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* EDF priority tie-breaks.wip-robust-tie-breakGlenn Elliott2012-08-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Instead of tie-breaking by PID (which is a static priority tie-break), we can tie-break by other job-level-unique parameters. This is desirable because tasks are equaly affected by tardiness since static priority tie-breaks cause tasks with greater PID values to experience the most tardiness. There are four tie-break methods: 1) Lateness. If two jobs, J_{1,i} and J_{2,j} of tasks T_1 and T_2, respectively, have equal deadlines, we favor the job of the task that had the worst lateness for jobs J_{1,i-1} and J_{2,j-1}. Note: Unlike tardiness, lateness may be less than zero. This occurs when a job finishes before its deadline. 2) Normalized Lateness. The same as #1, except lateness is first normalized by each task's relative deadline. This prevents tasks with short relative deadlines and small execution requirements from always losing tie-breaks. 3) Hash. The job tuple (PID, Job#) is used to generate a hash. Hash values are then compared. A job has ~50% chance of winning a tie-break with respect to another job. Note: Emperical testing shows that some jobs can have +/- ~1.5% advantage in tie-breaks. Linux's built-in hash function is not totally a uniform hash. 4) PIDs. PID-based tie-break used in prior versions of Litmus. Conflicts: litmus/edf_common.c
* New Feature: Arbitrary deadlines.2012.2Glenn Elliott2012-08-01
| | | | | | | | | | | | Added support for arbitrary deadlines. Constraint: Relative deadline must be >= exec cost. Use: Set relative deadline in rt_task::rdeadline. Set value to 0 to default to implicit deadlines. Limitations: PFAIR not supported by this patch. PFAIR updated to reject tasks that do not have implicit deadlines.
* P-FP: Clarify meaning of prioritiesBjoern Brandenburg2012-07-23
| | | | | | Add a comment to explain how priorities are interpreted, and provide some useful macros for userspace.
* P-FP: make PCP available to userspaceSven Dziadek2012-07-23
| | | | Prior to that it was only used internally for DPCP
* P-FP: port P-FP plugin used in B. Brandenburg'sSven Dziadek2012-07-23
| | | | | | | | | | dissertation (branch bbb-diss) to current version of litmus This is needed for ongoing projects I took the unchanged code but removed some leftovers of OMLP which is not implemented
* GSN-EDF: do not requeue jobs without budgetBjoern Brandenburg2012-05-31
| | | | | | | | | | This patch changes how preemptions of jobs without budget work. Instead of requeuing them, they are now only added if they are not subject to budget enforcement or if they have non-zero budget. This allows us to process job completions that race with preemptions. This appears to fix a BUG in budget.c:65 reported by Giovani Gracioli.
* Move budget-related helpers to budget.hBjoern Brandenburg2012-05-31
| | | | | | | | | litmus.h is accumulating too many things. Since we already have budget.h, let's stick all budget-related inline functions there as well. This patch is merely cosmetic; it does not change how budget enforcement works.
* An efficient binary heap implementation.wip-stage-binheapGlenn Elliott2012-05-26
| | | | | | | An efficient binary heap implementation coded in the style of Linux's list. This binary heap should be able to replace any partially sorted priority queue based upon Linux's list.
* Add kernel-style events for sched_trace_XXX() functionsAndrea Bastoni2012-03-30
| | | | | | | | | | | | | | | | | | Enable kernel-style events (tracepoint) for Litmus. Litmus events trace the same functions as the sched_trace_XXX(), but can be enabled independently. So, why another tracing infrastructure then: - Litmus tracepoints can be recorded and analyzed together (single time reference) with all other kernel tracing events (e.g., sched:sched_switch, etc.). It's easier to correlate the effects of kernel events on litmus tasks. - It enables a quick way to visualize and process schedule traces using trace-cmd utility and kernelshark visualizer. Kernelshark lacks unit-trace's schedule-correctness checks, but it enables a fast view of schedule traces and it has several filtering options (for all kernel events, not only Litmus').
* Typo in macroJonathan Herman2012-02-16
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* Feather-Trace: keep track of interrupt-related interference.2012.1Bjoern B. Brandenburg2012-01-30
| | | | | | | Increment a processor-local counter whenever an interrupt is handled. This allows Feather-Trace to include a (truncated) counter and a flag to report interference from interrupts. This could be used to filter samples that were disturbed by interrupts.
* Litmus core: simplify np-section protocolwip-2011.2-bbbBjoern B. Brandenburg2011-11-24
| | | | | | User a 32-bit word for all non-preemptive section flags. Set the "please yield soon" flag atomically when accessing it on remotely-scheduled tasks.
* ftdev: let bufffer-specific code handle writes from userspaceBjoern B. Brandenburg2011-11-24
| | | | | This allows us to splice in information into logs from events that were recorded in userspace.
* Feather-Trace: keep track of release latencyBjoern B. Brandenburg2011-11-24
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* Feather-Trace: trace locking-related suspensionsBjoern B. Brandenburg2011-11-24
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* Add option to turn off preemption state tracingBjoern B. Brandenburg2011-11-24
| | | | | | Preemption state tracing is only useful when debugging preemption- and IPI-related races. Since it creates a lot of clutter in the logs, this patch turns it off unless explicitly requested.
