FULL_PREEMPTION is defined. Add a runtime warning to ULE if PREEMPTION is
enabled (code inspired by the PREEMPTION warning in kern_switch.c). This
is a possible MT5 candidate.
Don't count busy buffers before the initial call to sync() and
don't skip the initial sync() if no busy buffers were called.
Always call sync() at least once if syncing is requested. This
defers the "Syncing disks, buffers remaining..." message until
after the initial sync() call and the first count of busy
buffers. This backs out changes in kern_shutdown 1.162.
Print a different message when there are no busy buffers after the
initial sync(), which is now the expected situation.
Print an additional message when syncing has completed successfully
in the unusual situation where the work of syncing was done by
boot().
Uppercase one message to make it consistent with all of the other
kernel shutdown messages.
Discussed with: bde (in a much earlier form, prior to 1.162)
Reviewed by: njl (in an earlier form)
work very infrequently, and often results in a compound panic which
confuses debugging; locking/SMP have made the layering violation (and
risks) of this more obvious over time.
Discussed with: green, bde, et al.
to not get a page fault if he has not defined a dump device.
Panic can often not do a dump as it can hang forever in some cases.
The original PR was for amd64 only. This is a generalised version of
that change.
PR: amd64/67712
Submitted by: wjw@withagen.nl <Willen Jan Withagen>
line as the announcement. Someone should probably update the "buffers
remaining" message since we now no longer should have any buffers remaining
at that point.
o Make debugging code conditional upon KDB instead of DDB.
o Call kdb_enter() instead of Debugger().
o Call kdb_backtrace() instead of db_print_backtrace() or backtrace().
kern_mutex.c:
o Replace checks for db_active with checks for kdb_active and make
them unconditional.
kern_shutdown.c:
o s/DDB_UNATTENDED/KDB_UNATTENDED/g
o s/DDB_TRACE/KDB_TRACE/g
o Save the TID of the thread doing the kernel dump so the debugger
knows which thread to select as the current when debugging the
kernel core file.
o Clear kdb_active instead of db_active and do so unconditionally.
o Remove backtrace() implementation.
kern_synch.c:
o Call kdb_reenter() instead of db_error().
than as one-off hacks in various other parts of the kernel:
- Add a function maybe_preempt() that is called from sched_add() to
determine if a thread about to be added to a run queue should be
preempted to directly. If it is not safe to preempt or if the new
thread does not have a high enough priority, then the function returns
false and sched_add() adds the thread to the run queue. If the thread
should be preempted to but the current thread is in a nested critical
section, then the flag TDF_OWEPREEMPT is set and the thread is added
to the run queue. Otherwise, mi_switch() is called immediately and the
thread is never added to the run queue since it is switch to directly.
When exiting an outermost critical section, if TDF_OWEPREEMPT is set,
then clear it and call mi_switch() to perform the deferred preemption.
- Remove explicit preemption from ithread_schedule() as calling
setrunqueue() now does all the correct work. This also removes the
do_switch argument from ithread_schedule().
- Do not use the manual preemption code in mtx_unlock if the architecture
supports native preemption.
- Don't call mi_switch() in a loop during shutdown to give ithreads a
chance to run if the architecture supports native preemption since
the ithreads will just preempt DELAY().
- Don't call mi_switch() from the page zeroing idle thread for
architectures that support native preemption as it is unnecessary.
- Native preemption is enabled on the same archs that supported ithread
preemption, namely alpha, i386, and amd64.
This change should largely be a NOP for the default case as committed
except that we will do fewer context switches in a few cases and will
avoid the run queues completely when preempting.
Approved by: scottl (with his re@ hat)
switch to. If a non-NULL thread pointer is passed in, then the CPU will
switch to that thread directly rather than calling choosethread() to pick
a thread to choose to.
- Make sched_switch() aware of idle threads and know to do
TD_SET_CAN_RUN() instead of sticking them on the run queue rather than
requiring all callers of mi_switch() to know to do this if they can be
called from an idlethread.
