litmus-rt.git, branch wip-timer-trace The LITMUS^RT kernel. bugfix: C-EDF, clear scheduled field of the correct CPU upon task_exit 2010-12-25T10:44:29+00:00 Andrea Bastoni bastoni@cs.unc.edu 2010-12-21T23:19:27+00:00 d06b68ec1e82842e02c37977fcebc0626d0becd5 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> 
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>
bugfix: avoid underflow in budget_remaining() 2010-11-29T17:58:09+00:00 Bjoern B. Brandenburg bbb@cs.unc.edu 2010-11-29T14:20:03+00:00 f07bb0a4549916107a7619d0bc4cb5dc09d5744a 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> 
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>
bugfix: fix out-of-bound array access in cedf_activate_plugin() 2010-11-29T17:57:44+00:00 Andrea Bastoni bastoni@cs.unc.edu 2010-11-25T12:29:31+00:00 7b544c16beaa1f6ec70a72d53fe84cae95f70a41 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> 
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>
add optional [function@file:line] tag to TRACE() log 2010-11-22T20:12:40+00:00 Bjoern B. Brandenburg bbb@cs.unc.edu 2010-11-22T06:25:19+00:00 2aad06b056054442964f46752bdb098030cdb866 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 
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() 2010-11-22T20:12:06+00:00 Bjoern B. Brandenburg bbb@cs.unc.edu 2010-11-22T05:39:45+00:00 7779685f05219ff6e713ee6591644c080f51a8bf 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. 
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.
Bugfix: synchronize with all other CPUs before switching plugin 2010-11-20T23:15:14+00:00 Andrea Bastoni bastoni@cs.unc.edu 2010-11-19T11:52:08+00:00 d40413efabc0ab388f6ed83f48b28dc253d47238 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. 
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.
Improve help message for TRACE() buffer 2010-11-16T16:44:54+00:00 Bjoern B. Brandenburg bbb@cs.unc.edu 2010-11-16T16:44:54+00:00 1726017e944d0086f14f867befbf5ebf07adc7dd It's not being allocated per cpu anymore. Further, provide a hint to the user where to find the data in userspace. 
It's not being allocated per cpu anymore. Further, provide a hint to
the user where to find the data in userspace.
Make TRACE() buffer size configurable 2010-11-16T16:22:45+00:00 Bjoern B. Brandenburg bbb@cs.unc.edu 2010-11-16T16:13:10+00:00 d922f5eb1c375ab0445240110656c1d793eaad04 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>. 
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>.
Workaround: do not set rq->skip_clock_update 2010-11-11T23:00:33+00:00 Bjoern B. Brandenburg bbb@cs.unc.edu 2010-11-11T21:54:20+00:00 6fbc3b495cccf2e4ab7d4ab674b5c576e9946bed 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. 
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.
Remove LITMUS^RT TRACE_BUG_ON macro 2010-11-11T23:00:31+00:00 Bjoern B. Brandenburg bbb@cs.unc.edu 2010-11-11T07:54:40+00:00 5a0df8d4e9a5da47c804d89426f06e08aa44426f 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. 
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.