* C-EDF: Make migration affinity work with Release MasterGlenn Elliott2011-08-27
| | | | | | | | | | Needed to update C-EDF to handle release master. Also updated get_nearest_available_cpu() to take NO_CPU instead of -1 to indicate that there is no release master. While NO_CPU is 0xffffffff (-1 in two's complement), we still translate this value to -1 in case NO_CPU changes. Signed-off-by: Andrea Bastoni <bastoni@cs.unc.edu>
* COMMENT: Correct comment on precise budget enforcementGlenn Elliott2011-08-27
| | | | | Original comment said that this feature wasn't supported, though it has been since around October 2010.
* Avoid needlessly costly migrations. CONFIG_SCHED_CPU_AFFINITYGlenn Elliott2011-08-27
| | | | | | | | | | | | | Given a choice between several available CPUs (unlinked) on which to schedule a task, let the scheduler select the CPU closest to where that task was previously scheduled. Hopefully, this will reduce cache migration penalties. Notes: SCHED_CPU_AFFINITY is dependent upon x86 (only x86 is supported at this time). Also PFair/PD^2 does not make use of this feature. Signed-off-by: Andrea Bastoni <bastoni@cs.unc.edu>
* Improve FMLP queue management.wip-fmlp-dequeueGlenn Elliott2011-03-31
| | | | | | | | | | The next owner of a FMLP-protected resource is dequeued from the FMLP FIFO queue by unlock() (when the resource is freed by the previous owner) instead of performing the dequeue by the next owner immediately after it has been woken up. This simplifies the code a little bit and also reduces potential spinlock contention.
* Litmus core: add generic clustering supportBjoern B. Brandenburg2011-02-01
| | | | | Inspired by the existing C-EDF code, this generic version will build clusters of CPUs based on a given cache level.
* Litmus core: extract userspace interface from C-EDFBjoern B. Brandenburg2011-02-01
| | | | | Make the cluster size configuration in C-EDF generic so that it can be used by other clustered schedulers.
* Feather-Trace: rename locking trace pointsBjoern B. Brandenburg2011-02-01
| | | | | Since we don't expect to trace more than one lock type at a time, having protocol-specific trace points is not required.
* fdso: pass userpsace config argument to object constructorBjoern B. Brandenburg2011-02-01
| | | | | | | | | | | | As Glenn pointed out, it is useful for some protocols (e.g., k-exclusion protocols) to know the userspace configuration at object creation time. This patch changes the fdso API to pass the parameter to the object constructor, which is then in turn passed to the lock allocater. The return code from the lock allocater is passed to userspace in return. This also fixes some null pointer dereferences in the FDSO code found by the test suite in liblitmus.
* PSN-EDF: re-implement FMLP supportBjoern B. Brandenburg2011-02-01
| | | | | Implement the partitioned FMLP with priority boosting based on the generic lock API.
* EDF: support priority boostingBjoern B. Brandenburg2011-02-01
| | | | While we are at it, simplify edf_higher_prio() a bit.
* FMLP: remove old implementationBjoern B. Brandenburg2011-02-01
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* SRP: port to new generic locking APIBjoern B. Brandenburg2011-02-01
| | | | | This re-enables SRP support under PSN-EDF and demonstrates how the new locking API should be used.
* Litmus core: replace FMLP & SRP system calls with generic syscallsBjoern B. Brandenburg2011-02-01
| | | | | This renders the FMLP and SRP unfunctional until they are ported to the new locking API.
* Litmus core: add generic locking APIBjoern B. Brandenburg2011-02-01
| | | | | Provide a unified userspace interface for plugin-specific locking protocols.
* Litmus core: change plugin locking interface to generic 'allocate_lock()'Bjoern B. Brandenburg2011-02-01
| | | | | | | | | As the number of supported locking protocols is expected to rise, hard-coding things like priority inheritance in the plugin interface doesn't scale. Instead, use a new generic lock-ops approach. With this approach, each plugin can define its own protocol implementation (or use a generic one), and plugins can support multiple protocols without having to change the plugin interface for each protocol.
* fdso: supply object type to constructor and destructor methodsBjoern B. Brandenburg2011-02-01
| | | | Passing the object type explicitly will enable generic lock constructors.
* Fixed is_hrt, is_srt, and is_be macros.Jonathan Herman2011-02-01
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* Added task class to feather trace param record.Jonathan Herman2011-02-01
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* Litmus core: add copy_and_chomp() helperBjoern B. Brandenburg2011-01-30
| | | | | | We read in a line from userspace and remove the trailing newline in a number of places. This function extracts the common code to avoid future duplication.
* Added support for tracing arbitrary actions.wip-eventsJonathan Herman2011-01-26
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* Feather-Trace: dynamic memory allocation and clean exit2011.1Christopher Kenna2011-01-12
| | | | | | This patch changes Feather-Trace to allocate memory for the minor devices dynamically, which addresses a long-standing FIXME. It also provides clean module exit and error conditions for Feather-Trace.
