| Commit message (Collapse) | Author | Age |
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Otherwise, the release master CPU may try to reschedule in an infinite
loop.
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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.
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Instead of having an extra flag, Pfair should just infer sporadic
release based on deadlines like other plugins, too.
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Just like C-EDF is a global scheduler that is split across several
clusters, Pfair can be applied on a per-cluster basis. This patch
changes the Pfair implementation to enable clustering based on the
recently added generic clustering support.
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Inspired by the existing C-EDF code, this generic version will build
clusters of CPUs based on a given cache level.
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Make the cluster size configuration in C-EDF generic so that it can be
used by other clustered schedulers.
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Since we don't expect to trace more than one lock type at a time,
having protocol-specific trace points is not required.
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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.
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This introduces the global FMLP based on the generic locking layer.
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Implement the partitioned FMLP with priority boosting based on the
generic lock API.
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While we are at it, simplify edf_higher_prio() a bit.
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This re-enables SRP support under PSN-EDF and demonstrates how the new
locking API should be used.
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This renders the FMLP and SRP unfunctional until they are ported to
the new locking API.
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Provide a unified userspace interface for plugin-specific locking
protocols.
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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.
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Passing the object type explicitly will enable generic lock constructors.
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It has always been LITMUS^RT policy that children of real-time tasks
may not skip the admissions test, etc. This used to be enforced, but
was apparently dropped during some port. This commit re-introduces
this policy. This fixes a kernel panic that occurred when "real-time
children" exited without proper initilization.
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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.
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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.
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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.
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Refactor the code that determines the C-EDF cluster size.
- Use an enum with symbolic constants instead of magic int values.
- Complain and fail to switch if an unsupported cluster size is requested.
- Default to ALL as suggested by Glenn and Andrea.
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Do not use the "scheduled_on" field to address the cpus structure
within a cluster. cpus may contain less items than num_online_cpus and
we may cause an out-of-bound access. Instead, use "scheduled_on" to
directly access the per-cpu cpu_entry_t structure.
Reported-by: Jonathan Herman <hermanjl@cs.unc.edu>
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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>
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Make sure to check for maximum index value when accessing cedf_domain_t
array in cedf_activate_plugin().
Reported-by: Jeremy Erickson <jerickso@cs.unc.edu>
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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
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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.
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The CPU triggering the plugin switch should wait until all other CPUs
are in a proper state (synch_on_plugin_switch()) before performing the
actual switch.
Based on the original patch from Jeremy Erickson <jerickso@cs.unc.edu>.
This should solve (for most practical cases) the C-EDF-related
plugin-switch problem reported on the ML.
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It's not being allocated per cpu anymore. Further, provide a hint to
the user where to find the data in userspace.
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Let the user choose an appropriate buffer size (instead of scaling
with NR_CPUS). The kfifo api requires the buffer to be a power of
two, so enforce this constraint in the configuration.
This fixes a previously-existing compile-time error for values of
NR_CPU that are not a power of two.
Based on a patch by Mac Mollison <mollison@cs.unc.edu>.
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Disabling the clock update seems to be causing problems even in normal
Linux, and causes major bugs under LITMUS^RT. As a workaround, just
disable this "optimization" for now.
Details: the idle load balancer causes tasks that suspsend to be
marked with set_tsk_need_resched(). When such a task resumes, it may
wrongly trigger the setting of skip_clock_update. However, a
corresponding rescheduling event may not happen immediately, such that
the currently-scheduled task is no longer charged for its execution
time.
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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.
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The specifier %u doesn't match sizeof() if sizeof() returns a 64bit
quantity on x86_64. Always cast it to int to avoid the warning.
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Since the intial rebased from .24 to .32, the TRACE() implementation
was a hybrid between our old ringbuffer implementation and the new
generic kfifo API. This was a) ugly and b) not save for TRACE()
invoctations during early boot.
This patch rips out the old parts and replaces the actual buffer with a static kfifo.
This also increases TRACE() buffer size considerably. As we avoid a
dynamic allocation, this a larger size is less problematic for debug
builds. This helps a bit with holes in the debug log if the
buffer-flushing task is starved.
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Call into scheduler state machine in the IPI handler.
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Call into scheduler state machine in the IPI handler.
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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.
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Litmus plugins should also be activated if ticks are triggered by
hrtimer.
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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.
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Large sched_trace buffers cause boot problems on the ARM box. Allow
the user to specify smaller buffers.
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Includes the LITMUS^RT-specifc unistd.h extension and modifies the
actual syscall table.
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Make the ARM built aware of the LITMUS^RT-specific options.
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