large improvements to STREAM on such systems. Signed-off-by:
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Nick Piggin authored
Remove the very aggressive idle stuff that has recently gone into 2.6 - it is going against the direction we are trying to go. Hopefully we can regain performance through other methods. Signed-off-by:
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Nick Piggin authored
Do less affine wakeups. We're trying to reduce dbt2-pgsql idle time regressions here... make sure we don't don't move tasks the wrong way in an imbalance condition. Also, remove the cache coldness requirement from the calculation - this seems to induce sharp cutoff points where behaviour will suddenly change on some workloads if the load creeps slightly over or under some point. It is good for periodic balancing because in that case have otherwise have no other context to determine what task to move. But also make a minor tweak to "wake balancing" - the imbalance tolerance is now set at half the domain's imbalance, so we get the opportunity to do wake balancing before the more random periodic rebalancing gets preformed. Signed-off-by:
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Nick Piggin authored
Do CPU load averaging over a number of different intervals. Allow each interval to be chosen by sending a parameter to source_load and target_load. 0 is instantaneous, idx > 0 returns a decaying average with the most recent sample weighted at 2^(idx-1). To a maximum of 3 (could be easily increased). So generally a higher number will result in more conservative balancing. Signed-off-by:
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Nick Piggin authored
Remove the special casing for idle CPU balancing. Things like this are hurting for example on SMT, where are single sibling being idle doesn't really warrant a really aggressive pull over the NUMA domain, for example. Signed-off-by:
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Nick Piggin authored
These conditions should now be impossible, and we need to fix them if they happen. Signed-off-by:
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Nick Piggin authored
SMT balancing has a couple of problems. Firstly, active_load_balance is too complex - basically it should be a dumb helper for when the periodic balancer has determined there is an imbalance, but gets stuck because the task is running. So rip out all its "smarts", and just make it move one task to the target CPU. Second, the busy CPU's sched-domain tree was being used for active balancing. This means that it may not see that nr_balance_failed has reached a critical level. So use the target CPU's sched-domain tree for this. We can do this because we hold its runqueue lock. Lastly, reset nr_balance_failed to a point where we allow cache hot migration. This will help ensure active load balancing is successful. Thanks to Suresh Siddha for pointing out these issues. Signed-off-by:
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Nick Piggin authored
Fix up active load balancing a bit so it doesn't get called when it shouldn't. Reset the nr_balance_failed counter at more points where we have found conditions to be balanced. This reduces too aggressive active balancing seen on some workloads. Signed-off-by:
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Nick Piggin authored
John Hawkes explained the problem best: A large number of processes that are pinned to a single CPU results in every other CPU's load_balance() seeing this overloaded CPU as "busiest", yet move_tasks() never finds a task to pull-migrate. This condition occurs during module unload, but can also occur as a denial-of-service using sys_sched_setaffinity(). Several hundred CPUs performing this fruitless load_balance() will livelock on the busiest CPU's runqueue lock. A smaller number of CPUs will livelock if the pinned task count gets high. Expanding slightly on John's patch, this one attempts to work out whether the balancing failure has been due to too many tasks pinned on the runqueue. This allows it to be basically invisible to the regular blancing paths (ie. when there are no pinned tasks). We can use this extra knowledge to shut down the balancing faster, and ensure the migration threads don't start running which is another problem observed in the wild. Signed-off-by:
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Nick Piggin authored
New sched-domains code means we don't get spans with offline CPUs in them. Signed-off-by:
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- 23 Jun, 2005 2 commits
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Benjamin LaHaise authored
In the upcoming aio_down patch, it is useful to store a private data pointer in the kiocb's wait_queue. Since we provide our own wake up function and do not require the task_struct pointer, it makes sense to convert the task pointer into a generic private pointer. Signed-off-by:
Benjamin LaHaise <benjamin.c.lahaise@intel.com> Signed-off-by:
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Jesper Juhl authored