- Move constants for arguments to mi_switch() and thread_single() out of
the middle of the function prototypes and up above into their own
section.
The big lines are:
NODEV -> NULL
NOUDEV -> NODEV
udev_t -> dev_t
udev2dev() -> findcdev()
Various minor adjustments including handling of userland access to kernel
space struct cdev etc.
SW_INVOL. Assert that one of these is set in mi_switch() and propery
adjust the rusage statistics. This is to simplify the large number of
users of this interface which were previously all required to adjust the
proper counter prior to calling mi_switch(). This also facilitates more
switch and locking optimizations.
- Change all callers of mi_switch() to pass the appropriate paramter and
remove direct references to the process statistics.
prototypes of cpu_halt(), cpu_reset() and swi_vm() from md_var.h to
cpu.h. This affects db_command.c and kern_shutdown.c.
ia64: move all MD prototypes from cpu.h to md_var.h. This affects
madt.c, interrupt.c and mp_machdep.c. Remove is_physical_memory().
It's not used (vm_machdep.c).
alpha: the MD prototypes have been left in cpu.h with a comment
that they should be there. Moving them is left for later. It was
expected that the impact would be significant enough to be done in
a seperate commit.
powerpc: MD prototypes left in cpu.h. Comment added.
Suggested by: bde
Tested with: make universe (pc98 incomplete)
panics. Before revision 1.38, we used to just point panicstr at the
format string if panicstr was NULL, but since we now use a static
buffer for the formatted panic message, we have to be careful to
only write to it during the first panic.
Pointed out by: bde
void backtrace(void);
function which will print a backtrace if DDB is in the kernel and an
explanation if not.
This is useful for recording backtraces in non-fatal circumstances and
does not require pollution with DDB #includes in the files where it
is used.
It would of course be nice to have a non-DDB dependent version too,
but since the meat of a backtrace is MD it is probably not worth it.
permits MAC modules to augment system security decisions regarding
the reboot() system call, if MAC is compiled into the kernel.
Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories
as sparc64/sparc64/dump_machdep.c a while back).
Other than ia64 (which uses ELF), sparc64 uses a homegrown format for
the dumps (headers are required because the physical address and size of
the tsb must be noted, and because physical memory may be discontiguous);
ELF would not offer any advantages here.
Reviewed by: jake
the kernel. By default this is turned off since otherwise it could scroll
valuable panic messages off of the screen. This option can be turned on
by the DDB_TRACE kernel option as well as the debug.trace_on_panic sysctl.
Also, fix the DDB_UNATTENDED option to use its own header instead of
abusing opt_ddb.h. This way turning that one option on or off doesn't
force you to recompile all of ddb.
Requested by: many (1), bde (2*)
* - I know bde prefers !abusing option headers in general but can't
remember if he as brought up this specific case.
other references to that vnode as a trace vnode in other processes as well
as in any pending requests on the todo list. Thus, it is possible for a
ktrace request structure to have a NULL ktr_vp when it is destroyed in
ktr_freerequest(). We shouldn't call vrele() on the vnode in that case.
Reported by: bde
after a panic which is not an interrupt thread, or the thread which
caused the panic. Also, remove panicstr checks from msleep() and from
cv_wait() in order to allow threads to go to sleep and yeild the cpu
to the panicing thread, or to an interrupt thread which might
be doing the crashdump.
Reviewed by: jhb (and it was mostly his idea too)
The ability to schedule multiple threads per process
(one one cpu) by making ALL system calls optionally asynchronous.
to come: ia64 and power-pc patches, patches for gdb, test program (in tools)
Reviewed by: Almost everyone who counts
(at various times, peter, jhb, matt, alfred, mini, bernd,
and a cast of thousands)
NOTE: this is still Beta code, and contains lots of debugging stuff.
expect slight instability in signals..