* Feather-Trace: register devices with sysfsChristopher Kenna2011-01-12
| | | | | | | | | | This patch implements support for Feather-Trace devices to use the sysfs file system and, consequently, udev support. This allows us to allocate major/minor numbers for Feather-Trace devices dynamically, which is desirable because our old static allocations tend to create conflicts on modern distributions and/or when there are many cores.
* bugfix: avoid underflow in budget_remaining()Bjoern B. Brandenburg2010-11-29
| | | | | | | budget_remaining() reports incorrect values due to the operands being switched, which leads to an integer underflow. Reported-by: Chris Kenna <cjk@cs.unc.edu>
* add optional [function@file:line] tag to TRACE() logBjoern B. Brandenburg2010-11-22
| | | | | | | | | | | Add information to each trace message that makes it easier to locate where it came from. It is disabled by default since this adds a lot of clutter. Example: 81281 P1 [gsnedf_schedule@litmus/sched_gsn_edf.c:406]: (rtspin/1483:1) blocks:0 out_of_time:0 np:0 sleep:1 preempt:0 state:0 sig:0 81282 P1 [job_completion@litmus/sched_gsn_edf.c:303]: (rtspin/1483:1) job_completion(). 81283 P1 [__add_release@litmus/rt_domain.c:344]: (rtspin/1483:2) add_release(), rel=41941764351 81284 P1 [gsnedf_schedule@litmus/sched_gsn_edf.c:453]: (rtspin/1483:2) scheduled_on = NO_CPU
* log job number in TRACE_TASK() and TRACE_CUR()Bjoern B. Brandenburg2010-11-22
| | | | | | | | | | | | | | | | For some problems it can be helpful to know which job of a task generated a log message. This patch changes TRACE_TASK to add :<jobno> to the existing (<comm>/<pid>) tag. The result is a trace such as the following, in which the third job of rtspin/1511 completes and the fourth job is added to the release queue. 137615 P0: (rtspin/1511:3) job_completion(). 137616 P0: (rtspin/1511:4) add_release(), rel=262013223089 137617 P0: (rtspin/1511:4) scheduled_on = NO_CPU The job number for non-real-time tasks is always zero.
* Remove LITMUS^RT TRACE_BUG_ON macroBjoern B. Brandenburg2010-11-11
| | | | | | Linux now has a macro of the same name, which causes namespace collisions. Since our version is only being used in two places that haven't triggered in several years, let's just remove it.
* Implement proper remote preemption supportBjoern B. Brandenburg2010-11-11
| | | | | | | | | | | | To date, Litmus has just hooked into the smp_send_reschedule() IPI handler and marked tasks as having to reschedule to implement remote preemptions. This was never particularly clean, but so far we got away with it. However, changes in the underlying Linux, and peculartities of the ARM code (interrupts enabled before context switch) break this naive approach. This patch introduces new state-machine based remote preemption support. By examining the local state before calling set_tsk_need_resched(), we avoid confusing the underlying Linux scheduler. Further, this patch avoids sending unncessary IPIs.
* Split out TRACE() from litmus.h and cleanup some includesBjoern B. Brandenburg2010-11-11
| | | | | | | | | | The TRACE() functionality doesn't need all of litmus.h. Currently, it's impossible to use TRACE() in sched.h due to a circular dependency. This patch moves TRACE() and friends to litmus/sched_debug.h, which can be included in sched.h. While at it, also fix some minor include ugliness that was revealed by this change.
* C-EDF: move /proc/litmus/cluster_cache to /proc/litmus/plugins/C-EDF/clusterBjoern B. Brandenburg2010-11-11
| | | | | | | Make use of the new per-plugin proc file infrastructure to avoid littering the global namespace. While at it, also move all the relevant bits to sched_cedf.c. In the future, each plugin's parameters should be handled in the respective plugin file.
* Litmus core: refactor the implementation of /procChristopher Kenna2010-10-23
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* Litmus core: per-plugin proc directoriesChristopher Kenna2010-10-23
| | | | | | Change the Litmus proc layout so that loaded plugins are visible in /proc/litmus/plugins/loaded and add Litmus functions make_plugin_proc_dir() and remove_plugin_proc_dir() to add per-plugin proc directories.
* Litmus core: add plugin-independent precise budget enforcement infrastructureBjoern B. Brandenburg2010-10-19
| | | | | | | Simple logic: if a task requires precise enforcement, then program a hr-timer to fire when the task must be descheduled. When the timer fires, simply activate the scheduler. When we switch to a different task, either reprogram the timer or cancel it.
* Litmus core: add macro to test for PRECISE_ENFORCEMENTBjoern B. Brandenburg2010-10-19
| | | | | | Required for EDF-WM. We should implement precise enforcement in the core distribution soon anyway (once we know how it works in EDF-WM).
* Litmus core: add budget_remaining() helperBjoern B. Brandenburg2010-10-19
| | | | Quick way to figure out how much budget a LITMUS^RT job has left.
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