In kernel/sched.c the return value from preempt_count() is cast to an int. That made sense when preempt_count was defined as different types on is not needed and should go away. The patch removes the cast. In kernel/timer.c the return value from preempt_count() is assigned to a variable of type u32 and then that unsigned value is later compared to preempt_count(). Since preempt_count() returns an int, an int is what should be used to store its return value. Storing the result in an unsigned 32bit integer made a tiny bit of sense back when preempt_count was different types on different archs, but no more - let's not play signed vs unsigned comparison games when we don't have to. The patch modifies the code to use an int to hold the value. While I was around that bit of code I also made two changes to a nearby (related) printk() - I modified it to specify the loglevel explicitly and also broke the line into a few pieces to avoid it being longer than 80 chars and clarified the text a bit. Signed-off-by:
Jesper Juhl <juhl-lkml@dif.dk> Signed-off-by:
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- 22 Jun, 2005 1 commit
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Ingo Molnar authored
This patch implements a number of smp_processor_id() cleanup ideas that Arjan van de Ven and I came up with. The previous __smp_processor_id/_smp_processor_id/smp_processor_id API spaghetti was hard to follow both on the implementational and on the usage side. Some of the complexity arose from picking wrong names, some of the complexity comes from the fact that not all architectures defined __smp_processor_id. In the new code, there are two externally visible symbols: - smp_processor_id(): debug variant. - raw_smp_processor_id(): nondebug variant. Replaces all existing uses of _smp_processor_id() and __smp_processor_id(). Defined by every SMP architecture in include/asm-*/smp.h. There is one new internal symbol, dependent on DEBUG_PREEMPT: - debug_smp_processor_id(): internal debug variant, mapped to smp_processor_id(). Also, i moved debug_smp_processor_id() from lib/kernel_lock.c into a new lib/smp_processor_id.c file. All related comments got updated and/or clarified. I have build/boot tested the following 8 .config combinations on x86: {SMP,UP} x {PREEMPT,!PREEMPT} x {DEBUG_PREEMPT,!DEBUG_PREEMPT} I have also build/boot tested x64 on UP/PREEMPT/DEBUG_PREEMPT. (Other architectures are untested, but should work just fine.) Signed-off-by:Arjan van de Ven <arjan@infradead.org> Signed-off-by:
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- 14 Jun, 2005 1 commit
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Jan Kara authored
On one path, cond_resched_lock() fails to return true if it dropped the lock. We think this might be causing the crashes in JBD's log_do_checkpoint(). Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by:
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- 20 May, 2005 1 commit
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Paul Jackson authored
This patch removes the entwining of cpusets and hotplug code in the "No more Mr. Nice Guy" case of sched.c move_task_off_dead_cpu(). Since the hotplug code is holding a spinlock at this point, we cannot take the cpuset semaphore, cpuset_sem, as would seem to be required either to update the tasks cpuset, or to scan up the nested cpuset chain, looking for the nearest cpuset ancestor that still has some CPUs that are online. So we just punt and blast the tasks cpus_allowed with all bits allowed. This reverts these lines of code to what they were before the cpuset patch. And it updates the cpuset Doc file, to match. The one known alternative to this that seems to work came from Dinakar Guniguntala, and required the hotplug code to take the cpuset_sem semaphore much earlier in its processing. So far as we know, the increased locking entanglement between cpusets and hot plug of this alternative approach is not worth doing in this case. Signed-off-by:
Nathan Lynch <ntl@pobox.com> Acked-by:
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- 01 May, 2005 2 commits
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Martin Waitz authored
Some KernelDoc descriptions are updated to match the current code. No code changes. Signed-off-by:
Martin Waitz <tali@admingilde.org> Signed-off-by:
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Matt Mackall authored
Add a pair of rlimits for allowing non-root tasks to raise nice and rt priorities. Defaults to traditional behavior. Originally written by Chris Wright. The patch implements a simple rlimit ceiling for the RT (and nice) priorities a task can set. The rlimit defaults to 0, meaning no change in behavior by default. A value of 50 means RT priority levels 1-50 are allowed. A value of 100 means all 99 privilege levels from 1 to 99 are allowed. CAP_SYS_NICE is blanket permission. (akpm: see http://www.uwsg.iu.edu/hypermail/linux/kernel/0503.1/1921.html for tips on integrating this with PAM). Signed-off-by:
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- 18 Apr, 2005 1 commit
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Ingo Molnar authored
Signed-off-by:
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- 16 Apr, 2005 1 commit
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Linus Torvalds authored
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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