| Commit message (Collapse) | Author | Age |
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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').
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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.
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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>
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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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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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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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Large sched_trace buffers cause boot problems on the ARM box. Allow
the user to specify smaller buffers.
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If no events are defined but Feater-Trace support is enabled, then the current
implementation generates a link error because the __event_table sections is
absent.
> arch/x86/built-in.o: In function `ft_disable_all_events':
> (.text+0x242af): undefined reference to `__start___event_table'
As a simple work around, we force zero-element array to always be "allocated"
in the __event_table section. This ensures that we end up with a zero-byte
section if no events are enabled, and does not affect the layout of the section
if events are present.
> bbb@ludwig:~/dev/litmus2010$ nm vmlinux | grep event_table
> ffffffff81950cdc D __event_table_dummy
> ffffffff81950cdc A __start___event_table
> ffffffff81950cdc A __stop___event_table
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Feather-Trace rewrites instructions in the kernel's .text segment.
This segment may be write-protected if CONFIG_DEBUG_RODATA is selected.
In this case, fall back to the default flag-based Feather-Trace
implementation. In the future, we could either adopt the ftrace method
of rewriting .text addresses using non-.text mappings or we could
consider replacing Feather-Trace with ftrace altogether.
For now, this patch avoids unexpected runtime errors.
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The PFAIR plugin always implicitly assumed !NO_HZ (the schedule
is wrong if NO_HZ is enabled) and does not built if hrtimers are absent:
> litmus/built-in.o: In function `pfair_activate_plugin':
> sched_pfair.c:(.text+0x7f07): undefined reference to `cpu_stagger_offset'
> litmus/built-in.o: In function `init_pfair':
> sched_pfair.c:(.init.text+0x487): undefined reference to `cpu_stagger_offset'
cpu_stagger_offset() is only available if hrtimers are enabled.
This patch makes these dependencies explicit.
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C-EDF depends on intel_cacheinfo.c (for get_shared_cpu_map()) which is
only available on x86 architectures. Furthermore, get_shared_cpu_map()
is only available if SYSFS filesystem is present.
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There is currently no need to implement this in ARM.
So let's make it optional instead.
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Introduces CONFIG_RELEASE_MASTER and makes release
master support dependent on the new symbol. This is
useful because dedicated interrupt handling only applies
to "large" multicore platforms. This will allow us to
not implement smp_send_pull_timers() for all platforms.
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C-EDF only makes sense on multicore platforms that have shared caches.
Make it possible to disable it on other platforms, in particular,
on those that do not export get_shared_cpu_map().
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Re-introduce NP sections in the configuration and in litmus.h. Remove the old
np_flag from rt_param.
If CONFIG_NP_SECTION is disabled, then all non-preemptive section checks are
constant expressions which should get removed by the dead code elimination
during optimization.
Instead of re-implementing sys_exit_np(), we simply repurposed sched_yield()
for calling into the scheduler to trigger delayed preemptions.
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Port 2008.3 Core LITMUS^RT infrastructure to Linux 2.6.32
litmus_sched_class implements 4 new methods:
- prio_changed:
void
- switched_to:
void
- get_rr_interval:
return infinity (i.e., 0)
- select_task_rq:
return current cpu
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